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Cover Page - USD ($)	12 Months Ended
Cover Page - USD ($)	Dec. 31, 2019	Feb. 21, 2020	Jun. 30, 2019
Cover page.
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	001-35416
Entity Registrant Name	U.S. Silica Holdings, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	26-3718801
Entity Address, Address Line One	24275 Katy Freeway, Suite 600
Entity Address, City or Town	Katy
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77494
City Area Code	281
Title of 12(b) Security	Common Stock, par value $0.01 per share
Local Phone Number	258-2170
Trading Symbol	SLCA
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Interactive Data Current	Yes
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 905,828,280
Entity Common Stock, Shares Outstanding		73,750,501
Documents Incorporated by Reference	Certain sections of the Proxy Statement for the 2020 Annual Meeting of Shareholders for U.S. Silica Holdings, Inc. (the “2020 Proxy Statement”) are incorporated by reference in Part III of this Annual Report on Form 10-K where indicated.
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Entity Central Index Key	0001524741
Current Fiscal Year End Date	--12-31

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current Assets:
Cash and cash equivalents	$ 185,740	$ 202,498
Accounts receivable, net	182,238	215,486
Inventories, net	124,432	162,087
Prepaid expenses and other current assets	16,155	17,966
Income tax deposits	475	2,200
Total current assets	509,040	600,237
Property, plant and mine development, net	1,517,587	1,826,303
Operating lease right-of-use assets	53,098
Goodwill	273,524	261,340
Intangible assets, net	183,815	194,626
Other assets	16,170	18,334
Total assets	2,553,234	2,900,840
Current Liabilities:
Accounts payable and accrued expenses	248,237	216,400
Current portion of operating lease liabilities	53,587
Current portion of long-term debt	18,463	13,327
Current portion of deferred revenue	15,111	31,612
Total current liabilities	335,398	261,339
Long-term debt, net	1,213,985	1,246,428
Deferred revenue	35,523	81,707
Liability for pension and other post-retirement benefits	58,453	57,194
Deferred income taxes, net	38,585	137,239
Operating lease liabilities	117,964
Other long-term obligations	36,746	64,629
Total liabilities	1,836,654	1,848,536
Commitments and Contingencies (Note Q)
Stockholders’ Equity:
Preferred stock, $0.01 par value, 10,000,000 shares authorized; zero issued and outstanding at December 31, 2019 and 2018	0	0
Common stock, $0.01 par value, 500,000,000 shares authorized; 82,601,926 issued and 73,601,950 outstanding at December 31, 2019; 81,811,977 issued and 73,148,853 outstanding at December 31, 2018	823	818
Additional paid-in capital	1,185,116	1,169,383
Retained (deficit) earnings	(279,956)	67,854
Treasury stock, at cost, 8,999,976 and 8,663,124 shares at December 31, 2019 and 2018, respectively	(180,912)	(178,215)
Accumulated other comprehensive loss	(19,854)	(15,020)
Total U.S. Silica Holdings, Inc. stockholders’ equity	705,217	1,044,820
Non-controlling interest	11,363	7,484
Total stockholders' equity	716,580	1,052,304
Total liabilities and stockholders’ equity	$ 2,553,234	$ 2,900,840

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock authorized (shares)	10,000,000	10,000,000
Preferred stock issued (shares)	0	0
Preferred stock outstanding (shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock authorized (shares)	500,000,000	500,000,000
Common stock issued (shares)	82,601,926	81,811,977
Common stock outstanding (shares)	73,601,950	73,148,853
Treasury stock, at cost (shares)	8,999,976	8,663,124

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Sales:
Total sales									$ 1,474,477	$ 1,577,298	$ 1,240,851
Cost of sales (excluding depreciation, depletion and amortization):
Total cost of sales (excluding depreciation, depletion and amortization)									1,133,293	1,163,129	866,820
Operating expenses:
Selling, general and administrative	$ 37,325	$ 40,208	$ 38,659	$ 34,656	$ 32,168	$ 37,980	$ 42,232	$ 34,591	150,848	146,971	107,056
Depreciation, depletion and amortization	42,819	47,126	44,899	44,600	46,527	37,150	36,563	28,592	179,444	148,832	97,233
Goodwill and other asset impairments	363,717	130	0	0	265,715	0	16,184	0	363,847	281,899	0
Total operating expenses	443,861	87,464	83,558	79,256	344,410	75,130	94,979	63,183	694,139	577,702	204,289
Operating (loss) income	(362,764)	(9,283)	17,136	1,956	(274,068)	25,706	39,609	45,220	(352,955)	(163,533)	169,742
Other (expense) income:
Interest expense	(22,996)	(24,733)	(23,765)	(23,978)	(21,281)	(21,999)	(20,214)	(7,070)	(95,472)	(70,564)	(31,342)
Other income (expense), net, including interest income	443	3,280	15,074	722	1,336	1,062	1,081	665	19,519	4,144	(1,874)
Total other expense	(22,553)	(21,453)	(8,691)	(23,256)	(19,945)	(20,937)	(19,133)	(6,405)	(75,953)	(66,420)	(33,216)
(Loss) income before income taxes	(385,317)	(30,736)	8,445	(21,300)	(294,013)	4,769	20,476	38,815	(428,908)	(229,953)	136,526
Income tax benefit	91,892	7,671	(2,384)	1,972	37,938	1,547	(2,832)	(7,521)	99,151	29,132	8,680
Net (loss) income	(293,425)	(23,065)	6,061	(19,328)	(256,075)	6,316	17,644	31,294	(329,757)	(200,821)	145,206
Less: Net loss attributable to non-controlling interest	(554)	(28)	(89)	(4)	(13)	0	0	0	(675)	(13)	0
Net (loss) income attributable to U.S. Silica Holdings, Inc.	$ (292,871)	$ (23,037)	$ 6,150	$ (19,324)	$ (256,062)	$ 6,316	$ 17,644	$ 31,294	$ (329,082)	$ (200,808)	$ 145,206
(Loss) earnings per share attributable to U.S. Silica Holdings, Inc.:
Basic (in dollars per share)	$ (4.00)	$ (0.31)	$ 0.08	$ (0.26)	$ (3.44)	$ 0.08	$ 0.23	$ 0.39	$ (4.49)	$ (2.63)	$ 1.79
Diluted (in dollars per share)	$ (4.00)	$ (0.31)	$ 0.08	$ (0.26)	$ (3.44)	$ 0.08	$ 0.22	$ 0.39	$ (4.49)	$ (2.63)	$ 1.77
Weighted average shares outstanding:
Basic (shares)	73,343	73,328	73,301	73,040	74,485	77,365	77,784	79,496	73,253	76,453	81,051
Diluted (shares)									73,253	76,453	81,960
Dividends declared per share (in dollars per share)	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.25	$ 0.25	$ 0.25
Product
Sales:
Total sales	$ 280,594	$ 287,977	$ 303,041	$ 296,860	$ 293,419	$ 348,635	$ 345,957	$ 294,788	$ 1,168,472	$ 1,282,799	$ 1,010,394
Cost of sales (excluding depreciation, depletion and amortization):
Total cost of sales (excluding depreciation, depletion and amortization)	212,905	226,797	225,473	234,916	241,624	270,370	236,236	207,239	900,091	955,469	714,521
Service
Sales:
Total sales	58,465	73,837	91,813	81,890	63,961	74,537	81,476	74,525	306,005	294,499	230,457
Cost of sales (excluding depreciation, depletion and amortization):
Total cost of sales (excluding depreciation, depletion and amortization)	$ 45,057	$ 56,836	$ 68,687	$ 62,622	$ 45,414	$ 51,966	$ 56,609	$ 53,671	$ 233,202	$ 207,660	$ 152,299

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (293,425)	$ (23,065)	$ 6,061	$ (19,328)	$ (256,075)	$ 6,316	$ 17,644	$ 31,294	$ (329,757)	$ (200,821)	$ 145,206
Other comprehensive (loss) income:
Unrealized loss on derivatives (net of tax of $(456), $(470), and $(27) for 2019, 2018, and 2017, respectively)									(1,432)	(1,545)	(44)
Foreign currency translation adjustment (net of tax of $(60), $(196), and $2 for 2019, 2018 and 2017, respectively)									(188)	(614)	(6)
Pension and other post-retirement benefits liability adjustment (net of tax of $(1,024), $339, and $1,205 for 2019, 2018 and 2017, respectively)									(3,214)	1,065	2,000
Comprehensive (loss) income									(334,591)	(201,915)	147,156
Less: Comprehensive loss attributable to non-controlling interest									(675)	(13)	0
Comprehensive (loss) income attributable to U.S. Silica Holdings, Inc.									$ (333,916)	$ (201,902)	$ 147,156

- Definition

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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+ Details

Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Tax expense (benefit) on unrealized gain (loss) on derivatives	$ (456)	$ (470)	$ (27)
Tax expense (benefit) on foreign currency translation adjustment	(60)	(196)	2
Tax (expense) benefit on pension and other post-retirement benefits liability adjustment	$ (1,024)	$ 339	$ 1,205

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Total U.S. Silica Holdings Inc., Stockholders’ Equity	Common Stock	Treasury Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Non-controlling Interest
Beginning Balance at Dec. 31, 2016	$ 1,273,290	$ 1,273,290	$ 811	$ (3,869)	$ 1,129,051	$ 163,173	$ (15,876)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	145,206	145,206				145,206
Unrealized loss on derivatives	(44)	(44)					(44)
Foreign currency translation adjustment	(6)	(6)					(6)
Pension and post-retirement liability	2,000	2,000					2,000
Cash dividend declared ($0.25 per share for 2019, 2018 and 2017, respectively)	(20,387)	(20,387)				(20,387)
Common stock-based compensation plans activity:
Equity-based compensation	25,050	25,050			25,050
Proceeds from options exercised	798	798		1,190	(392)
Issuance of restricted stock	0			1,859	(1,859)
Shares withheld for tax payments related to vested restricted stock and stock units	(4,379)	(4,379)	1	386	(4,766)
Repurchase of common stock	(25,022)	(25,022)		(25,022)
Ending Balance at Dec. 31, 2017	1,396,506	1,396,506	812	(25,456)	1,147,084	287,992	(13,926)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(200,821)	(200,808)				(200,808)		(13)
Unrealized loss on derivatives	(1,545)	(1,545)					(1,545)
Foreign currency translation adjustment	(614)	(614)					(614)
Pension and post-retirement liability	1,065	1,065					1,065
Cash dividend declared ($0.25 per share for 2019, 2018 and 2017, respectively)	(19,330)	(19,330)				(19,330)
Contributions from non-controlling interest	7,497							7,497
Common stock-based compensation plans activity:
Equity-based compensation	22,337	22,337			22,337
Proceeds from options exercised	61	61		93	(32)
Shares withheld for tax payments related to vested restricted stock and stock units	(4,383)	(4,383)	6	(4,383)	(6)
Repurchase of common stock	(148,469)	(148,469)		(148,469)
Ending Balance at Dec. 31, 2018	1,052,304	1,044,820	818	(178,215)	1,169,383	67,854	(15,020)	7,484
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(329,757)	(329,082)				(329,082)		(675)
Unrealized loss on derivatives	(1,432)	(1,432)					(1,432)
Foreign currency translation adjustment	(188)	(188)					(188)
Pension and post-retirement liability	(3,214)	(3,214)					(3,214)
Cash dividend declared ($0.25 per share for 2019, 2018 and 2017, respectively)	(18,728)	(18,728)				(18,728)
Contributions from non-controlling interest	4,554							4,554
Common stock-based compensation plans activity:
Equity-based compensation	15,906	15,906			15,906
Proceeds from options exercised	128	128		296	(168)
Shares withheld for tax payments related to vested restricted stock and stock units	(2,993)	(2,993)	5	(2,993)	(5)
Ending Balance at Dec. 31, 2019	$ 716,580	$ 705,217	$ 823	$ (180,912)	$ 1,185,116	$ (279,956)	$ (19,854)	$ 11,363

Consolidated Statements of Stockholders' Equity (Parenthetical) - $ / shares	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Stockholders' Equity [Abstract]
Cash dividend declared (in dollars per share)	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.25	$ 0.25	$ 0.25

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating activities:
Net (loss) income	$ (329,757)	$ (200,821)	$ 145,206
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation, depletion and amortization	179,444	148,832	97,233
Goodwill and other asset impairments	363,847	281,899	0
Debt issuance amortization	5,597	4,044	1,382
Original issue discount amortization	1,053	832	372
Gain on valuation change of royalty note payable	(16,854)	0	0
Inventory step-up adjustments	22,373	20,107	3,812
Deferred income taxes	(101,682)	(31,070)	(20,601)
Deferred revenue	(74,910)	(36,720)	28,438
(Loss) gain on disposal of property, plant and equipment	1,573	(5,170)	415
Equity-based compensation	15,906	22,337	25,050
Bad debt provision, net of recoveries	3,466	315	1,529
Other	(12,042)	(13,536)	13,929
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable	33,837	56,815	(110,920)
Inventories	11,182	(7,022)	(8,637)
Prepaid expenses and other current assets	8,547	(2,678)	8,787
Income taxes	1,725	(3,764)	1,469
Accounts payable and accrued expenses	21,024	26,907	43,654
Short-term and long-term obligations-vendor incentives	4,021	52,806	0
Liability for pension and other post-retirement benefits	2,734	4,608	(705)
Other noncurrent assets and liabilities	2,962	(8,015)	(8,400)
Net cash provided by operating activities	144,046	310,706	222,013
Investing activities:
Capital expenditures	(118,357)	(339,815)	(368,479)
Capitalized intellectual property costs	(3,932)	(10,046)	(3,586)
Acquisition of businesses, net of cash acquired	0	(743,249)	(119,801)
Proceeds from sale of property, plant and equipment	1,896	26,231	337
Net cash used in investing activities	(120,393)	(1,066,879)	(491,529)
Financing activities:
Dividends paid	(18,592)	(19,912)	(20,377)
Repurchase of common stock	0	(148,469)	(25,022)
Proceeds from options exercised	128	61	798
Tax payments related to shares withheld for vested restricted stock and stock units	(2,993)	(4,383)	(4,379)
Proceeds from long-term debt	0	1,280,000	0
Payments on long-term debt	(23,449)	(501,425)	(7,211)
Financing fees paid	0	(38,701)	0
Contributions from non-controlling interest	4,554	7,497	0
Principal payments on capital lease obligations	(59)	(564)	(951)
Net cash (used in) provided by financing activities	(40,411)	574,104	(57,142)
Net decrease in cash and cash equivalents	(16,758)	(182,069)	(326,658)
Cash and cash equivalents, beginning of period	202,498	384,567	711,225
Cash and cash equivalents, end of period	185,740	202,498	384,567
Cash paid (received) during the period for:
Interest	87,286	66,769	24,490
Taxes, net of refunds	(14,741)	5,373	8,958
Related party purchases	0	2,958	4,942
Non-cash Items:
Equipment received	0	0	18,185
Accrued capital expenditures	27,646	36,008	16,534
Capital lease assumed by third-party	0	119	0
Asset retirement obligation assumed by third-party	$ 0	$ 2,116	$ 0

Organization	12 Months Ended
Organization	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
ORGANIZATION	NOTE A—ORGANIZATION U.S. Silica Holdings, Inc. (“Holdings,” and together with its subsidiaries “we,” “us” or the “Company”) is a performance materials company and a leading producer of commercial silica used in the oil and gas industry and in a wide range of industrial applications. In addition, through our acquisition of EP Minerals, LLC ("EPM") and its affiliated companies, we are an industry leader in the production of products derived from diatomaceous earth, perlite, engineered clays, and non-activated clays. During our 120-year history, we have developed core competencies in mining, processing, logistics and materials science that enable us to produce and cost-effectively deliver products to customers across our end markets. Our operations are organized into two reportable segments based on end markets served: (1) Oil & Gas Proppants and (2) Industrial & Specialty Products. See Note W - Segment Reporting for more information on our reportable segments. On May 1, 2018, we completed the acquisition of all of the outstanding capital stock of EP Acquisition Parent, Inc., a Delaware corporation (“EPAP”), and the ultimate parent of EPM. Contemporaneous with the merger, EPAP was renamed EP Minerals Holdings, Inc. ("EPMH"). The consideration paid consisted of $743.2 million of cash, net of cash acquired of $19.1 million, including $0.5 million of post-closing adjustments. EPM is a global producer of engineered materials derived from industrial minerals, including diatomaceous earth, clay (calcium bentonite) and perlite. EPM's industrial minerals are used as filter aids, absorbents and functional additives for a variety of industries including food and beverage, biofuels, recreational water, oil and gas, farm and home, landscape, sports turf, paint, plastics, and insecticides. The acquisition of EPM increased our industrial materials product offering in our Industrial & Specialty Products segment. On August 16, 2017, we completed the acquisition of Mississippi Sand, LLC ("MS Sand"). MS Sand is a frac sand mining and logistics company based in St. Louis, Missouri. On April 1, 2017, we completed the acquisition of White Armor, a product line of cool roof granules used in industrial roofing applications. See Note E - Business Combinations for more information.

Summary of Significant Accounting Policies	12 Months Ended
Summary of Significant Accounting Policies	Dec. 31, 2019
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	NOTE B—SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation and Consolidation The accompanying Consolidated Financial Statements have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”). In the opinion of management, all adjustments necessary for a fair presentation of the Consolidated Financial Statements have been included. Such adjustments are of a normal, recurring nature. Throughout this report we refer to (i) our Consolidated Balance Sheets as our “Balance Sheets,” (ii) our Consolidated Statements of Operations as our “Income Statements,” and (iii) our Consolidated Statements of Cash Flows as our “Cash Flows.” Consolidation The Consolidated Financial Statements include the accounts of Holdings and its direct and indirect wholly-owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. We follow FASB Accounting Standards Codification (“ASC”) guidance for identification and reporting of entities over which control is achieved through means other than voting rights. The guidance defines such entities as Variable Interest Entities (“VIEs”). We consolidate VIEs when we have variable interests and are the primary beneficiary. We continually evaluate our involvement with VIEs to determine when these criteria are met. During the third quarter of 2018 we finalized a shareholders' agreement with unrelated parties to form a limited liability company with the purpose of constructing and operating a water pipeline to transport and sell water. In connection with the shareholders’ agreement, we acquired a 50% equity ownership for $3.2 million, with a maximum initial capital contribution of $7.0 million, and a water rights intangible asset for $0.7 million. Based on our evaluation, we determined that this limited liability company is a VIE of which we are the primary beneficiary and therefore we are required to consolidate it. As of December 31, 2019, the VIE had total assets of $18.3 million and total liabilities of $0.4 million. We made capital contributions in the amounts of $0.4 million and $7.0 million during the years ended December 31, 2019 and December 31, 2018, respectively. Reclassifications Certain reclassifications of prior period presentations have been made to conform to the current period presentation. Use of Estimates and Assumptions The preparation of Consolidated Financial Statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the related disclosure of contingent assets and liabilities at the date of the Consolidated Financial Statements and the reported amounts of revenues and expenses during the reporting period. The more significant areas requiring the use of management estimates and assumptions relate to the purchase price allocation for businesses acquired; mineral reserves that are the basis for future cash flow estimates utilized in impairment calculations and units-of-production amortization calculations; environmental, reclamation and closure obligations; estimates of recoverable minerals; estimates of allowance for doubtful accounts; estimates of fair value for certain reporting units and asset impairments (including impairments of goodwill, intangible assets and other long-lived assets); write-downs of inventory to net realizable value; equity-based compensation expense; post-employment, post-retirement and other employee benefit liabilities; valuation allowances for deferred tax assets; contingent considerations; reserves for contingencies and litigation and the fair value and accounting treatment of financial instruments, including derivative instruments. We base our estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances. Accordingly, actual results may differ significantly from these estimates under different assumptions or conditions. Cash and Cash Equivalents Cash and cash equivalents consist of all highly liquid investments with a maturity of three months or less when purchased. Because of the short maturity of these investments, the carrying amounts approximate their fair value. Cash and cash equivalents are invested primarily in money market securities held by financial institutions with high credit ratings. Accounts at each institution are insured by the Federal Deposit Insurance Corporation. Cash balances at times may exceed federally-insured limits. We have not experienced any losses in such accounts and believe we are not exposed to any significant credit risk on cash. Accounts Receivable The majority of our accounts receivable are due from companies in the oil and natural gas drilling, building and construction products, filler and extenders, filtration, glass, absorbents, foundry, sports and recreation, and other major industries. Credit is extended based on evaluation of a customer’s financial condition and, generally, collateral is not required. Accounts receivable are stated at amounts due from customers net of an allowance for doubtful accounts. Accounts outstanding longer than the payment terms are considered past due. We determine our allowance by considering a number of factors, including the length of time trade accounts receivable are past due, our previous loss history, the customer’s current ability to pay its obligation to us, and the condition of the general economy and the industry as a whole. Ongoing credit evaluations are performed. We write-off accounts receivable when they are deemed uncollectible, and payments subsequently received on such receivables are credited to the allowance for doubtful accounts. See Note F - Accounts Receivable and Note U - Revenue. Inventories Inventories include raw stockpiles, in-process product and finished product available for shipment, as well as spare parts and supplies for routine facility maintenance. We value inventory at the lower of cost and net realizable value. Cost is determined using the first-in, first-out and average cost methods. Our inventoriable costs include production costs and transportation and additional service costs as applicable. See Note G - Inventories. Property, Plant and Mine Development Plant and equipment Plant and equipment is recorded at cost and depreciated over their estimated useful lives. Interest incurred during construction of facilities is capitalized and depreciated over the life of the asset. Costs for normal repairs and maintenance that do not extend economic life or improve service potential are expensed as incurred. Costs of improvements that extend economic life or improve service potential are capitalized and depreciated over the estimated remaining useful life. Depreciation is recorded using the straight-line method over the assets’ estimated useful lives as follows: buildings (15 years); land improvements (10 years); machinery and equipment, including computer equipment and software (3-10 years); furniture and fixtures (8 years). Leasehold improvements are depreciated over the shorter of the asset life or lease term. Construction-in-progress is primarily comprised of machinery and equipment which have not yet been placed in service. Mining property and development Mining property and development includes mineral deposits and mine exploration and development. Mineral deposits are initially recognized at cost, which approximates the estimated fair value on the date of purchase. Mine exploration and development costs include engineering and mineral studies, drilling and other related costs to delineate an ore body, and the removal of overburden to initially expose an ore body for production. Costs incurred before mineralization are classified as proven and probable reserves are expensed and classified as exploration or advanced projects, research and development expense. Capitalization of mine development project costs, that meet the definition of an asset, begins once mineralization is classified as proven and probable reserves. The cost of removing overburden and waste materials to access the ore body at an open pit mine prior to the production phase are referred to as “pre-stripping costs.” Pre-stripping costs are capitalized during the development of an open pit mine. The production phase of an open pit mine commences when saleable minerals, beyond a de minimis amount, are produced. Stripping costs incurred during the production phase of a mine are variable production costs that are included as a component of inventory to be recognized in costs applicable to sales in the same period as the revenue from the sale of inventory. Depletion and amortization of mineral deposits and mine development costs are recorded as the minerals are extracted, based on units of production and engineering estimates of mineable reserves. The impact of revisions to reserve estimates is recognized on a prospective basis. See Note H - Property, Plant and Mine Development. Mine reclamation costs and asset retirement obligations We recognize the fair value of any liability for conditional asset retirement obligations, including environmental remediation liabilities when incurred, which is generally upon acquisition, construction or development and/or through the normal operation of the asset, if sufficient information exists to reasonably estimate the fair value of the liability. These obligations generally include the estimated net future costs of dismantling, restoring and reclaiming operating mines and related mine sites, in accordance with federal, state, local regulatory and land lease agreement requirements. The liability is accreted over time through periodic charges to earnings. In addition, the asset retirement cost is capitalized as part of the asset’s carrying value and amortized over the life of the related asset. Reclamation costs are periodically adjusted to reflect changes in the estimated present value resulting from the passage of time and revisions to the estimates of either the timing or amount of the reclamation and abandonment costs. The reclamation obligation is based on when spending for an existing environmental disturbance will occur. If the asset retirement obligation is settled for other than the carrying amount of the liability, a gain or loss is recognized on settlement. We review, on an annual basis, unless otherwise deemed necessary, the reclamation obligation at each mine site in accordance with ASC guidance for accounting for reclamation obligations. See Note M - Asset Retirement Obligations. Impairment or Disposal of Property, Plant and Mine Development We periodically evaluate whether current events or circumstances indicate that the carrying value of our property, plant and equipment assets may not be recoverable. If circumstances indicate that the carrying value may not be recoverable, we estimate future undiscounted net cash flows using estimates of proven and probable sand reserves, estimated future sales prices (considering historical and current prices, price trends and related factors) and operating costs and anticipated capital expenditures. If the undiscounted cash flows are less than the carrying value of the assets, we recognize an impairment loss equal to the amount by which the carrying value exceeds the fair value of the assets. The recoverability of the carrying value of our mineral properties is dependent upon the successful development, start-up and commercial production of our mineral deposit and the related processing facilities. Our evaluation of mineral properties for potential impairment primarily includes assessing the existence or availability of required permits and evaluating changes in our mineral reserves, or the underlying estimates and assumptions, including estimated production costs. Assessing the economic feasibility requires certain estimates, including the prices of products to be produced and processing recovery rates, as well as operating and capital costs. Gains on the sale of property, plant and mine development are included in income when the assets are disposed of provided there is more than reasonable certainty of the collectability of the sales price and any future activities required to be performed by us relating to the disposal of the assets are complete or insignificant. Upon retirement or disposal of assets, all costs and related accumulated depreciation or amortization are written-off. Goodwill and Other Intangible Assets and Related Impairment Our intangible assets consist of goodwill, which is not being amortized, indefinite-lived intangibles, which consist of certain trade names that are not subject to amortization, intellectual property and customer relationships. Intellectual property mainly consists of patents and technology, and it is amortized on a straight-line basis over an average useful life of 15 years. Customer relationships are amortized on a straight-line basis over their useful life of 20, 15 or 13 years. Goodwill represents the excess of the purchase price of business combinations over the fair value of net assets acquired. Goodwill and trade names are reviewed for impairment annually as of October 31, or more frequently when indicators of impairment exist. An impairment exists if the fair value of a reporting unit to which goodwill has been allocated, or the fair value of indefinite-lived intangible assets, is less than their respective carrying values. Prior to conducting a formal impairment test, we have an option to assess qualitative factors to determine whether the existence of events or circumstances leads to a determination that is more likely than not (more than 50%) that the fair value of a reporting unit is less than its carrying amount. Such qualitative factors may include the following: macroeconomic conditions; industry and market considerations; cost factors; overall financial performance; and other relevant entity-specific events. If the qualitative assessment determines that an impairment is more likely than not, or if we choose to bypass the qualitative assessment, we perform a quantitative assessment by comparing the fair value of a reporting unit with its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. See Note I - Goodwill and Intangible Assets. Leases We lease railroad cars, office space, mining property, mining/processing equipment and transportation and other equipment. Operating leases are included in operating lease right-of-use (“ROU”) assets, current portion of operating lease liabilities, and operating lease liabilities in our consolidated balance sheets. Finance leases are included in property, plant and mine development, current portion of long-term debt, and long-term debt in our consolidated balance sheets. Leases with an initial term of 12 months or less are not recorded on the balance sheet. ROU assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. ROU assets and liabilities are recognized at the commencement date of the lease based on the present value of lease payments over the lease term. As most of our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. The ROU assets also include any lease payments made at or before the commencement date of the lease and excludes lease incentives. Our lease terms may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Lease expense for lease payments is recognized on a straight-line basis over the lease term. We have lease agreements with lease and non-lease components, the latter of which are generally accounted for separately. See Note S - Leases. We periodically evaluate whether current events or circumstances indicate that the carrying value of our right-of-use assets exceeds fair value. If circumstances indicate an impairment exists, we estimate fair value primarily utilizing internally developed cash flow models and quoted market prices, discounted at an appropriate weighted average cost of capital. If the undiscounted cash flows are less than the carrying value of the assets, we recognize an impairment loss equal to the amount by which the carrying value exceeds the fair value of the assets. Revenue Recognition Products We derive our product sales by mining and processing minerals that our customers purchase for various uses. Our product sales are primarily a function of the price per ton and the number of tons sold. We primarily sell our products through individual purchase orders executed under short-term price agreements or at prevailing market rates. The amount invoiced reflects product, transportation and / or additional handling services as applicable, such as storage, transloading the product from railcars to trucks and last mile logistics to the customer site. We invoice most of our product customers on a per shipment basis, although for some larger customers, we consolidate invoices weekly or monthly. Standard collection terms are net 30 days, although extended terms are offered in competitive situations. We recognize revenue for products and materials at a point in time following the transfer of control of such items to the customer, which typically occurs upon shipment or delivery depending on the terms of the underlying contracts. We account for shipping and handling activities related to product and material sales contracts with customers as costs to fulfill our promise to transfer the associated products pursuant to the accounting policy election allowed under ASC 606-10-25-18b. Accordingly, we record amounts billed for shipping and handling costs as a component of net sales and accrue and classify related costs as a component of cost of sales at the time revenue is recognized. For a limited number of customers, we sell under long-term, minimum purchase supply agreements. These agreements define, among other commitments, the volume of product that our customers must purchase, the volume of product that we must provide and the price that we will charge and that our customers will pay for each product. Prices under these agreements are generally fixed and subject to certain contractual adjustments. Sometimes these agreements may undergo negotiations regarding pricing and volume requirements, which may often occur in volatile market conditions. While these negotiations continue, we may deliver sand at prices or at volumes below the requirements in our existing supply agreements. An executed order specifying the type and quantity of product to be delivered, in combination with the noted agreements, comprise our contracts in these arrangements. Service We derive our service revenues primarily through the provision of transportation, equipment rental, and contract labor services to companies in the oil and gas industry. Transportation services typically consist of transporting customer proppant from storage facilities to proximal well-sites and are contracted through work orders executed under established pricing agreements. The amount invoiced reflects the transportation services rendered. Equipment rental services provide customers with use of either dedicated or nonspecific wellhead proppant delivery equipment solutions for contractual periods defined either through formal lease agreements or executed work orders under established pricing agreements. The amounts invoiced reflect the length of time the equipment set was utilized in the billing period. Contract labor services provide customers with proppant delivery equipment operators through work orders executed under established pricing agreements. The amounts invoiced reflect the amount of time our labor services were utilized in the billing period. We typically invoice our customers on a weekly or monthly basis; however, some customers receive invoices upon well-site operation completion. Standard collection terms are net 30 days, although extended terms are offered in competitive situations. We typically recognize revenue for specific, dedicated equipment set rental arrangements under ASC 842, Leases. For the remaining components of service revenue, we have applied the practical expedient allowed under ASC 606-10-55-18 to recognize transportation revenues in proportion to the amount we have the right to invoice. Contracts with Multiple Performance Obligations From time to time, we may enter into contracts that contain multiple performance obligations, such as work orders containing a combination of product, transportation, equipment rentals, and contract labor services. For these arrangements, we allocate the transaction price to each performance obligation identified in the contract based on relative standalone selling prices, or estimates of such prices, and recognize the related revenue as control of each individual product or service is transferred to the customer, in satisfaction of the corresponding performance obligations. We typically invoice our customers on a weekly or monthly basis; however, some customers receive invoices upon well-site operation completion. Standard collection terms are net 30 days, although extended terms are offered in competitive situations. Taxes Collected from Customers and Remitted to Governmental Authorities. We exclude from our measurement of transaction prices all taxes assessed by governmental authorities that are both (i) imposed on and concurrent with a specific revenue-producing transaction and (ii) collected from customers. Accordingly, such tax amounts are not included as a component of net sales or cost of sales. See Note U - Revenue. Deferred Revenues For a limited number of customers, we enter into supply agreements which give customers the right to make advanced payments toward the purchase of certain products at specified volumes over an average initial period of one to fifteen years. These payments represent consideration that is unconditional for which we have yet to transfer the related product. These payments are recorded as contract liabilities referred to as “deferred revenues” upon receipt and recognized as revenue upon delivery of the related product. Unbilled Receivables Revenues recognized in advance of invoice issuance create assets referred to as “unbilled receivables.” Any portion of our unbilled receivables for which our right to consideration is conditional on a factor other than the passage of time is considered a contract asset. These assets are presented on a combined basis with accounts receivable and are converted to accounts receivable once billed. Debt Issuance Costs The Company defers costs directly associated with acquiring third-party financing, primarily loan origination costs and related professional expenses. Debt issuance costs are deferred and amortized using the effective interest rate method over the term of our senior secured Term Loan facility and the straight-line method for our Revolver facility. Debt issuance costs related to long-term debt are reflected as a direct deduction from the carrying amount of the debt. Amortization included in interest expense was $5.6 million for the year ended December 31, 2019, and $4.0 million and $1.4 million for the years ended December 31, 2018 and 2017. See Note K - Debt. Employee Benefit Plans We provide a range of benefits to our employees and retired employees, including pensions and post-retirement healthcare and life insurance benefits. We record annual amounts relating to these plans based on calculations specified by generally accepted accounting principles, which include various actuarial assumptions, including discount rates, assumed rates of returns, compensation increases, turnover rates, mortality table, and healthcare cost trend rates. We review the actuarial assumptions on an annual basis and make modifications to the assumptions based on current rates and trends when it is deemed appropriate to do so. As required by U.S. generally accepted accounting principles, the effect of the modifications is generally recorded or amortized over future periods. We believe that the assumptions utilized in recording our obligations under the plans are reasonable based on advice from our actuaries and information as to assumptions used by other employers. See Note R - Pension and Post-Retirement Benefits. Environmental Costs Environmental costs, other than qualifying capital expenditures, are accrued at the time the exposure becomes known and costs can be reasonably estimated. Costs are accrued based upon management’s estimates of all direct costs, after taking into account expected reimbursement by third parties (primarily the sellers of acquired businesses) and are reviewed by outside consultants. Environmental costs are charged to expense unless a settlement with an indemnifying party has been reached. Self-Insurance We are self-insured for various levels of employee health insurance coverage, workers’ compensation and third-party product liability claims alleging occupational disease. We purchase insurance coverage for claim amounts which exceed our self-insured retentions. Depending on the type of insurance, these self-insured retentions range from $0.1 million to $0.5 million per occurrence. Our insurance reserves are accrued based on estimates of the ultimate cost of claims expected to occur during the covered period. Our insurance reserves are accrued based on estimates of the ultimate cost of claims expected to occur during the covered period. These estimates are prepared with the assistance of outside actuaries and consultants. Our actuaries periodically review the volume and amount of claims activity, and based upon their findings, we adjust our insurance reserves accordingly. The ultimate cost of claims for a covered period may differ from our original estimates. The current portion of our self-insurance reserves is included in accrued liabilities and the non-current portion is included in other long-term obligations in our Balance Sheets. As of December 31, 2019 and 2018, our self-insurance reserves totaled $6.6 million and $5.4 million, respectively, of which $4.1 million and $2.6 million, respectively, was classified as current. Research and Development Costs We may incur immaterial internal research and development (“R&D”) expenditures, and research and development conducted for others, all of which are expensed as incurred, and included in selling, general and administrative expense. R&D costs may include, but are not limited to, research and administrative salaries, contractor fees, building costs, utilities, administrative expenses, and allocations of corporate costs. Advertising Costs We recognize advertising expense when incurred as selling, general and administrative expense. Advertising costs have not been a significant component of expense for the years ended December 31, 2019, 2018, or 2017. Equity-based Compensation We grant stock options, restricted stock, restricted stock units and performance share units to certain of our employees and directors under the Amended and Restated U.S. Silica Holdings, Inc. 2011 Incentive Compensation Plan. We recognize the cost of employee services rendered in exchange for awards of equity instruments. Vesting of restricted stock and restricted stock units is based on the individual continuing to render service over a pre-defined vesting schedule, generally three years. Cash dividend equivalents are accrued and paid to the holders of time-based restricted stock units and restricted stock. The fair value of the restricted stock awards is equal to the market price of our stock at date of grant. The restricted award-related compensation expense is recognized, on a straight-line basis, over the vesting period. We grant performance share units to certain employees in which the number of shares of common stock ultimately received is determined based on achievement of certain performance thresholds over a specified performance period (generally three years) in accordance with the stock award agreement. Cash dividend equivalents are not accrued or paid on performance share units. We recognize expense based on the estimated vesting of our performance share units granted and the grant date market price. The estimated vesting of the performance share units is principally based on the probability of achieving certain financial performance levels during the vesting periods. In the period it becomes probable that the minimum performance criteria specified in the award agreement will be achieved, we recognize expense for the proportionate share of the total fair value of the award related to the vesting period that has already lapsed. The remaining fair value of the award is expensed on a straight-line basis over the remaining vesting period. We grant certain employees performance share units, the vesting of which is based on the Company’s total shareholder return (“TSR”) ranking among a peer group over a three-year period. The number of units that will vest will depend on the percentage ranking of the Company's TSR compared to the TSRs for each of the companies in the peer group over the performance period. For these awards subject to market conditions, a binomial-lattice model (i.e., Monte Carlo simulation model) is used to fair value these awards at grant date. The related compensation expense is recognized, on a straight-line basis, over the vesting period. We grant stock options to certain employees and directors. Stock options vest on a vesting schedule and the related compensation expense is recognized over the vesting period, usually over 3 or 4 years. In calculating the compensation expense for stock options granted, we estimate the fair value of each grant using the Black-Scholes option-pricing model. The fair value of stock options granted is based on the exercise price of the option and certain assumptions, which are evaluated and revised, as necessary, to reflect market conditions and experience. We account for forfeitures as they occur. Our expected term is the period of time over which the options are expected to remain outstanding. An increase in the expected term will increase compensation expense. The computation of the expected term is based on the simplified method, under which the expected term is presumed to be the mid-point between the average vesting date and the end of the contractual term. The assumptions for expected volatility are based on historical experience for the same periods as our expected lives. Risk-free interest rates are set using grant-date U.S. Treasury yield curves for the same periods as our expected lives. The expected dividend yield is based on our future dividend expectations for the same periods as our expected lives. See Note P - Equity-based Compensation. Income Taxes Deferred taxes are provided on the liability method whereby deferred tax assets are recognized for deductible temporary differences and operating loss and tax credit carry forwards and deferred tax liabilities are recognized for taxable temporary differences. This approach requires recognition of deferred tax liabilities and assets for the expected future tax consequences of events that have been included in the financial statements or tax returns. Under this method, deferred tax liabilities and assets are determined based upon the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the expenses are expected to reverse. Valuation allowances are provided if, based on the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. We recognize a tax benefit associated with an uncertain tax position when, in management’s judgment, it is more likely than not that the position will be sustained upon examination by a taxing authority. For a tax position that meets the more-likely-than-not recognition threshold, we initially and subsequently measure the tax benefit as the largest amount that we judge to have a greater than 50% likelihood of being realized upon ultimate settlement with a taxing authority. The liability associated with unrecognized tax benefits is adjusted periodically due to changing circumstances, such as the progress of tax audits, case law developments and new or emerging legislation. Such adjustments are recognized entirely in the period in which they are identified. The effective tax rate includes the net impact of changes in the liability for unrecognized tax benefits and subsequent adjustments as considered appropriate by management. The largest permanent item in computing both our effective tax rate and taxable income is the deduction allowed for statutory depletion. The deduction for statutory depletion does not necessarily change proportionately to changes in income before income taxes. See Note T - Income Taxes. Financial Instruments We currently use interest rate hedge agreements to manage interest costs and the risk associated with changing interest rates. Amounts to be paid or received under these hedge agreements are accrued as interest rates change and are recognized over the life of the hedge agreements as an adjustment to interest expense. Our policy is to not hold or issue derivative financial instruments for trading or speculative purposes. When entered into, these financial instruments are designated as hedges of underlying exposures, associated with our long-term debt, and are monitored to determine if they remain effective hedges. Gains and losses on derivatives designated as cash flow hedges are recorded in other comprehensive income (loss), net of tax, and reclassified to earnings in a manner that matches the timing of the earnings impact of the hedged transactions. The ineffective portion of all hedges, if any, is recognized currently in income. See Note O - Derivative Instruments. Foreign Currency Translation For our operations in countries where the functional currency is other than the U.S. dollar, balance sheet amounts are translated using the exchange rate in effect at the balance sheet date. Income statement amounts are translated monthly using the average exchange rate for the respective month. The gains and losses resulting from the changes in exchange rates from year-to-year are recorded as a component of accumulated other comprehensive income or loss as currency translation adjustments, net of tax. Any gains or losses on transactions in currencies other than the functional currency are included in other income (expense), net, including interest income. For the years ended December 31, 2019 and 2018, we recorded net realized foreign currency transaction losses of $0.2 million and $0.6 million, respectively. We had no significant foreign operations during the year ended December 31, 2017. Comprehensive Income (loss) In addition to net income (loss), comprehensive income (loss) includes all changes in equity during a period, such as adjustments to minimum pension liabilities and the effective portion of changes in fair value of derivative instruments that qualify as cash flow hedges. Business Combinations The Company accounts for business combinations using the acquisition method of accounting. Under this method, acquired assets, including separately identifiable intangible assets and any assumed liabilities, are recorded at their acquisition date estimated fair value. The excess of purchase price over the fair value amounts assigned to the assets acquired and liabilities assumed represents the goodwill amount resulting from the acquisition. Determining the fair value of assets acquired and liabilities assumed involves the use of significant estimates and assumptions. See Note E - Business Combinations. New Accounting Pronouncements Recently Adopted In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) and issued ASU 2018-11 Leases (Topic 842): Targeted Improvements. The new standard(s) established a right-of-use ("ROU") model that requires a lessee to record an ROU asset and a corresponding lease liability on the balance sheet for all leases with terms greater than 12 months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition. Similarly, lessors will be required to classify leases as sales-type, finance or operating, with classification affecting the pattern of income recognition. Classification for both lessees and lessors will be based on an assessment of whether the lease risks and rewards, as well as substantive control, have been transferred through a lease contract. On January 1, 2019, we adopted the new accounting standard using the modified retrospective approach. We elected the package of practical expedients permitted under the transition guidance, which allowed us to account for our existing operating leases without reassessing (a) whether the contracts contain a lease under the new standard, (b) whether classification of the operating leases would be different in accordance with the new standard, or (c) whether the unamortized initial direct costs before transition adjustments would have met the definition of initial direct costs in the new standard at lease commencement. Adoption of the new standard resulted in the recognition of operating lease ROU assets of $223.0 million, which we have subsequently impaired during 2019 by $115.4 million, and lease liabilities of $222.7 million. The standard did not have a material impact on our consolidated statements of operations or cash flows. The comparative information has not been restated and continues to be reported under the accounting standards in effect for those periods. See Note S - Leases. In February 2018, the FASB issued Accounting Standards Update ASU 2018-02, Income Statement-Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. The ASU provides that the stranded tax effects from the Tax Cuts and Jobs Act of 2017 in accumulated other comprehensive loss may be reclassified to retained earnings. The ASU was effective January 1, 2019, with early adoption permitted. We adopted the new accounting standard on January 1, 2019, and we do not intend to exercise the option to reclassify stranded tax effects within accumulated other comprehensive income. New Accounting Pronouncements Not Yet Adopted In August 2018, the FASB issued ASU 2018-14, Compensation - Retirement Benefits - Defined Benefit Plans - General (Subtopic 715-20). The new guidance removes certain disclosure requirements for employers which sponsor defined benefit pension or other post-retirement plans, but also adds disclosure requirements for the weighted average interest crediting rates for cash balance plans and other plans with promised crediting rates and an explanation of the reasons for significant gains and losses related to changes in the benefit obligation for the period. The amendments also clarify disclosure requirements for the projected benefit obligation (PBO) and accumulated benefit obligation (ABO) and fair value of plan assets for plans with PBOs and ABOs in excess of plan assets. Entities should apply the amendments on a retrospective basis for all periods presented. The amendments in this Update are effective for public entities for fiscal years ending after December 15, 2020. We are currently evaluating the effect the guidance will have on our disclosures. In August 2018, the FASB issued ASU 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. The new guidance requires a customer in a cloud computing arrangement (i.e., hosting arrangement) that is a service contract to follow the internal-use software guidance in ASC 350-40 to determine which implementation costs to capitalize as assets or expense as incurred. Capitalized implementation costs related to a hosting arrangement that is a service contract will be amortized over the term of the hosting arrangement, beginning when the module or component of the hosting arrangement is ready for its intended use. The update is effective for calendar-year public business entities in 2020. We plan to adopt this guidance on a prospective basis and do not expect the adoption to have a significant impact on our Consolidated Statements of Operation. In November 2018, the FASB issued ASU 2018-19, Codification Improvements to Topic 326, Financial Instruments-Credit Losses. The amendments in this ASU clarified issues related to Topic 326. In Issue 1, the amendment in this ASU mitigate transition complexity by requiring that for nonpublic business entities the amendments in ASU 2016-13 are effective for fiscal years after December 15, 2021, including interim periods within those fiscal years. In Issue 2, the amendment clarifies that receivables arising from operating leases are not within the scope of Subtopic 326-20. Impairment of receivables arising from operating leases should be accounted for in accordance with Topic 842, Leases. The ASU is effective for all entities for fiscal years beginning after December 15, 2019, including interim periods therein. We expect the adoption of this standard will primarily impact our accounts receivable allowance estimating process, but do not expect a material impact to our consolidated financial statements. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. The amendments in this Update simplify the accounting for income taxes by removing several exceptions and also simplify the accounting for income taxes by requiring that an entity recognize a franchise tax (or similar tax) that is partially based on income as an income-based tax and account for any incremental amount incurred as a non-income-based tax, requiring that an entity evaluate when a step up in the tax basis of goodwill should be considered part of the business combination in which the book goodwill was originally recognized and when it should be considered a separate transaction, specifying that an entity is not required to allocate the consolidated amount of current and deferred tax expense to a legal entity that is not subject to tax in its separate financial statements (however, an entity may elect to do so on an entity-by-entity basis) for a legal entity that is both not subject to tax and disregarded by the taxing authority, requiring that an entity reflect the effect of an enacted change in tax laws or rates in the annual effective tax rate computation in the interim period that includes the enactment date, and making minor codification improvements for income taxes related to employee stock ownership plans and investments in qualified affordable housing projects accounted for using the equity method. For public business entities, the amendments in this Update are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. We are currently evaluating the effect that the guidance will have on our financial statements and related disclosures.

Earnings Per Share

12 Months Ended

Dec. 31, 2019

Earnings Per Share [Abstract]

EARNINGS PER SHARE

NOTE C—EARNINGS PER SHARE

Basic earnings per common share is computed by dividing income available to common stockholders by the weighted average number of common shares outstanding for the period. Diluted earnings per common share is computed similarly to basic earnings per common share except that the weighted average number of common shares outstanding is increased to include the number of additional common shares that would have been outstanding if the potentially dilutive common shares had been issued.

The following table shows the computation of basic and diluted earnings per share for the years ended December 31, 2019, 2018 and 2017:



In thousands, except per share amounts	Year ended December 31,
	2019			2018			2017
Numerator:
Net (loss) income attributable to U.S. Silica Holdings, Inc.	$	(329,082	)	$	(200,808	)	$	145,206

Denominator:
Weighted average shares outstanding	73,253			76,453			81,051
Diluted effect of stock awards	—			—			909
Weighted average shares outstanding assuming dilution	73,253			76,453			81,960

(Loss) earnings per share attributable to U.S. Silica Holdings, Inc.:
Basic (loss) earnings per share	$	(4.49	)	$	(2.63	)	$	1.79
Diluted (loss) earnings per share	$	(4.49	)	$	(2.63	)	$	1.77

Potentially dilutive shares (in thousands) of 68 and 443 for the year ended December 31, 2019 and 2018, respectively, were excluded from the calculation of diluted weighted average shares outstanding and diluted earnings per share because we were in a loss position. Certain stock options, restricted stock awards and performance share units were excluded from the computation of diluted earnings per share because their effect would have been anti-dilutive. Such stock awards (in thousands) excluded from the calculation of diluted earnings (loss) per common share were as follows:



	Year ended December 31,
	2019	2018	2017
Stock options excluded	711	574	195
Restricted stock and performance share units awards excluded	1,298	155	305

Capital Structure and Accumulated Other Comprehensive Income (Loss)

12 Months Ended

Dec. 31, 2019

Equity [Abstract]

CAPITAL STRUCTURE AND ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)

NOTE D—CAPITAL STRUCTURE AND ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)

Common Stock

Our Amended and Restated Certificate of Incorporation authorizes up to 500,000,000 shares of common stock, par value of $0.01. Subject to the rights of holders of any series of preferred stock, all of the voting power of the stockholders of Holdings shall be vested in the holders of the common stock. There were 82,601,926 shares issued and 73,601,950 shares outstanding at December 31, 2019. There were 81,811,977 shares issued and 73,148,853 shares outstanding at December 31, 2018.

During the year ended December 31, 2019, our Board of Directors declared quarterly cash dividends as follows:



Dividends per Common Share		Declaration Date	Record Date	Payable Date
$	0.0625	February 15, 2019	March 14, 2019	April 4, 2019
$	0.0625	May 13, 2019	June 14, 2019	July 5, 2019
$	0.0625	July 18, 2019	September 13, 2019	October 3, 2019
$	0.0625	November 12, 2019	December 13, 2019	January 3, 2020

All dividends were paid as scheduled.

Any determination to pay dividends and other distributions in cash, stock, or property by Holdings in the future will be at the discretion of our Board of Directors and will be dependent on then-existing conditions, including our business and financial condition, results of operations, liquidity, capital requirements, contractual restrictions including restrictive covenants contained in our debt agreements, and other factors. Additionally, because we are a holding company, our ability to pay dividends on our common stock may be limited by restrictions on the ability of our subsidiaries to pay dividends or make distributions to us, including restrictions under the terms of the agreements governing our indebtedness.

Preferred Stock

Our Amended and Restated Certificate of Incorporation authorizes our Board of Directors to issue up to 10,000,000 shares, in the aggregate, of preferred stock, par value of $0.01 in one or more series, to fix the powers, preferences and other rights of such series, and any qualifications, limitations or restrictions thereof, including the dividend rate, conversion rights, voting rights, redemption rights and liquidation preference, and to fix the number of shares to be included in any such series, without any further vote or action by our stockholders.

There were no shares of preferred stock issued or outstanding at December 31, 2019 or December 31, 2018. At present, we have no plans to issue any preferred stock.

Share Repurchase Program

We are authorized by our Board of Directors to repurchase shares of our outstanding common stock from time to time on the open market or in privately negotiated transactions. Stock repurchases, if any, will be funded using our available liquidity. The timing and amount of stock repurchases will depend on a variety of factors, including the market conditions as well as corporate and regulatory considerations.

In May 2018, our Board of Directors authorized the repurchase of up to $200 million of our common stock. As of December 31, 2019, we have repurchased a total of 5,036,139 shares of our common stock at an average price of $14.59 and have $126.5 million of remaining availability under this program.

Accumulated Other Comprehensive Loss

Accumulated other comprehensive loss consists of fair value adjustments associated with cash flow hedges, accumulated adjustments for net experience losses and prior service cost related to employee benefit plans and foreign currency translation adjustments, net of tax. The following table presents the changes in accumulated other comprehensive loss by component (in thousands) during the year ended December 31, 2019:



	For the Year Ended December 31, 2019
	Unrealized loss on cash flow hedges			Foreign currency translation adjustments			Pension and other post-retirement benefits liability			Total
Beginning Balance	$	(1,621	)	$	(620	)	$	(12,779	)	$	(15,020	)
Other comprehensive loss before reclassifications	(1,432		)	(188		)	(4,450		)	(6,070		)
Amounts reclassed from accumulated other comprehensive loss	—			—			1,236			1,236
Ending Balance	$	(3,053	)	$	(808	)	$	(15,993	)	$	(19,854	)

Any amounts reclassified from accumulated other comprehensive loss related to cash flow hedges are included in interest expense in our Consolidated Statements of Operations and amounts reclassified related to pension and other post-retirement benefits are included in the computation of net periodic benefit costs at their pre-tax amounts.

Business Combinations

12 Months Ended

Dec. 31, 2019

Business Combinations [Abstract]

BUSINESS COMBINATIONS

NOTE E—BUSINESS COMBINATIONS

Goodwill

Goodwill represents the excess of the purchase price over the fair value of the underlying net assets acquired.

Trade Names

A trade name is a legally protected trade or similar mark. Acquired trade names are valued using an income method approach, generally the relief-from-royalty valuation method. The method uses a royalty rate based on comparable marketplace royalty agreements for similar types of trade names and applies it to the after-tax discounted free cash flow attributed to the trade name. The discount rate used is based on an estimated weighted average cost of capital and the anticipated risk for intangible assets.

The valued trade names have an indefinite life based on our plans and expectations for the trade names going forward and are reviewed for impairment under ASC 350-30-35.

Intellectual Property and Technology

Intellectual property and technology (“IP”) is a design, work or invention that is the result of creativity to which one has ownership rights that may be protected through a patent, copyright, trademark or service mark. IP is valued using the relief from royalty valuation method. The method uses a royalty rate based on comparable market-place royalty agreements for similar types of IP and applies it to the after-tax discounted free cash flow attributed to the IP. The discount rate used is based on an estimated weighted average cost of capital and the anticipated risk for intangible assets.

The IP is amortized following the pattern in which the expected benefits will be consumed or otherwise used up over each component’s useful life, based on our plans and expectations for the IP going forward, which is generally the underlying IP’s legal expiration dates. IP is reviewed for impairment under ASC 360-10.

Customer Relationships

Customer relationships are intangible assets that consist of historical and factual information about customers and contacts collected from repeat transactions with customers, with or without any underlying contracts. The information is generally organized as customer lists or customer databases. We have the expectation of repeat patronage from these customers based on the customers’ historical purchase activity, which creates the intrinsic value over a finite period of time and translates into the expectation of future revenue, income, and cash flow.

Customer relationships are valued using projected operating income, adjusted for estimated future existing customer growth less estimated future customer attrition, net of charges for net tangible assets, IP charge, trade name charge and work force. The concluded value is the after-tax discounted free cash flow. Customer relationships are reviewed for impairment under ASC 360-10.

2018 Acquisition:

On May 1, 2018, we completed the acquisition of all of the outstanding capital stock of EP Acquisition Parent, Inc., a Delaware corporation (“EPAP”), and the ultimate parent of EP Minerals, LLC ("EPM"). Contemporaneous with the merger, EPAP was renamed EP Minerals Holdings, Inc. ("EPMH"). The consideration paid consisted of $743.2 million of cash, net of cash acquired of $19.1 million, including $0.5 million of post-closing adjustments. EPM is a global producer of engineered materials derived from industrial minerals, including diatomaceous earth, clay (calcium bentonite and calcium montmorillonite) and perlite. EPM's industrial minerals are used as filter aids, absorbents and functional additives for a variety of industries including food and beverage, biofuels, recreational water, oil and gas, farm and home, landscape, sports turf, paint, plastics, and insecticides. The acquisition of EPM increased our industrial materials product offering in our Industrial & Specialty Products business segment.

We have accounted for the acquisition of EPMH under the acquisition method of accounting in accordance with ASC 805, Business Combinations, and have accounted for measurement period adjustments in accordance with ASU 2015-16, Simplifying the Accounting for Measurement-Period Adjustments. Estimates of fair value included in the Consolidated Financial Statements represent our best estimates and valuations. In accordance with the acquisition method of accounting, the allocation of consideration value was subject to adjustment until we completed our analysis in the second quarter of 2019.

The following table sets forth the final allocation of the purchase price to EPMH's identifiable tangible and intangible assets acquired and liabilities assumed, including measurement period adjustments (in thousands):



Final allocation of purchase price:	Estimate as of December 31, 2018		Measurement Period Adjustments			Purchase Price Allocation
Accounts receivable, net	$	43,305	$	—		$	43,305
Inventories	86,112		—			86,112
Property, plant and mine development	148,495		(1,937		)	146,558
Mineral rights	419,469		(10,580		)	408,889
Identifiable intangible assets - finite lived	10,270		(1,500		)	8,770
Identifiable intangible assets - indefinite lived	38,050		(1,250		)	36,800
Prepaids and deposits	2,072		(245		)	1,827
Other assets	7,474		—			7,474
Goodwill	150,628		12,184			162,812
Total assets acquired	905,875		(3,328		)	902,547
Accounts payable	13,435		—			13,435
Accrued expenses and other current liabilities	10,304		—			10,304
Deferred tax liabilities	122,811		(3,328		)	119,483
Long term obligations	16,076		—			16,076
Total liabilities assumed	$	162,626	$	(3,328	)	$	159,298
Net assets acquired	$	743,249	$	—		$	743,249

The acquired intangible assets and the related estimated useful lives consist of the following:



	Approximate Fair Value		Estimated Useful Life
	(in thousands)		(in years)
Technology and intellectual property	$	1,400	15
Customer relationships	7,370		15
Total identifiable intangible assets - finite lived	$	8,770

Trade names	$	36,800
Total identifiable intangible assets - indefinite lived	$	36,800

Goodwill represents the excess of the purchase price over the fair value of the underlying net assets acquired. Goodwill in this transaction is attributable to planned growth in our industrial materials product offering in our Industrial & Specialty Products business segment. Intangibles and goodwill are not expected to be deductible for tax purposes.

Our Income Statement included revenue of $158.8 million and a net loss of $0.6 million for the year ended December 31, 2018, associated with EPMH following the date of acquisition. We incurred $13.6 million of acquisition-related charges, excluding debt issuance costs, for the year ended December 31, 2018, which are included in selling, general and administrative expenses on our Income Statement.

Unaudited Pro Forma Results

The results of EPMH's operations have been included in the Consolidated Financial Statements subsequent to the acquisition date. EPMH's fiscal year end was November 30 and the Company's fiscal year end was December 31. Under SEC regulations, if a target's fiscal year end varies by more than 93 days from the acquirer's fiscal year end, it is required to adjust interim periods until it is within 93 days. Since EPMH’s fiscal year end was within 93 days of the Company's fiscal year end, no adjustment is necessary and EPMH’s fiscal year end and interim period ends are used as if they coincided with the Company's fiscal year end and interim period end. The following unaudited pro forma consolidated financial information reflects the results of operations as if the EPMH acquisition had occurred on January 1, 2017, after giving effect to certain purchase accounting adjustments. Material non-recurring transaction costs attributable to the business combination were $15.2 million. Pro forma net income includes incremental interest expense due to the related debt financing, incremental depreciation and depletion expense related to the fair value adjustment of property, plant and mine development, amortization expense related to identifiable intangible assets, and tax expense related to the combined tax provisions. This information does not purport to be indicative of the actual results that would have occurred if the acquisition had actually been completed on the date indicated, nor is it necessarily indicative of the future operating results or the financial position of the combined company (in thousands, except per share amounts):



	For the year ended December 31,
	2018			2017
Sales	$	1,659,775		$	1,454,070
Net (loss) income	$	(179,220	)	$	116,899
Basic (loss) earnings per share	$	(2.34	)	$	1.44
Diluted (loss) earnings per share	$	(2.34	)	$	1.43

2017 Acquisitions:

White Armor Acquisition:

On April 1, 2017, we completed the acquisition of White Armor, a product line of cool roof granules used in industrial roofing applications, for cash consideration of $18.6 million. The final purchase price was allocated to goodwill of approximately $3.9 million, identifiable intangible assets of $12.8 million and other net assets of approximately $1.9 million.

Goodwill in this transaction is attributable to planned growth in our specialty industrial sand business segment. The goodwill amount is included in our Industrial & Specialty Products business segment. Identifiable definite lived intangibles, including customer relationships, and goodwill are expected to be deductible for tax purposes.

We incurred $0.2 million of acquisition-related charges which are included in selling, general and administrative expenses during the year ended December 31, 2017. Revenue and earnings for White Armor after the acquisition date are not presented as the business was integrated into our operations subsequent to the acquisition and therefore impracticable to quantify.

MS Sand Acquisition:

On August 16, 2017, we completed the acquisition of Mississippi Sand, LLC ("MS Sand"), a Missouri limited liability company, for cash consideration of approximately $95.4 million, net of cash acquired of $2.2 million. As is normal and customary, subsequent adjustments were made including $(0.5) million of net working capital adjustments plus an additional $6.1 million consideration paid related to a pre-existing contracted asset sale, which was entered into prior to our acquisition, for total cash consideration of $101.0 million. MS Sand is a frac sand mining and logistics company based in St. Louis, Missouri. The acquisition of MS Sand increased our regional frac sand product offering in our Oil & Gas Proppants business segment.

We have accounted for the acquisition of MS Sand under the acquisition method of accounting in accordance with ASC 805, Business Combinations, and have accounted for measurement period adjustments in accordance with ASU 2015-16, Simplifying the Accounting for Measurement-Period Adjustments. In accordance with the acquisition method of accounting, the allocation of consideration value was subject to adjustment until we completed our analysis in the third quarter of 2018.

The following table sets forth the final allocation of the purchase price to MS Sands' identifiable tangible and intangible assets acquired and liabilities assumed, including measurement period adjustments (in thousands):



	Estimate as of December 31, 2017		Measurement Period Adjustments			Purchase Price Allocation
Accounts receivable	$	11,201	$	—		$	11,201
Inventories	8,067		—			8,067
Other current assets	362		—			362
Assets held for sale	9,453		—			9,453
Property, plant and mine development	27,458		—			27,458
Mineral rights	26,300		(2,800		)	23,500
Other non-current assets	1,136		—			1,136
Goodwill	22,522		2,800			25,322
Customer relationships	1,840		—			1,840
Total assets acquired	108,339		—			108,339
Accounts payable and accrued expenses	3,761		—			3,761
Unfavorable leasehold positions	2,237		—			2,237
Notes Payable	866		—			866
Other long term liabilities	—		—			—
Asset retirement obligations	474		—			474
Total liabilities assumed	7,338		—			7,338
Net assets acquired	$	101,001	$	—		$	101,001

The acquired intangible assets and the related estimated useful lives consist of the following:



	Approximate Fair Value		Estimated Useful Life
	(in thousands)		(in years)
Customer relationships	$	1,840	15

Goodwill in this transaction is attributable to planned growth in our regional frac sand product offering in our Oil & Gas Proppants business segment. The goodwill amount is included in our Oil & Gas Proppants business segment. Identifiable definite lived intangibles, including customer relationships, and goodwill are expected to be deductible for tax purposes.

We incurred $1.0 million of acquisition-related charges which are included in selling, general and administrative expenses. Revenue and earnings for MS Sand after the acquisition date are not presented as the business was integrated into our operations subsequent to the acquisition and therefore impracticable to quantify.

Unaudited Pro Forma Results

The results of MS Sand’s operations have been included in the Consolidated Financial Statements subsequent to the acquisition dates. The following unaudited pro forma consolidated financial information reflects the results of operations as if the MS Sand Acquisition had occurred on January 1, 2016, after giving effect to certain purchase accounting adjustments. These adjustments mainly include incremental depreciation expense related to the fair value adjustment of property, plant, equipment and mine development, amortization expense related to identifiable intangible assets and tax expense related to the combined tax provisions. This information does not purport to be indicative of the actual results that would have occurred if the acquisition had actually been completed on the date indicated, nor is it necessarily indicative of the future operating results or the financial position of the combined company (in thousands, except per share amounts):



	For the year ended December 31,
	2017
Sales	$	1,287,202
Net income	$	143,604
Basic earnings per share	$	1.77
Diluted earnings per share	$	1.75

Accounts Receivable

12 Months Ended

Dec. 31, 2019

Receivables [Abstract]

ACCOUNTS RECEIVABLE

NOTE F—ACCOUNTS RECEIVABLE

At December 31, 2019 and December 31, 2018, accounts receivable (in thousands) consisted of the following:



	December 31, 2019			December 31, 2018
Trade receivables	$	178,182		$	198,435
Less: Allowance for doubtful accounts	(8,984		)	(6,751		)
Net trade receivables	169,198			191,684
Other receivables⁽¹⁾	13,040			23,802
Total accounts receivable	$	182,238		$	215,486



(1	)	At December 31, 2019, other receivables include $8.1 million of refundable alternative minimum tax credits. At December 31, 2018, other receivables included $16.0 million of refundable alternative minimum tax credits that were refunded during the third quarter of 2019.

Changes in our allowance for doubtful accounts (in thousands) during the years ended December 31, 2019 and 2018 were as follows:



	December 31, 2019			December 31, 2018
Beginning balance	$	6,751		$	7,100
Bad debt provision	3,466			315
Write-offs	(1,233		)	(664		)
Ending balance	$	8,984		$	6,751

Our ten largest customers accounted for approximately 43%, 48% and 58% of total sales during the year ended December 31, 2019, 2018 and 2017, respectively. Sales to one of our customers accounted for 11% of our total sales during the year ended December 31, 2019. Sales to one of our customers accounted for 15% of our total sales during the year ended December 31, 2018. Sales to two of our customers accounted for 15% and 12% of our total sales during the year ended December 31, 2017. No other customers accounted for 10% or more of our total sales. At December 31, 2019, one of our customers' accounts receivable represented 12% of our total trade accounts receivable, net of allowance. At December 31, 2018, the same customer's accounts receivable represented 18% of our total trade accounts receivable, net of allowance. No other customers accounted for 10% or more of our total trade accounts receivable.

Inventories

12 Months Ended

Dec. 31, 2019

Inventory Disclosure [Abstract]

INVENTORIES

NOTE G—INVENTORIES

At December 31, 2019 and December 31, 2018, inventories (in thousands) consisted of the following:



	December 31, 2019		December 31, 2018
Supplies	$	47,277	$	41,453
Raw materials and work in process	41,167		68,474
Finished goods	35,988		52,160
Total inventories	$	124,432	$	162,087

The decrease in inventories is primarily attributable to the amortization of inventory fair value step-up from purchase accounting as well as from write-offs of obsolete inventory, write-downs of inventory to net realizable value and impairments of unused inventory at frac sand plants we idled. See Note Z - Impairments for additional information.

Property, Plant and Mine Development

12 Months Ended

Dec. 31, 2019

Property, Plant and Equipment [Abstract]

PROPERTY, PLANT AND MINE DEVELOPMENT

NOTE H—PROPERTY, PLANT AND MINE DEVELOPMENT

At December 31, 2019 and December 31, 2018, property, plant and mine development (in thousands) consisted of the following:



	December 31, 2019			December 31, 2018
Mining property and mine development	$	794,899		$	995,759
Asset retirement cost	18,260			12,732
Land	57,082			55,502
Land improvements	73,203			67,729
Buildings	69,112			64,515
Machinery and equipment	1,152,898			958,357
Furniture and fixtures	4,068			3,599
Construction-in-progress	54,675			167,933
	2,224,197			2,326,126
Accumulated depletion, depreciation, amortization and impairment charges	(706,610		)	(499,823		)
Total property, plant and mine development, net	$	1,517,587		$	1,826,303

Depreciation, depletion, and amortization expense related to property, plant and mine development for the years ended December 31, 2019 and 2018 was $168.6 million and $139.1 million, respectively. At December 31, 2019 and December 31, 2018, the aggregate cost of machinery and equipment acquired under finance leases was $0.3 million and $0.5 million, respectively, reduced by accumulated depreciation of $0.2 million and $0.2 million, respectively. The amount of interest costs capitalized in property, plant and mine development was $2.0 million and $6.7 million for the year ended December 31, 2019 and 2018, respectively.

During 2019, impairment charges of approximately $243.1 million were recorded mainly related to facilities that have reduced capacity or have been idled, including Tyler, Texas, Sparta, Wisconsin, and Utica, Illinois. During 2018, impairment charges of approximately $109.9 million were recorded mainly related to facilities that have reduced capacity or have been idled, including Voca, Texas, Fairchild, Wisconsin, Rochelle, Illinois, and Peru, Illinois. These charges relate to the Oil & Gas Segment and are recorded in "Goodwill and other asset impairments" in the Consolidated Statements of Operations. See Note Z - Impairments for additional information.

During 2019, management approved the disposal of certain non-operating parcels of land. The assets had a combined carrying value of approximately $1.3 million. The proceeds of the disposals were expected to exceed the net carrying value of the assets and, accordingly, no impairment loss was recognized on these assets held for sale. The assets were previously classified as Land, therefore, no adjustments were needed for depreciation of these assets. During the fourth quarter of 2019, we sold a portion of these assets at a gain of $0.6 million, which was recorded in Other income, net, including interest income in the Consolidated Statements of Operations. At December 31, 2019, the remaining balance of assets held for sale included in Prepaid expenses and other current assets in the Consolidated Balance Sheets is $0.1 million, which we expect to dispose of within one year of the balance sheet date.

On March 21, 2018, we completed the sale of three transload facilities located in the Permian, Eagle Ford, and Marcellus Basins to CIG Logistics (“CIG”) for total consideration of $86.1 million, including the assumption by CIG of $2.2 million of Company obligations. Total cash consideration was $83.9 million. The consideration includes receipt of a vendor incentive from CIG to enter into master transloading service arrangements. Of the total consideration, $25.8 million was allocated to the fair value of the transload facilities, which had a net book value of $20.0 million and resulted in a gain on sale of $5.8 million. The consideration included a related asset retirement obligation of $2.1 million and an equipment note of $0.1 million assumed by CIG. In addition, $60.3 million of the consideration received in excess of the facilities' fair value was allocated to vendor incentives to be recognized as a reduction of costs using a service-level methodology over the contract lives of the transloading service arrangements. At December 31, 2019, vendor incentives of $26.6 million were classified in accounts payable and accrued expenses on our balance sheet. At December 31, 2018, vendor incentives of $12.5 million and $33.8 million were classified in accounts payable and accrued expenses and in other long-term obligations, respectively, on our balance sheet.

Separately, on March 21, 2018, we accrued $7.9 million in contract termination costs for facilities contracts operated by third-parties, which will not transfer to CIG. During the second quarter of 2018, as a result of the final settlement of these contracts, we recorded a $2.7 million credit in selling, general and administrative expenses on our Income Statement.

Goodwill and Intangible Assets

12 Months Ended

Dec. 31, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

GOODWILL AND INTANGIBLE ASSETS

NOTE I—GOODWILL AND INTANGIBLE ASSETS

The changes in the carrying amount of goodwill (in thousands) by business segment consisted of the following:



	Oil & Gas Proppants Segment			Industrial & Specialty Products Segment		Total
Balance at December 31, 2017	247,467			24,612		272,079

MS Sand acquisition measurement period adjustment	2,800			—		2,800
EPMH acquisition and measurement period adjustment	—			150,628		150,628
Oil & Gas Sand impairment	(164,167		)	—		(164,167		)

Goodwill	250,267			175,240		425,507
Impairment losses	(164,167		)	—		(164,167		)
Balance at December 31, 2018	86,100			175,240		261,340

EPMH acquisition measurement period adjustment	—			12,184		12,184
Balance at December 31, 2019	$	86,100		$	187,424	$	273,524

Goodwill and trade names are evaluated for impairment annually as of October 31, or more frequently when indicators of impairment exist. We evaluated events and circumstances since the date of our last qualitative assessment, including macroeconomic conditions, industry and market conditions, and our overall financial performance. After assessing the totality of the events and circumstances, we determined that it was not more likely than not that the fair value of our reporting units was less than their carrying amount and no impairment existed related to goodwill or trade names as of December 31, 2019.

During 2018, subsequent to our annual impairment test, we experienced a declining shift in demand for Northern White sand caused by some of our customers shifting to local in-basin frac sands with lower logistics costs. Our largest customer at our Voca, Texas plant did not renew their contract, instead opting to sign a new contract with us for local in-basin frac sand. Additionally, Northern White Sand operations and reserves in Fairchild, Wisconsin and Peru, Illinois experienced a similar significant fourth quarter decline in demand due to customers' shift to local in-basin sand closer to their operations.

As a result of these triggering events, we performed a quantitative analysis and determined that the goodwill of our Oil & Gas Sand reporting unit was impaired. We recognized goodwill impairment charges of $164.2 million and intangible asset impairment charges related to trade names of $4.5 million during the fourth quarter of 2018. These impairment charges were recorded in the "Goodwill and other asset impairments" caption of our Consolidated Statements of Operations. The fair value of our reporting units was determined using a combination of the discounted cash flow method and the market multiples approach.

The changes in the carrying amount of intangible assets (in thousands) consisted of the following:



	December 31, 2019										December 31, 2018
	Gross Carrying Amount		Accumulated Amortization			Impairments			Net		Gross Carrying Amount		Accumulated Amortization			Impairments			Net

Technology and intellectual property	$	86,183	$	(17,080	)	—			$	69,103	$	83,616	$	(11,168	)	—			$	72,448
Customer relationships	68,599		(18,737		)	$	(1,240	)	48,622		68,664		(13,826		)	—			54,838
Total definite-lived intangible assets:	$	154,782	$	(35,817	)	$	(1,240	)	$	117,725	$	152,280	$	(24,994	)	$	—		$	127,286
Trade names	65,390		—			—			65,390		71,118		—			(4,478		)	66,640
Other	700		—			—			700		700		—			—			700
Total intangible assets:	$	220,872	$	(35,817	)	$	(1,240	)	$	183,815	$	224,098	$	(24,994	)	$	(4,478	)	$	194,626

We recorded a $1.2 million impairment of customer relationships and a $4.5 million impairment of trade names as of December 31, 2019 and 2018, respectively, in the Oil & Gas Segment. These impairment charges were recorded in the "Goodwill and other asset impairments" caption of our Consolidated Statements of Operations. See Note Z - Impairments for additional information.

Estimated useful life of technology and intellectual property is 15 years. Estimated useful life of customer relationships is a range of 13 - 15 years.

During the first quarter of 2019, measurement period adjustments related to the Company's EPMH acquisition decreased the gross carrying amounts of the technology and intellectual property by $1.5 million and the trade names by $1.3 million. See Note E - Business Combinations.

Amortization expense was $10.8 million, $9.7 million and $8.8 million for the years ended December 31, 2019, 2018, and 2017, respectively.

The estimated amortization expense related to definite-lived intangible assets (in thousands) for the five succeeding years is as follows:



2020	$	10,863
2021	10,861
2022	10,846
2023	10,841
2024	10,843

Accounts Payable and Accrued Liabilities

12 Months Ended

Dec. 31, 2019

Payables and Accruals [Abstract]

ACCOUNTS PAYABLE AND ACCRUED LIABILITIES

NOTE J—ACCOUNTS PAYABLE AND ACCRUED LIABILITIES

At December 31, 2019 and 2018, accounts payable and accrued liabilities (in thousands) consisted of the following:



	December 31,
	2019		2018
Trade payables	$	181,029	$	166,296
Accrued salaries and wages	12,385		12,291
Accrued vacation liability	3,053		3,503
Current portion of liability for pension and post-retirement benefits	2,993		2,708
Accrued healthcare liability	4,078		2,702
Accrued property taxes and sales taxes	4,070		4,490
Vendor incentives	26,617		12,508
Other accrued liabilities	14,012		11,902
Accounts payable and accrued liabilities	$	248,237	$	216,400

Other accrued liabilities consist of employer related expenses, dividends payable, royalties payable, accrued interest payable, and other items.

Certain reclassifications of prior year's amounts have been made to conform to the current year presentation. In conforming to the current year presentation, trade payables were decreased by $12.5 million and included in the vendor incentives line item. See Note H - Property, Plant and Mine Development for more information related to vendor incentives.

Debt

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

DEBT

NOTE K—DEBT

At December 31, 2019 and 2018, debt (in thousands) consisted of the following:



	December 31, 2019			December 31, 2018
Senior secured credit facility:
Revolver expiring May 1, 2023 (7.75% at December 31, 2019 and 8.50% at December 31, 2018)	$	—		$	—
Term Loan facility—final maturity May 1, 2025 (5.81% at December 31, 2019 and 6.56% December 31, 2018)	1,247,600			1,270,400
Less: Unamortized original issue discount	(5,412		)	(6,511		)
Less: Unamortized debt issuance cost	(25,390		)	(31,310		)
Note payable secured by royalty interest	10,438			26,511
Insurance financing notes payable	5,055			—
Equipment notes payable	87			321
Finance leases	70			344
Total debt	1,232,448			1,259,755
Less: current portion	(18,463		)	(13,327		)
Total long-term portion of debt	$	1,213,985		$	1,246,428

Senior Secured Credit Facility

On May 1, 2018, we entered into a Third Amended and Restated Credit Agreement (the "Credit Agreement"), which increased our existing senior debt by entering into a new $1.380 billion senior secured Credit Facility, consisting of a $1.280 billion term loan (the "Term Loan") and a $100 million revolving credit facility (the "Revolver") (collectively the "Credit Facility") that may also be used for swingline loans or letters of credit, and we may elect to increase the term loan in accordance with the terms of the Credit Agreement. Borrowings under the Credit Agreement will bear interest at variable rates as determined at our election, at LIBOR or a base rate, in each case, plus an applicable margin. In addition, under the Credit Agreement, we are required to pay a per annum facility fee and fees for letters of credit. The Credit Agreement is secured by substantially all of our assets and of our domestic subsidiaries' assets and a pledge of the equity interests in such entities. The Term Loan matures on May 1, 2025, and the Revolver expires on May 1, 2023. We capitalized $38.7 million in debt issuance costs and original issue discount as a result of the new Credit Agreement.

The Credit Agreement contains covenants that, among other things, limit our ability, and certain of our subsidiaries' abilities, to create, incur or assume indebtedness and liens, to make acquisitions or investments, to sell assets and to pay dividends. The Credit Agreement also requires us to maintain a consolidated leverage ratio of no more than 3.75:1.00 as of the last day of any fiscal quarter whenever usage of the Revolver (other than certain undrawn letters of credit) exceeds 30% of the Revolver commitment. These covenants are subject to a number of important exceptions and qualifications. The Credit Agreement includes events of default and other affirmative and negative covenants that are usual for facilities and transactions of this type. As of December 31, 2019, and 2018, we are in compliance with all covenants in accordance with our senior secured Credit Facility.

Term Loan

At December 31, 2019, contractual maturities of our senior secured Credit Facility (in thousands) are as follows:



2020	$	12,800
2021	12,800
2022	12,800
2023	12,800
2024	12,800
Thereafter	1,183,600
Total	$	1,247,600

During the third quarter of 2019, we repurchased outstanding debt under the Term Loan in the amount of $10 million at a rate of 95.5%. Debt issuance costs and original issue discount were recalculated with the reduced future debt payments, and additional costs of approximately $0.4 million were expensed. As a result, we recorded a gain on extinguishment of debt in the amount of $0.1 million. The gain on extinguishment was recorded in Other income, net, including interest income in the Consolidated Statements of Operations.

Revolving Line-of-Credit

We have a $100.0 million Revolver with zero drawn and $6.5 million allocated for letters of credit as of December 31, 2019, leaving $93.5 million available under the Revolver. Based on our consolidated leverage ratio of 4.30:1.00 as of December 31, 2019, we may draw up to $30.0 million without the consent of our lenders. With the consent of our lenders, we have access to the full availability of the Revolver.

Note Payable Secured by Royalty Interest

In conjunction with the acquisition of New Birmingham, Inc. in August 2016, we assumed a note payable secured by a royalty interest. The monthly royalty payment is calculated based on future tonnages and sales related to the sand shipped from our Tyler, Texas facility. The note payable is due by June 30, 2032. The note does not provide a stated interest rate. The minimum payments (in thousands) for the next five years required by the note are as follows:



2020	$	454
2021	378
2022	434
2023	499
2024	570
Thereafter	8,103

Under this agreement once a certain number of tons have been shipped from the Tyler facility, the minimum payments will decrease to $0.5 million per year, subject to proration in the period this threshold is met.

The royalty note payable fair value was estimated to be $22.5 million on the acquisition date. The estimate was made using a discounted cash flow model, which calculated the present value of projected future cash payments required under the agreement using a discounted rate of 14%. As of December 31, 2019, the note payable had a fair value of $10.4 million. The decrease in fair value of the note payable amount is due to changes in our estimate of future tonnages and sales related to the sand shipped from our Tyler, Texas facility. We no longer expect any future tonnages and sales related to this facility, which has been idled. The note payable has been reduced to the discounted value of the future minimum payments as required by contract. These changes in estimate resulted in gains that were recorded in Other income, net, including interest income in the Consolidated Statements of Operations. Gains in the amount of $16.9 million were recorded during 2019. The effective interest rate based on the updated projected future cash payments was 14% at December 31, 2019. Other changes in fair value of the note payable amount may result if estimates of future tonnages and sales increase or decrease.

Insurance Financing Notes Payable

During the third quarter of 2019, we renewed our insurance policies and financed the payments through notes payable with a stated interest rate of 4.5%. These payments will be made in installments throughout a ten-month period and, as such, have been classified as current debt. As of December 31, 2019, the notes payable had a balance of $5.1 million.

Deferred Revenue

12 Months Ended

Dec. 31, 2019

Deferred Revenue Disclosure [Abstract]

DEFERRED REVENUE

NOTE L—DEFERRED REVENUE

We enter into certain customer supply agreements which give the customers the right to purchase certain products for a discounted price at certain volumes over an average initial contract term of one to fifteen years. The advance payments represent future purchases and are recorded as deferred revenue, recognized as revenue over the contract term of each supply agreement. During the year ended December 31, 2019 we received advances of $12.2 million. At December 31, 2019 and 2018, the total deferred revenue balance was $50.6 million and $113.3 million, respectively, of which $15.1 million and $31.6 million was classified as current on our Balance Sheets.

The decrease in the current year balance is partially attributable to revenue recognized as variable consideration from shortfall penalties assessed to multiple customers according to contract terms. In some cases, amounts recorded are estimates

which are in negotiation and may increase or decrease. We believe this is the best estimate of revenue to recognize as of December 31, 2019.

NOTE U— REVENUE

We consider sales disaggregated at the product and service level by business segment to depict how the nature, amount, timing and uncertainty of revenues and cash flow are impacted by changes in economic factors. The following table reflects our sales disaggregated by major source for the year ended December 31, 2019 (in thousands):



	Year Ended December 31, 2019						Year Ended December 31, 2018
Category	Oil & Gas Proppants		Industrial & Specialty Products		Total Sales		Oil & Gas Proppants		Industrial & Specialty Products		Total Sales
Product	$	704,516	$	463,956	$	1,168,472	$	888,509	$	394,290	$	1,282,799
Service	306,005		—		306,005		294,482		17		294,499
Total Sales	$	1,010,521	$	463,956	$	1,474,477	$	1,182,991	$	394,307	$	1,577,298

The following tables reflect the changes in our contract assets, which we classify as unbilled receivables and our contract liabilities, which we classify as deferred revenues, for the year ended December 31, 2019 (in thousands):



	Unbilled Receivables
	December 31, 2019			December 31, 2018
Beginning Balance	$	90		$	5,245
Reclassifications to billed receivables	(3,983		)	(11,157		)
Revenues recognized in excess of period billings	4,037			6,002
Ending Balance	$	144		$	90



	Deferred Revenue
	December 31, 2019			December 31, 2018
Beginning Balance	$	113,319		$	118,414
Revenues recognized from balances held at the beginning of the period	(65,225		)	(33,381		)
Revenues deferred from period collections on unfulfilled performance obligations	12,225			31,625
Revenues recognized from period collections	(9,685		)	(3,339		)
Ending Balance	$	50,634		$	113,319

We have elected to use the practical expedients allowed under ASC 606-10-50-14, pursuant to which we have excluded disclosures of transaction prices allocated to remaining performance obligations and when we expect to recognize such revenue. The majority of our remaining performance obligations are primarily comprised of unfulfilled product, transportation service, and labor service orders, all of which hold a remaining duration of less than one year. The long term portion of deferred revenue primarily represents a combination of refundable and nonrefundable customer prepayments for which related current performance obligations do not yet exist, but are expected to arise, before the expiration of the contract. Our residual unfulfilled performance obligations are comprised primarily of long-term equipment rental arrangements in which we recognize revenues equal to what we have a right to invoice. Generally, no variable consideration exists related to our remaining performance obligations and no consideration is excluded from the associated transaction prices. However, the decrease in the current year deferred revenue balance is partially attributable to revenue recognized as variable consideration from shortfall penalties assessed to multiple customers according to contract terms as of December 31, 2019. During 2019, the Company recognized revenue as variable consideration from shortfall penalties according to contract terms in the amount of $70.6 million. In some cases, amounts recorded are estimates which are in negotiation and may increase or decrease.

Foreign Operations

Foreign operations constituted approximately $92.8 million and $66.9 million of our consolidated sales; $27.7 million and $7.3 million of consolidated assets; $7.0 million and $5.9 million of pre-tax income and $5.5 million and $4.7 million of net income as of and for the years ended December 31, 2019 and 2018, respectively. We had no significant foreign operations during the year ended December 31, 2017.

Asset Retirement Obligations

12 Months Ended

Dec. 31, 2019

Asset Retirement Obligation Disclosure [Abstract]

ASSET RETIREMENT OBLIGATIONS

NOTE M—ASSET RETIREMENT OBLIGATIONS

Mine reclamation or future remediation costs for inactive mines are accrued based on management’s best estimate at the end of each period of the costs expected to be incurred at a site. Such cost estimates include, where applicable, ongoing care, maintenance and monitoring costs. Changes in estimates at inactive mines are reflected in earnings in the period an estimate is revised.

As of December 31, 2019 and 2018, we had a liability of $25.8 million and $18.4 million, respectively, in other long-term obligations related to our asset retirement obligations. Changes in the asset retirement obligations (in thousands) during the years ended December 31, 2019 and 2018 are as follows:



	December 31, 2019		December 31, 2018
Beginning balance	$	18,413	$	19,032
Accretion	1,531		1,214
Additions and revisions of prior estimates	5,881		(319		)
Addition related to EPMH acquisition	—		2,733
EPMH measurement period adjustment	—		(2,131		)
Disposal related to sale of transloads	—		(2,116		)
Ending balance	$	25,825	$	18,413

The increase in liability is primarily attributable to additions due to increased environmental and acreage disturbance at certain plant sites and revisions of estimates of closure dates of certain plants sites.

Fair Value Accounting	12 Months Ended
Fair Value Accounting	Dec. 31, 2019
Fair Value Disclosures [Abstract]
FAIR VALUE ACCOUNTING	NOTE N—FAIR VALUE ACCOUNTING Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Fair value is estimated by applying the following hierarchy, which prioritizes the inputs used to measure fair value into three levels and bases the categorization within the hierarchy upon the lowest level of input that is available and significant to the fair value measurement: Level 1—Quoted prices in active markets for identical assets or liabilities. Level 2—Observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3—Inputs that are generally unobservable and typically reflect management’s estimate of assumptions that market participants would use in pricing the asset or liability. Cash Equivalents Due to the short-term maturity, we believe our cash equivalent instruments at December 31, 2019 and 2018, approximate their reported carrying values. Long-Term Debt, Including Current Maturities We believe that the fair values of our long-term debt, including current maturities, approximate their carrying values based on their effective interest rates compared to current market rates. Changes in the fair value of the royalty note payable utilize Level 3 inputs, such as estimates of future tonnages sold and average sales price. See Note K - Debt for more information on the change in fair value during the year ended December 31, 2019. Derivative Instruments The estimated fair value of our derivative instruments are recorded at each reporting period and are based upon widely accepted valuation techniques, including discounted cash flow analysis on the expected cash flows of each derivative contract. This analysis reflects the contractual terms of the derivatives, including the period to maturity, and uses observable market-based inputs, including interest rate curves and implied volatilities. We also incorporate credit valuation adjustments to appropriately reflect both our nonperformance risk as well as that of the respective counterparty in the fair value measurements. Although we have determined that the majority of the inputs used to value our derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with our derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default of ourselves and our counterparties. However, as of December 31, 2019, we have assessed that the impact of the credit valuation adjustments on the overall valuation of our derivative positions is not significant. As a result, we have determined that our derivative valuations in their entirety are classified in Level 2 of the fair value hierarchy. See Note O - Derivative Instruments for more information.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Derivative Instruments

12 Months Ended

Dec. 31, 2019

Derivative Instruments and Hedging Activities Disclosure [Abstract]

DERIVATIVE INSTRUMENTS

NOTE O—DERIVATIVE INSTRUMENTS

Cash Flow Hedges of Interest Rate Risk

We enter into interest rate swap agreements in connection with our Term Loan facility to add stability to interest expense and to manage our exposure to interest rate movements. The derivative instruments are recorded on the balance sheet within other current or long-term assets or liabilities based on maturity dates at their fair values. As of December 31, 2019, the fair value of our interest rate swaps was a liability of $2.8 million and a liability of $1.3 million which are classified within accounts payable and accrued liabilities on our balance sheet. Our interest rate cap matured on June 30, 2019. At December 31, 2018, the fair value of our two interest rate swaps was a liability of $1.5 million and a liability of $0.7 million and were classified within other long-term liabilities on our balance sheet. The fair value of our interest rate cap was zero. We have designated the interest rate swap agreements as qualified cash flow hedges. Accordingly, the effective portion of the gain or loss on the derivative instrument is reported as a component of other comprehensive income and recognized in earnings in the same period or periods during which the hedged transaction affects earnings.

The following table summarizes the fair value of our derivative instruments (in thousands, except contract/notional amount). See Note N - Fair Value Accounting for more information regarding the estimated fair values of our derivative instruments at December 31, 2019 and 2018.



	December 31, 2019										December 31, 2018
	Maturity Date	Contract/Notional Amount			Carrying Amount			Fair Value			Maturity Date	Contract/Notional Amount			Carrying Amount			Fair Value
LIBOR⁽¹⁾ interest rate swap agreement	2020		$440	million	$	(2,768	)	$	(2,768	)	2020		$440	million	$	(1,475	)	$	(1,475	)
LIBOR⁽¹⁾interest rate swap agreement	2020		$200	million	$	(1,259	)	$	(1,259	)	2020		$200	million	$	(663	)	$	(663	)
LIBORinterest rate cap agreement		$	—		$	—		$	—		2019		$249	million	$	—		$	—

⁽¹⁾ Agreements fix the LIBOR interest rate base to 2.74%

On May 1, 2018, as a result of entering into the new Credit Agreement, we determined the existing interest rate cap derivative no longer qualified for hedge accounting. During the year ended December 31, 2018 we recognized $76 thousand of deferred losses in accumulated other comprehensive loss into earnings.

During the year ended December 31, 2019, we had no ineffectiveness for the interest rate swap derivatives.

The following table summarizes the effect of derivative instruments (in thousands) on our income statements and our consolidated statements of comprehensive income for the years ended December 31, 2019, 2018 and 2017:



	2019			2018			2017
Deferred losses from derivatives in OCI, beginning of period	$	(1,621	)	$	(76	)	$	(32	)
(Loss) gain recognized in OCI from derivative instruments	(1,432		)	(1,622		)	(45		)
Loss reclassified from Accumulated OCI	—			77			1
Deferred losses from derivatives in OCI, end of period	$	(3,053	)	$	(1,621	)	$	(76	)

Equity-Based Compensation

12 Months Ended

Dec. 31, 2019

Share-based Payment Arrangement [Abstract]

EQUITY-BASED COMPENSATION

NOTE P—EQUITY-BASED COMPENSATION

In July 2011, we adopted the U.S. Silica Holdings, Inc. 2011 Incentive Compensation Plan (the “2011 Plan”), which was amended and restated in May 2015. The 2011 Plan provides for grants of stock options, restricted stock, performance share units and other incentive-based awards. We believe our 2011 Plan aligns the interests of our employees and directors with those of our common stockholders. At December 31, 2019, we have 1,769,759 shares of common stock that may be issued under the 2011 Plan. We use a combination of treasury stock and new shares if necessary to satisfy option exercises or vesting of restricted awards and performance share units.

Stock Options

The following table summarizes the status of, and changes in, our stock option awards during the year ended December 31, 2019:



	Number of Shares		Weighted Average Exercise Price		Aggregate Intrinsic Value		Weighted Average Remaining Contractual Term in Years
Outstanding at December 31, 2018	901,996		$	28.52	$	18,566	4.8 years
Granted	—		—		—
Exercised	(10,000	)	12.87		—
Forfeited	—		—		—
Expired	(65,338	)	$	25.16	$	—
Outstanding at December 31, 2019	826,658		$	28.97	$	—	4.1 years
Exercisable at December 31, 2019	826,658		$	28.97	$	11,557	4.1 years

There were no grants of stock options during the years ended December 31, 2019, 2018 and 2017.

There were 10,000, 4,167 and 43,774 stock options exercised during the years ended December 31, 2019, 2018 and 2017, respectively. The total intrinsic value of stock options exercised was $12 thousand, $0.1 million and $1.2 million for the years ended December 31, 2019, 2018 and 2017, respectively. Cash received from stock options exercised during the years ended December 31, 2019, 2018 and 2017 was $0.1 million, $0.1 million and $0.8 million, respectively. The tax benefit realized from stock option exercises was $3 thousand, $14 thousand and $0.4 million for the year ended December 31, 2019, 2018 and 2017, respectively.

As of December 31, 2019, there was no unrecognized compensation expense related to these options. We recognized $1.4 million and $2.5 million of equity-based compensation expense related to options during the years ended December 31, 2018 and 2017, respectively. We account for forfeitures as they occur.

Restricted Stock and Restricted Stock Unit Awards

The following table summarizes the status of, and changes in, our unvested restricted stock awards during the year ended December 31, 2019:



	Number of Shares		Grant Date Weighted Average Fair Value
Unvested, December 31, 2018	587,577		$	25.18
Granted	814,387		13.42
Vested	(306,806	)	26.18
Forfeited	(74,910	)	20.09
Unvested, December 31, 2019	1,020,248		$	15.86

We granted 814,387, 415,110 and 156,164 restricted stock and restricted stock unit awards during the years ended December 31, 2019, 2018 and 2017, respectively. The fair value of the awards was based on the market price of our stock at date of grant.

We recognized $8.2 million, $7.6 million and $7.1 million of equity-based compensation expense related to restricted stock awards during the years ended December 31, 2019, 2018 and 2017, respectively. As of December 31, 2019, there was $10.5 million of unrecognized compensation expense related to these restricted stock awards, which is expected to be recognized over a weighted-average period of 1.8 years.

Performance Share Unit Awards

The following table summarizes the status of, and changes in, our performance share unit awards during the year ended December 31, 2019:



	Number of Shares		Grant Date Weighted Average Fair Value
Unvested, December 31, 2018	838,188		$	39.44
Granted	607,130		15.58
Vested	(523,368	)	37.83
Forfeited/Cancelled	(83,228	)	25.60
Unvested, December 31, 2019	838,722		$	18.00

We granted 607,130, 261,500 and 90,501 of performance share unit awards during the years ended December 31, 2019, 2018 and 2017, respectively. The grant date weighted average fair value of these awards was estimated to be $15.58, $31.24 and $67.69 for the years ended December 31, 2019, 2018 and 2017, respectively, and the number of units that will vest will depend on the percentage ranking of the Company's total shareholder return ("TSR") compared to the TSR for each of the companies in the peer group over the three year period from January 1, 2019 through December 31, 2021 for the 2019 grant, January 1, 2018 through December 31, 2020 for the 2018 grant, and from January 1, 2017 through December 31, 2019 for the 2017 grant. The related compensation expense is recognized on a straight-line basis over the vesting period.

The grant date fair value for these awards was estimated using a Monte Carlo simulation model. The Monte Carlo simulation model requires the use of highly subjective assumptions. Our key assumptions in the model included the price and the expected volatility of our common stock and our self-determined peer group companies’ stock, risk-free rate of interest, dividend yields and cross-correlations between our common stock and our self-determined peer group companies' stock.

We recognized $7.7 million, $13.3 million and $15.5 million of compensation expense related to performance share unit awards during the years ended December 31, 2019, 2018 and 2017, respectively. As of December 31, 2019, there was $7.4 million of unrecognized compensation expense related to these performance share unit awards, which is expected to be recognized over a weighted-average period of 1.7 years.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2019

Commitments and Contingencies Disclosure [Abstract]

COMMITMENTS AND CONTINGENCIES

NOTE Q—COMMITMENTS AND CONTINGENCIES

Future Minimum Annual Commitments at December 31, 2019 (in thousands):



Year ending December 31,	Minimum Purchase Commitments
2020	$	14,512
2021	9,253
2022	6,900
2023	6,900
2024	3,593
Thereafter	2,490
Total future purchase commitments	$	43,648

Minimum Purchase Commitments

We enter into service agreements with our transload and transportation service providers. Some of these agreements require us to purchase a minimum amount of services over a specific period of time. Any inability to meet these minimum contract requirements requires us to pay a shortfall fee, which is based on the difference between the minimum amount contracted for and the actual amount purchased.

Contingent Liability on Royalty Agreement

On May 17, 2017, we purchased reserves in Crane County, Texas, for $94.4 million cash consideration plus contingent consideration. The contingent consideration is a royalty that is based on the tonnage shipped to third-parties. Because the contingent consideration is dependent on future tonnage sold, the amounts of which are uncertain, it is not currently possible to estimate the fair value of these future payments. The contingent consideration will be capitalized at the time a payment is probable and reasonably estimable, and the related depletion expense will be adjusted prospectively.

Other Commitments and Contingencies

Our operating subsidiary, U.S. Silica Company (“U.S. Silica”), has been named as a defendant in various product liability claims alleging silica exposure causing silicosis. During the year ended December 31, 2019, 2018 and 2017, one, twenty and zero claims, respectively, were brought against U.S. Silica. As of December 31, 2019, there were 58 active silica-related products liability claims pending in which U.S. Silica is a defendant. Although the outcomes of these claims cannot be predicted with certainty, in the opinion of management, it is not reasonably possible that the ultimate resolution of these matters will have a material adverse effect on our financial position or results of operations that exceeds the accrual amounts.

We have recorded estimated liabilities for these claims in other long-term obligations as well as estimated recoveries under the indemnity agreement and an estimate of future recoveries under insurance in other assets on our consolidated balance sheets. As of both December 31, 2019 and 2018, other non-current assets included zero for insurance for third-party products liability claims and other long-term obligations included $0.9 million and $0.9 million, respectively, for third-party products liability claims.

One of our subsidiaries has also been named as a defendant in lawsuits regarding certain labor practices. If we are unsuccessful in defending the litigation, these cases could result in a material liability for us.

Obligations Under Guarantees

We have indemnified our insurers against any loss they may incur in the event that holders of surety bonds, issued on our behalf, execute the bonds. As of December 31, 2019, there were $42.6 million in bonds outstanding. The majority of these bonds, $30.9 million relate to reclamation requirements issued by various government authorities. Reclamation bonds remain outstanding until the mining area is reclaimed and the authority issues a formal release. The remaining bonds relate to licenses, permits, and tax collections.

Pension and Post-Retirement Benefits

12 Months Ended

Dec. 31, 2019

Retirement Benefits [Abstract]

PENSION AND POST-RETIREMENT BENEFITS

NOTE R— PENSION AND POST-RETIREMENT BENEFITS

We maintain single-employer noncontributory defined benefit pension plans covering certain employees. There have been no new entrants to the U. S. Silica Company plan since May 2009 and to the EP Management Corporation plan since January 2007 for salaried participants and January 2010 for hourly participants when the plans were frozen to all new employees. The plans provide benefits based on each covered employee’s years of qualifying service. Our funding policy is to contribute amounts within the range of the minimum required and maximum deductible contributions for the plans consistent with a goal of appropriate minimization of the unfunded projected benefit obligations. The pension plans use a benefit level per year of service for covered hourly employees and a final average pay method for covered salaried employees. The plans use the projected unit credit cost method to determine the actuarial valuation.

We employ a total rate of return investment approach whereby a mix of equities and fixed income investments are used to maximize the long-term return of plan assets for a prudent level of risk. Risk tolerance is established through careful consideration of plan liabilities, plan funded status, and corporate financial condition. The investment portfolio contains a diversified blend of equity and fixed-income investments. Furthermore, equity investments are diversified across U.S. and non-U.S. stocks, as well as growth, value and small and large capitalizations. Investment risk is measured and monitored on an ongoing basis through quarterly investment portfolio reviews, annual liability measurements, and periodic asset/liability studies.

We employ a building block approach in determining the long-term rate of return for plan assets. Historical markets are studied and long-term historical relationships between equities and fixed-income are preserved consistent with the widely accepted capital market principle that assets with higher volatility generate a greater return over the long run. Current market factors such as inflation and interest rates are evaluated before long-term capital market assumptions are determined. The long-term portfolio return is established via a building block approach with proper consideration of diversification and rebalancing. Peer data and historical returns are reviewed to check for reasonability and appropriateness.

In addition, we provide defined benefit post-retirement health care and life insurance benefits to some employees. Covered employees become eligible for these benefits at retirement after meeting minimum age and service requirements. The projected future cost of providing post-retirement benefits, such as healthcare and life insurance, is recognized as an expense as employees render services. We previously maintained a Voluntary Employees’ Beneficiary Association trust that was used to partially fund health care benefits for future retirees. Benefits were funded to the extent contributions were tax deductible, which under current legislation is limited. In 2017, the trust terminated upon depletion of its assets, which were used in accordance with trust terms. In general, retiree health benefits are paid as covered expenses are incurred.

Net pension benefit cost (in thousands) consisted of the following for the years ended December 31, 2019, 2018 and 2017:



	Year Ended December 31,
	2019			2018			2017
Service cost	$	1,304		$	1,307		$	1,037
Interest cost	5,375			4,632			3,971
Expected return on plan assets	(6,171		)	(5,969		)	(5,265		)
Net amortization and deferral	1,648			2,526			1,773
Net pension benefit costs	$	2,156		$	2,496		$	1,516

Net post-retirement benefit cost (in thousands) consisted of the following for the years ended December 31, 2019, 2018 and 2017:



	Year Ended December 31,
	2019			2018		2017
Service cost	$	88		$	102	$	107
Interest cost	789			740		753
Expected return on plan assets	—			—		(1		)
Unrecognized net (gain)/loss	(29		)	—		—
Net post-retirement benefit costs	$	848		$	842	$	859

The changes in benefit obligations and plan assets (in thousands), as well as the funded status (in thousands) of our pension and post-retirement plans at December 31, 2019 and 2018 are as follows:



	Pension Benefits						Post-retirement Benefits
	2019			2018			2019			2018
Benefit obligation at January 1,	$	138,900		$	122,052		$	21,570		$	22,771
Service cost	1,304			1,307			88			102
Interest cost	5,375			4,632			789			740
Actuarial (gain) loss	17,225			(10,263		)	206			(965		)
Benefits paid	(14,922		)	(8,202		)	(815		)	(1,499		)
Other⁽¹⁾	609			29,374			216			421
Benefit obligation at December 31,	$	148,491		$	138,900		$	22,054		$	21,570
Fair value of plan assets at January 1,	$	102,396		$	92,067		$	—		$	—
Actual return on plan assets	17,919			(6,204		)	—			—
Employer contributions	4,755			3,350			599			1,078
Benefits paid	(14,922		)	(8,202		)	(815		)	(1,499		)
Other⁽¹⁾	283			21,385			216			421
Fair value of plan assets at December 31,	$	110,431		$	102,396		$	—		$	—
Plan assets less than benefit obligations at December 31 recognized as liability for pension and other post-retirement benefits	$	(38,060	)	$	(36,504	)	$	(22,054	)	$	(21,570	)



(1	)	Includes opening pension benefit obligation and plan assets balances related to the May 1, 2018, EPMH acquisition and other adjustments.

The accumulated benefit obligation for the defined benefit pension plans, which excludes the assumption of future salary increases, totaled $148.5 million and $138.9 million at December 31, 2019 and 2018, respectively.

We also sponsor unfunded, nonqualified pension plans. The projected benefit obligation, accumulated benefit obligation and fair value of plan assets for these plans were $1.6 million, $1.6 million and zero, respectively, at December 31, 2019 and $1.5 million, $1.5 million and zero. respectively, at December 31, 2018.

Future estimated annual benefit payments (in thousands) for pension and post-retirement benefit obligations at December 31, 2019 are as follows:



	Benefits
			Post-retirement
	Pension		Before Medicare Subsidy		After Medicare Subsidy
2020	$	10,025	$	1,601	$	1,431
2021	9,221		1,669		1,502
2022	9,195		1,686		1,520
2023	9,208		1,659		1,492
2024	9,551		1,677		1,513
2025-2029	45,386		7,526		6,677

Our best estimate of expected contributions to the pension and post-retirement medical benefit plans for the 2020 fiscal year are $5.1 million and $1.4 million, respectively.

The amounts in accumulated other comprehensive income (loss) expected to be recognized as components of net periodic benefit cost (in thousands) during the following fiscal year are as follows:



	Benefits
	Pension		Post-retirement		Total
Net actuarial loss	$	2,532	$	—	$	2,532
Prior service cost	534		—		534
	$	3,066	$	—	$	3,066

The total amounts in accumulated other comprehensive income (loss) related to net actuarial loss, net of tax, for the pension and post-retirement plans was $22.1 million and $17.6 million as of December 31, 2019 and 2018, respectively. The total amounts in accumulated other comprehensive income (loss) related to prior service cost, net of tax, for the pension and post-retirement plans, was $2.2 million and $2.8 million as of December 31, 2019 and 2018, respectively.

The following weighted-average assumptions were used to determine our obligations under the plans:



	Pension Benefits				Post-retirement Benefits
	2019		2018		2019		2018
Discount rate	3.2	%	4.4	%	3.2	%	4.3	%
Long-term rate of compensation increase	3.0%-3.5%		3.0%-3.5%		N/A		N/A
Long-term rate of return on plan assets	6.3	%	6.25%-7.15%		N/A		N/A
Health care cost trend rate:
Pre-65 initial rate/ultimate rate	N/A		N/A		7.0%/4.5%		7.3%/4.5%
Pre-65 ultimate year	N/A		N/A		—		—
Post-65 initial rate/ultimate rate	N/A		N/A		7.5%/4.5%		8.0%/4.5%
Post-65 ultimate year	N/A		N/A		2026/2027		2026/2027

The weighted average discount rate used to determine the projected pension and post-retirement obligations was updated to 3.2% at December 31, 2019 from 4.4% at December 31, 2018. The discount rate reflects the expected long-term rates of return with maturities comparable to payments for the plan obligations utilizing Aon Hewitt's AA Above Medium Curve.

Mortality tables used for pension benefits and post-retirement benefits plans are the following:



	Pension and Post-retirement Benefits
	2019	2018
Healthy Lives	Pri-2012 base mortality tables with generational mortality improvements using Scale MP-2019	RP-2014 mortality table, adjusted back to 2006 base rates, with generational mortality improvements using Scale MP-2018
Disabled Lives	Pri-2012 base mortality tables with generational mortality improvements using Scale MP-2019	RP-2014 disabled retiree mortality table, adjusted back to 2006 base rates, with generational mortality improvements using Scale MP-2018

Assumed health care cost trend rates have a significant effect on the amounts reported for the health care plans. A one-percentage-point change in assumed health care cost trend rates would have the following effects (in thousands):



	One-Percentage-Point
	Increase		Decrease
Effect on total of service and interest cost	$	100	$	(85	)
Effect on post-retirement benefit obligation	2,341		(2,010		)

The major investment categories and their relative percentage of the fair value of total plan assets as invested at December 31, 2019, and 2018 are as follows:



	Pension Benefits				Post-retirement Benefits⁽¹⁾
	2019		2018		2019		2018
Equity securities	52.1	%	42.1	%	—	%	—	%
Debt securities	46.6	%	55.5	%	—	%	—	%
Cash	1.3	%	2.4	%	—	%	—	%



(1	)	Retiree health benefits are paid by the Company as covered expenses are incurred.

The fair values of the pension plan assets (in thousands) at December 31, 2019, by asset category, are as follows:



	Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	—	$	1,385	$	—	$	1,385
Mutual funds:
Diversified emerging markets	4,942		—		—		4,942
Foreign large blend	19,183		—		—		19,183
Large-cap blend	20,738		—		—		20,738
Mid-cap blend	8,416		—		—		8,416
Real estate	4,309		—		—		4,309
Fixed income securities:
Corporate notes and bonds	37,664		—		—		37,664
U.S. Treasuries	10,894		—		—		10,894
Mortgage-backed securities	—		2,496		—		2,496
Asset-backed securities	—		404		—		404
Net asset	$	106,146	$	4,285	$	—	$	110,431

The fair values of the pension plan assets (in thousands) at December 31, 2018, by asset category, are as follows:



	Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	—	$	2,449	$	—	$	2,449
Mutual funds:
Diversified emerging markets	6,638		—		—		6,638
Foreign large blend	11,689		—		—		11,689
Large-cap blend	14,226		—		—		14,226
Mid-cap blend	6,819		—		—		6,819
Small-cap blend	522		—		—		522
Real estate	3,192		—		—		3,192
Fixed income securities:
Corporate notes and bonds	43,745		—		—		43,745
U.S. Treasuries	8,486		—		—		8,486
Mortgage-backed securities	—		3,578		—		3,578
Asset-backed securities	—		1,052		—		1,052
Net asset	$	95,317	$	7,079	$	—	$	102,396

We contribute to three multiemployer defined benefit pension plans under the terms of collective-bargaining agreements for union-represented employees. A multiemployer plan is subject to collective bargaining for employees of two or more unrelated companies. These plans allow multiple employers to pool their pension resources and realize efficiencies associated with the daily administration of the plan. Multiemployer plans are generally governed by a board of trustees composed of management and labor representatives and are funded through employer contributions. However, in most cases, management is not directly represented.

The risks of participating in multiemployer plans differ from single employer plans as follows: 1) assets contributed to a multiemployer plan by one employer may be used to provide benefits to employees of other participating employers, 2) if a participating employer stops contributing to the plan, the unfunded obligations of the plan may be borne by the remaining participating employers, and 3) if we cease to have an obligation to contribute to one or more of the multiemployer plans to which we contribute, we may be required to pay those plans an amount based on the underfunded status of the plan, referred to as a withdrawal liability.

A summary of each multiemployer pension plan for which we participate is presented below:

Pension

Fund

EIN/ Pension

Plan No.

Pension Protection Act

Zone Status⁽¹⁾

FIP/RP Status

Pending/

Implemented

Company

Contributions

(in thousands)

Surcharge

Imposed

Expiration

Date of

CBA

2019

2018

2019

2018

2017

LIUNA

52-6074345/001

Red

Yes

385

573

223

Yes

5/31/2020

IUOE

36-6052390/001

Green

310

1,385

7/31/2022

CSSS⁽²⁾

36-6044243/001

Red

Yes


(1)	The Pension Protection Act of 2006 defines the zone status as follows: green—healthy, yellow—endangered, orange—seriously endangered and red—critical.


(2)	In 2011, we withdrew from the Central States, Southeast and Southwest Areas Pension Plan. The withdrawal liability of $1.0 million will be paid in monthly installments of $4,000 until 2031.

Our contributions to individual multiemployer pension funds did not exceed 5% of the fund’s total contributions for the years ended December 31, 2019, 2018 and 2017. Additionally, our contributions to multiemployer post-retirement benefit plans were immaterial for all periods presented in the accompanying consolidated financial statements.

We also sponsor a defined contribution plan covering certain employees. We contribute to the plan in two ways. For certain employees not covered by the defined benefit plan, we make a contribution equal to 4% of their salary. We may also contribute an employee discretionary match of up to 50 cents for each dollar contributed by an employee, up to 4% of their earnings. Finally, for some employees, we make a catch-up match of one dollar for each dollar contributed by an employee, up to 6% of catch-up contributions. Contributions were $6.1 million, $2.6 million and $3.0 million for the years ended December 31, 2019, 2018 and 2017, respectively.

Leases

12 Months Ended

Dec. 31, 2019

Leases [Abstract]

Leases

NOTE S— LEASES

We lease railroad cars, office space, mining property, mining/processing equipment, and transportation and other equipment. The majority of our leases have remaining lease terms of one year to 20 years. Our lease terms may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. We have lease agreements with lease and non-lease components, the latter of which are generally accounted for separately.

Supplemental balance sheet information related to leases (in thousands except for term and rate information) was as follows:



Leases	Classification	December 31, 2019
Assets
Operating	Operating lease right-of-use assets	$	53,098
Total leased assets		$	53,098
Liabilities
Current
Operating	Current portion of operating lease liabilities	$	53,587
Non-Current
Operating	Operating lease liabilities	117,964
Total lease liabilities		$	171,551

We recorded impairment charges of approximately $115.4 million related to the write down of value in the sand railcar fleet to their estimated fair value. These charges relate mainly to the Oil & Gas Segment and are recorded in "Goodwill and other asset impairments" in the Consolidated Statements of Operations. See Note Z - Impairments for additional information.

Operating lease liabilities are based on the net present value of the remaining lease payments over the remaining lease term. As most of our leases do not provide an implicit rate, in determining the lease liability and the present value of lease payments, we used our incremental borrowing rate based on the information available at the lease commencement date. The weighted average remaining lease term and discount rate as of December 31, 2019 related to leases are as follows:



Lease Term and Discount Rate
Weighted average remaining lease term (years):
Operating leases	4.5 years

Weighted average discount rate:
Operating leases	5.7	%

The components of lease expense included in our Consolidated Statements of Operations were as follows:



Lease Costs	Classification	Year Ended December 31, 2019
Operating lease costs (1)	Cost of Sales	$	88,966
Operating lease costs (2)	Selling, general, and administrative	3,993
Right-of-use asset impairment	Goodwill and other asset impairments	115,443
Total		$	208,402

(1) Includes short-term operating lease costs of $18.2 million for the year ended December 31, 2019.

(2) Includes short-term operating lease costs of $0.7 million for the year ended December 31, 2019.

Supplemental cash flow information related to leases was as follows:



	Year Ended December 31, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows for operating leases	$	74,740

Right-of-use assets obtained in exchange for new lease liabilities:
Operating leases	$	232,123

Maturities of lease liabilities as of December 31, 2019:



Maturities of lease liabilities	Operating leases
2020	$	63,337
2021	44,276
2022	33,526
2023	22,380
2024	16,236
Thereafter	22,284
Total lease payments	$	202,039
Less: Interest	30,488
Total	$	171,551

Income Taxes

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

INCOME TAXES

NOTE T— INCOME TAXES

We evaluate our deferred tax assets periodically to determine if valuation allowances are required. Ultimately, the realization of deferred tax assets is dependent upon generation of future taxable income during those periods in which temporary differences become deductible and/or credits can be utilized. To this end, management considers the level of historical taxable income, the scheduled reversal of deferred tax liabilities, tax-planning strategies and projected future taxable income. Based on these considerations, and the carry-forward availability of a portion of the deferred tax assets, management believes it is more likely than not that we will realize the benefit of the deferred tax assets.

Income tax benefit (in thousands) consisted of the following for the years ended December 31, 2019, 2018 and 2017:



	Year ended December 31,
	2019			2018			2017
Current:
Federal	$	—		$	1,076		$	(10,754	)
State	(1,188		)	(2,496		)	(1,167		)
Foreign	(1,343		)	(518		)	—
	(2,531		)	(1,938		)	(11,921		)
Deferred:
Federal	90,457			25,578			22,641
State	11,225			5,492			(2,040		)
Foreign	—			—			—
	101,682			31,070			20,601
Income tax benefit	$	99,151		$	29,132		$	8,680

Income tax benefit (in thousands) differed from the amount that would be provided by applying the U.S. federal statutory rate for the years ended December 31, 2019, 2018 and 2017 due to the following:



	Year ended December 31,
	2019			2018			2017
Income tax (expense) benefit computed at U.S. federal statutory rate	$	90,070		$	48,290		$	(47,784	)
Decrease (increase) resulting from:
Statutory depletion	4,679			12,090			20,259
Goodwill impairment	—			(29,157		)	—
Prior year tax return reconciliation	3,121			530			219
State income taxes, net of federal benefit	9,486			2,592			(2,267		)
Adjustment to deferred taxes from the Tax Act rate reduction	—			—			35,772
Equity compensation	(6,440		)	(653		)	2,602
Other, net	(1,765		)	(4,560		)	(121		)
Income tax benefit	$	99,151		$	29,132		$	8,680

The largest permanent item in computing both our effective tax rate and taxable income is the deduction allowed for statutory percentage depletion. The deduction for statutory percentage depletion does not necessarily change proportionately to changes in income before income taxes. For the year ended December 31, 2018, the tax effect of the goodwill impairment described in Note I - Goodwill and Intangible Assets is a significant permanent item in the effective tax rate calculation.

Deferred tax assets and liabilities are recognized for the estimated future tax effects, based on enacted tax laws, of temporary differences between the values of assets and liabilities recorded for financial reporting and for tax purposes and of net operating loss and other carry forwards.

The tax effects of the types of temporary differences and carry forwards that gave rise to deferred tax assets and liabilities (in thousands) at December 31, 2019 and 2018 consisted of the following:



	December 31,
	2019			2018
Gross deferred tax assets:
Net operating loss carry forward and state tax credits	$	32,173		$	11,089
Pension and post-retirement benefit costs	13,976			13,303
Alternative minimum tax credit carry forward	7,895			15,971
Property, plant and equipment	7,179			5,474
Accrued expenses	15,336			27,025
Inventories	6,507			774
Third-party products liability	236			231
Stock-based compensation expense	2,390			8,199
Note payable	109			3,724
Interest expense limitation	22,324			—
Lease obligation liability	29,604			—
Other	5,191			8,116
Total deferred tax assets	142,920			93,906
Gross deferred tax liabilities:
Land and mineral property basis difference	(124,182		)	(165,002		)
Fixed assets and depreciation	(44,314		)	(55,596		)
Intangibles	(12,541		)	(10,346		)
Other	(468		)	(201		)
Total deferred tax liabilities	(181,505		)	(231,145		)
Net deferred tax liabilities	$	(38,585	)	$	(137,239	)

We have federal net operating loss carry forwards of approximately $122.3 million at December 31, 2019. The losses will expire in years 2028 through 2037. The losses are subject to an annual limitation under Internal Revenue Code Section 382, but are expected to be fully realized. Under the Tax Act, net operating loss (NOL) deductions arising in tax years beginning after December 31, 2017 can only offset up to 80 percent of future taxable income. The Act also prohibits NOL carrybacks, but allows indefinite carryforwards for NOLs arising in tax years beginning after December 31, 2017. Net operating losses arising before January 1, 2018 are accounted for under the previous tax rules that imposed no limit on the amount of the taxable income that can be set off using NOLs (except for a 90 percent limit for AMT carryforwards) and that can be carried back 2 years and carried forward 20 years.

At December 31, 2019 and 2018, we have an alternative minimum tax credit carry forward of approximately $16.2 million and $16.0 million, respectively. The Tax Act repeals the corporate alternative minimum tax (AMT), effective for tax years beginning after December 31, 2017, but allows an entity to claim portions of any unused AMT credits over the next four years to offset its regular tax liability. An entity with unused AMT credits as of December 31, 2017 can first use these credits to offset its regular tax for 2017 and can then claim up to 50 percent of the remaining AMT credits in 2018, 2019, and 2020, with all remaining AMT credits refundable in 2021. Based on the Tax Act repeal of AMT, $8.1 million was reclassified from deferred tax assets to other receivables. See Note F - Accounts Receivable.

At the end of each reporting period as presented, there were no material amounts of interest and penalties recognized in the statement of operations or balance sheets. We have no material unrecognized tax benefits or any known material tax contingencies at December 31, 2019 or December 31, 2018 and do not expect this to change significantly within the next twelve months. Tax returns filed with the IRS for the years 2016 through 2018 along with tax returns filed with numerous state entities remain subject to examination.

Revenue

12 Months Ended

Dec. 31, 2019

Revenue from Contract with Customer [Abstract]

REVENUE

NOTE L—DEFERRED REVENUE

which are in negotiation and may increase or decrease. We believe this is the best estimate of revenue to recognize as of December 31, 2019.

NOTE U— REVENUE



	Year Ended December 31, 2019						Year Ended December 31, 2018
Category	Oil & Gas Proppants		Industrial & Specialty Products		Total Sales		Oil & Gas Proppants		Industrial & Specialty Products		Total Sales
Product	$	704,516	$	463,956	$	1,168,472	$	888,509	$	394,290	$	1,282,799
Service	306,005		—		306,005		294,482		17		294,499
Total Sales	$	1,010,521	$	463,956	$	1,474,477	$	1,182,991	$	394,307	$	1,577,298



	Unbilled Receivables
	December 31, 2019			December 31, 2018
Beginning Balance	$	90		$	5,245
Reclassifications to billed receivables	(3,983		)	(11,157		)
Revenues recognized in excess of period billings	4,037			6,002
Ending Balance	$	144		$	90



	Deferred Revenue
	December 31, 2019			December 31, 2018
Beginning Balance	$	113,319		$	118,414
Revenues recognized from balances held at the beginning of the period	(65,225		)	(33,381		)
Revenues deferred from period collections on unfulfilled performance obligations	12,225			31,625
Revenues recognized from period collections	(9,685		)	(3,339		)
Ending Balance	$	50,634		$	113,319

Foreign Operations

Related Party Transactions	12 Months Ended
Related Party Transactions	Dec. 31, 2019
Related Party Transactions [Abstract]
RELATED PARTY TRANSACTIONS	NOTE V— RELATED PARTY TRANSACTIONS A former employee, who was an officer of one of our operating subsidiaries prior to the third quarter of 2018, held an ownership interest in a transportation brokerage and logistics services vendor, from which we made purchases of approximately $2.9 million and $4.7 million for the years ended December 31, 2018 and, 2017, respectively. There were no related party transactions during the year ended December 31, 2019.

Segment Reporting

12 Months Ended

Dec. 31, 2019

Segment Reporting [Abstract]

SEGMENT REPORTING

NOTE W— SEGMENT REPORTING

Our business is organized into two reportable segments, Oil & Gas Proppants and Industrial & Specialty Products, based on end markets. The reportable segments are consistent with how management views the markets that we serve and the financial information reviewed by the chief operating decision maker. We manage our Oil & Gas Proppants and Industrial & Specialty Products businesses as components of an enterprise for which separate information is available and is evaluated regularly by the chief operating decision maker in deciding how to allocate resources and assess performance.

In the Oil & Gas Proppants segment, we serve the oil and gas recovery market primarily by providing and delivering fracturing sand, or “frac sand,” which is pumped down oil and natural gas wells to prop open rock fissures and increase the flow rate of oil and natural gas from the wells.

The Industrial & Specialty Products segment consists of over 400 product types and materials used in a variety of markets including building and construction products, fillers and extenders, filtration, glassmaking, absorbents, foundry, and sports and recreation.

An operating segment’s performance is primarily evaluated based on segment contribution margin, which excludes selling, general, and administrative costs, corporate costs, plant capacity expansion expenses, and facility closure costs. We believe that segment contribution margin, as defined above, is an appropriate measure for evaluating the operating performance of our segments. However, segment contribution margin is a non-GAAP measure and should be considered in addition to, not a substitute for, or superior to, net income (loss) or other measures of financial performance prepared in accordance with GAAP. The other accounting policies of each of the two reportable segments are the same as those in Note B - Summary of Significant Accounting Policies to these Consolidated Financial Statements.

The following table presents sales and segment contribution margin (in thousands) for the reportable segments and other operating results not allocated to the reported segments for the years ended December 31, 2019, 2018 and 2017:



	Year Ended December 31,
	2019			2018			2017
Sales:
Oil & Gas Proppants	$	1,010,521		$	1,182,991		$	1,020,365
Industrial & Specialty Products	463,956			394,307			220,486
Total sales	1,474,477			1,577,298			1,240,851
Segment contribution margin:
Oil & Gas Proppants	248,594			357,846			301,972
Industrial & Specialty Products	178,215			155,084			88,781
Total segment contribution margin	426,809			512,930			390,753
Operating activities excluded from segment cost of sales⁽¹⁾	(85,625		)	(98,761		)	(16,722		)
Selling, general and administrative	(150,848		)	(146,971		)	(107,056		)
Depreciation, depletion and amortization	(179,444		)	(148,832		)	(97,233		)
Goodwill and other asset impairments	(363,847		)	(281,899		)	—
Interest expense	(95,472		)	(70,564		)	(31,342		)
Other income (expense), net, including interest income	19,519			4,144			(1,874		)
Income tax benefit	99,151			29,132			8,680
Net (loss) income	$	(329,757	)	$	(200,821	)	$	145,206
Less: Net loss attributable to non-controlling interest	(675		)	(13		)	—
Net (loss) income attributable to U.S. Silica Holdings, Inc.	$	(329,082	)	$	(200,808	)	$	145,206



(1)	2019 and 2018 mainly driven by plant capacity expansion expenses, amortization of purchase accounting inventory fair value step-up, and facility closure costs.

Asset information, including capital expenditures and depreciation, depletion, and amortization, by segment is not included in reports used by management in its monitoring of performance and, therefore, is not reported by segment. At December 31, 2019, goodwill of $273.5 million has been allocated to these segments with $86.1 million assigned to Oil & Gas Proppants and $187.4 million to Industrial & Specialty Products. At December 31, 2018, goodwill of $261.3 million had been allocated to these segments with $86.1 million assigned to Oil & Gas Proppants and $175.2 million to Industrial & Specialty Products.

Unaudited Supplementary Data

12 Months Ended

Dec. 31, 2019

Quarterly Financial Information Disclosure [Abstract]

UNAUDITED SUPPLEMENTARY DATA

NOTE X— UNAUDITED SUPPLEMENTARY DATA

The following table sets forth our unaudited quarterly consolidated statements of operations (in thousands, except per share data) for each of the four quarters in the years ended December 31, 2019 and 2018. This unaudited quarterly information has been prepared on the same basis as our annual audited financial statements and includes all adjustments, consisting only of normal recurring adjustments that are necessary to present fairly the financial information for the fiscal quarters presented.



	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
2019	(Unaudited)
Sales:
Product	$	296,860		$	303,041		$	287,977		$	280,594
Service	81,890			91,813			73,837			58,465
Cost of sales (excluding depreciation, depletion and amortization):
Product	234,916			225,473			226,797			212,905
Service	62,622			68,687			56,836			45,057
Operating expenses:
Selling, general and administrative	34,656			38,659			40,208			37,325
Depreciation, depletion and amortization	44,600			44,899			47,126			42,819
Goodwill and other asset impairments	—			—			130			363,717
Total operating expenses	79,256			83,558			87,464			443,861
Operating (loss) income	1,956			17,136			(9,283		)	(362,764		)
Other (expense) income:
Interest expense	(23,978		)	(23,765		)	(24,733		)	(22,996		)
Other income (expense), net, including interest income	722			15,074			3,280			443
Total other expense	(23,256		)	(8,691		)	(21,453		)	(22,553		)
(Loss) income before income taxes	(21,300		)	8,445			(30,736		)	(385,317		)
Income tax benefit	1,972			(2,384		)	7,671			91,892
Net (loss) income	(19,328		)	6,061			(23,065		)	(293,425		)
Less: Net loss attributable to non-controlling interest	(4		)	(89		)	(28		)	(554		)
Net (loss) income attributable to U.S. Silica Holdings, Inc.	$	(19,324	)	$	6,150		$	(23,037	)	$	(292,871	)

(Loss) earnings per share, basic	$	(0.26	)	$	0.08		$	(0.31	)	$	(4.00	)
(Loss) earnings per share, diluted	$	(0.26	)	$	0.08		$	(0.31	)	$	(4.00	)
Weighted average shares outstanding, basic	73,040			73,301			73,328			73,343
Weighted average shares outstanding, diluted	73,040			73,505			73,328			73,343
Dividends declared per share	$	0.06		$	0.06		$	0.06		$	0.06

	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
2018	(Unaudited)
Sales:
Product	$	294,788		$	345,957		$	348,635		$	293,419
Service	74,525			81,476			74,537			63,961



Cost of sales (excluding depreciation, depletion and amortization):
Product	207,239			236,236			270,370			241,624
Service	53,671			56,609			51,966			45,414
Operating expenses:
Selling, general and administrative	34,591			42,232			37,980			32,168
Depreciation, depletion and amortization	28,592			36,563			37,150			46,527
Goodwill and other asset impairments	—			16,184			—			265,715
Total operating expenses	63,183			94,979			75,130			344,410
Operating (loss) income	45,220			39,609			25,706			(274,068		)
Other (expense) income:
Interest expense	(7,070		)	(20,214		)	(21,999		)	(21,281		)
Other income (expense), net, including interest income	665			1,081			1,062			1,336
Total other expense	(6,405		)	(19,133		)	(20,937		)	(19,945		)
(Loss) income before income taxes	38,815			20,476			4,769			(294,013		)
Income tax benefit	(7,521		)	(2,832		)	1,547			37,938
Net (loss) income	31,294			17,644			6,316			(256,075		)
Less: Net loss attributable to non-controlling interest	—			—			—			(13		)
Net (loss) income attributable to U.S. Silica Holdings, Inc.	$	31,294		$	17,644		$	6,316		$	(256,062	)

Earnings (loss) per share, basic	$	0.39		$	0.23		$	0.08		$	(3.44	)
Earnings (loss) per share, diluted	$	0.39		$	0.22		$	0.08		$	(3.44	)
Weighted average shares, basic	79,496			77,784			77,365			74,485
Weighted average shares, diluted	80,309			78,480			77,859			74,485
Dividends declared per share	$	0.06		$	0.06		$	0.06		$	0.06

Parent Company Financials

12 Months Ended

Dec. 31, 2019

Condensed Financial Information Disclosure [Abstract]

PARENT COMPANY FINANCIALS

NOTE Y— PARENT COMPANY FINANCIALS

U.S. SILICA HOLDINGS, INC.

(PARENT COMPANY ONLY)

CONDENSED BALANCE SHEETS



	December 31,
	2019			2018
	(in thousands)
ASSETS
Current Assets:
Cash and cash equivalents	$	51,849		$	107,151
Due from affiliates	138,988			100,094
Total current assets	190,837			207,245
Investment in subsidiaries	530,830			850,099
Total assets	$	721,667		$	1,057,344
LIABILITIES AND STOCKHOLDERS’ EQUITY
Current Liabilities:
Accrued expenses and other current liabilities	$	129		$	217
Dividends payable	4,958			4,823
Total current liabilities	5,087			5,040
Total liabilities	5,087			5,040
Stockholders’ Equity:
Preferred stock	—			—
Common stock	823			818
Additional paid-in capital	1,185,116			1,169,383
Retained (deficit) earnings	(279,956		)	67,854
Treasury stock, at cost	(180,912		)	(178,215		)
Accumulated other comprehensive loss	(19,854		)	(15,020		)
Total U.S. Silica Holdings, Inc. stockholders’ equity	705,217			1,044,820
Non-controlling interest	11,363			7,484
Total stockholders' equity	716,580			1,052,304
Total liabilities and stockholders’ equity	$	721,667		$	1,057,344

U.S. SILICA HOLDINGS, INC.

(PARENT COMPANY ONLY)

CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS)



	Year ended December 31,
	2019			2018			2017
	(in thousands)
Sales	$	—		$	—		$	—
Cost of sales	—			—			—
Operating expenses
Selling, general and administrative	253			254			252
Total operating expenses	253			254			252
Operating loss	(253		)	(254		)	(252		)
Other income (expense)
Interest income	1,440			2,784			3,854
Total other income	1,440			2,784			3,854
Income before income taxes and equity in net earnings of subsidiaries	1,187			2,530			3,602
Income tax expense	(327		)	(696		)	(1,453		)
Income before equity in net earnings of subsidiaries	860			1,834			2,149
Equity in earnings of subsidiaries, net of tax	(330,617		)	(202,655		)	143,057
Net (loss) income	(329,757		)	(200,821		)	145,206
Less: Net loss attributable to non-controlling interest	(675		)	(13		)	—
Net (loss) income attributable to U.S. Silica Holdings, Inc.	(329,082		)	(200,808		)	145,206

Net (loss) income	(329,757		)	(200,821		)	145,206
Other comprehensive (loss) income
Unrealized loss on derivatives (net of tax of $(456),$(470), and $(27) for 2019, 2018, and 2017, respectively)	(1,432		)	(1,545		)	(44		)
Foreign currency translation adjustment (net of tax of $(60), $(196), and $2 for 2019, 2018 and 2017, respectively)	(188		)	(614		)	(6		)
Pension and other post-retirement benefits liability adjustment (net of tax of $(1,024), $339, and $1,205 for 2019, 2018 and 2017, respectively)	(3,214		)	1,065			2,000
Comprehensive (loss) income	(334,591		)	(201,915		)	147,156
Less: Comprehensive loss attributable to non-controlling interest	(675		)	(13		)	—
Comprehensive (loss) income attributable to U.S. Silica Holdings, Inc.	(333,916		)	(201,902		)	147,156

U.S. SILICA HOLDINGS, INC.

(PARENT COMPANY ONLY)

CONDENSED STATEMENTS OF STOCKHOLDERS' EQUITY



(amounts in thousands)	Par Value		Treasury Stock			Additional Paid-In Capital			Retained Earnings - Present			Accumulated Other Comprehensive Income (Loss)			Total U.S. Silica, Inc. Stockholders' Equity			Non-controlling Interest			Total Stockholders’ Equity
Balance at January 1, 2017	$	811	$	(3,869	)	$	1,129,051		$	163,173		$	(15,876	)	$	1,273,290		$	—		$	1,273,290
Net income	—		—			—			145,206			—			145,206			—			145,206
Unrealized loss on derivatives	—		—			—			—			(44		)	(44		)	—			(44		)
Foreign currency translation adjustment	—		—			—			—			(6		)	(6		)	—			(6		)
Pension and post-retirement liability	—		—			—			—			2,000			2,000			—			2,000
Cash dividend declared ($0.25 per share)	—		—			—			(20,387		)	—			(20,387		)	—			(20,387		)
Common stock-based compensation plans activity:
Equity-based compensation	—		—			25,050			—			—			25,050			—			25,050
Proceeds from options exercised	—		1,190			(392		)	—			—			798			—			798
Issuance of restricted stock	—		1,859			(1,859		)	—			—			—			—			—
Shares withheld for employee taxes related to vested restricted stock and stock units	1		386			(4,766		)	—			—			(4,379		)	—			(4,379		)
Repurchase of common stock			(25,022		)										(25,022		)	—			(25,022		)
Balance at December 31, 2017	$	812	$	(25,456	)	$	1,147,084		$	287,992		$	(13,926	)	$	1,396,506		$	—		$	1,396,506
Net loss	—		—			—			(200,808		)	—			(200,808		)	(13		)	(200,821		)
Unrealized loss on derivatives	—		—			—			—			(1,545		)	(1,545		)	—			(1,545		)
Foreign currency translation adjustment	—		—			—			—			(614		)	(614		)	—			(614		)
Pension and post-retirement liability	—		—			—			—			1,065			1,065			—			1,065
Cash dividend declared ($0.25 per share)	—		—			—			(19,330		)	—			(19,330		)	—			(19,330		)
Contributions from non-controlling interest	—		—			—			—			—			—			7,497			7,497
Common stock-based compensation plans activity:
Equity-based compensation	—		—			22,337			—			—			22,337			—			22,337
Proceeds from options exercised	—		93			(32		)	—			—			61			—			61
Shares withheld for employee taxes related to vested restricted stock and stock units	6		(4,383		)	(6		)	—			—			(4,383		)	—			(4,383		)
Repurchase of common stock	—		(148,469		)	—			—			—			(148,469		)	—			(148,469		)
Balance at December 31, 2018	$	818	$	(178,215	)	$	1,169,383		$	67,854		$	(15,020	)	$	1,044,820		$	7,484		$	1,052,304
Net loss	—		—			—			(329,082		)	—			(329,082		)	(675		)	(329,757		)
Unrealized loss on derivatives	—		—			—			—			(1,432		)	(1,432		)	—			(1,432		)
Foreign currency translation adjustment	—		—			—			—			(188		)	(188		)	—			(188		)
Pension and post-retirement liability	—		—			—			—			(3,214		)	(3,214		)	—			(3,214		)
Cash dividend declared ($0.25 per share)	—		—			—			(18,728		)	—			(18,728		)	—			(18,728		)
Contributions from non-controlling interest	—		—			—			—			—			—			4,554			4,554
Common stock-based compensation plans activity:



Equity-based compensation	—		—			15,906			—			—			15,906			—		15,906
Proceeds from options exercised	—		296			(168		)	—			—			128			—		128
Shares withheld for employee taxes related to vested restricted stock and stock units	5		(2,993		)	(5		)	—			—			(2,993		)	—		(2,993		)
Balance at December 31, 2019	$	823	$	(180,912	)	$	1,185,116		$	(279,956	)	$	(19,854	)	$	705,217		$	11,363	$	716,580

U.S. SILICA HOLDINGS, INC.

(PARENT COMPANY ONLY)

CONDENSED STATEMENTS OF CASH FLOWS



	Year ended December 31,
	2019			2018			2017
	(in thousands)
Operating activities:
Net (loss) income	$	(329,757	)	$	(200,821	)	$	145,206
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Undistributed loss (income) from equity method investment, net	330,617			202,655			(143,057		)
Changes in assets and liabilities, net of effects of acquisitions:
Accounts payable and accrued liabilities	(88		)	(295		)	48
Net cash provided by operating activities	772			1,539			2,197
Investing activities:
Investment in subsidiary	—			—			(143,654		)
Net cash used in investing activities	—			—			(143,654		)
Financing activities:
Dividends paid	(18,592		)	(19,912		)	(20,377		)
Repurchase of common stock	—			(148,469		)	(25,022		)
Proceeds from options exercised	128			61			798
Tax payments related to shares withheld for vested restricted stock and stock units	(2,993		)	(4,383		)	(4,379		)
Contributions from non-controlling interest	4,554			7,497			—
Net financing activities with subsidiaries	(39,171		)	40,171			(113,294		)
Net cash used in financing activities	(56,074		)	(125,035		)	(162,274		)
Net decrease in cash and cash equivalents	(55,302		)	(123,496		)	(303,731		)
Cash and cash equivalents, beginning of period	107,151			230,647			534,378
Cash and cash equivalents, end of period	$	51,849		$	107,151		$	230,647
Supplemental cash flow information:
Cash (received) paid during the period for:
Interest	$	(1,440	)	$	(2,784	)	$	(3,853	)

Notes to Condensed Financial Statements of Registrant (Parent Company Only)

These condensed parent company only financial statements have been prepared in accordance with Rule 12-04, Schedule I of Regulation S-X, because the restricted net assets of the subsidiaries of U.S. Silica Holdings, Inc. (as defined in Rule 4-08(e)(3) of Regulation S-X) exceed 25% of the consolidated net assets of the Company. The ability of the Company's operating subsidiaries to pay dividends may be restricted due to the terms of the Company's Credit Facility, as discussed in Note K - Debt to these financial statements.

These condensed parent company financial statements have been prepared using the same accounting principles and policies described in the notes to the consolidated financial statements; the only exceptions are that (a) the parent company accounts for its subsidiaries using the equity method of accounting, (b) taxes are allocated to the parent from the subsidiary using the separate return method, and (c) intercompany loans are not eliminated. In the parent company financial statements, the Company's investment in subsidiaries is stated at cost plus equity in undistributed earnings of subsidiaries since the date of acquisition. These condensed parent company financial statements should be read in conjunction with the Company's consolidated financial statements and related notes thereto included elsewhere in this report.

No cash dividends were paid to the parent by its consolidated entities for the years presented in the condensed financial statements.

Impairments

12 Months Ended

Dec. 31, 2019

Disclosure Text Block Supplement [Abstract]

IMPAIRMENTS

NOTE Z— IMPAIRMENTS

During the fourth quarter of 2019, similar to the fourth quarter of 2018, we experienced a sharp decline in customer demand for Northern White frac sand and for regional non-in-basin frac sand as more tons are produced and sold in-basin. Additionally, the price of frac sand decreased significantly. Given the changes in demand and customer preferences of local in-basin sand, we also experienced a significant decline in the utilization of the sand railcar fleet in our transload network. A significant number of sand railcars have been put into storage and are no longer used to deliver sand to our customers. In response to these economic conditions, we implemented numerous cost reductions including headcount reductions and a reduction of frac sand capacity at multiple locations.

As a result of the events described above, we have recorded impairment charges (in thousands) for the years ended December 31, 2019 and 2018 for the following assets:



Description	December 31, 2019		December 31, 2018
Inventories, net	$	4,100	$	3,316
Property, plant and mine development, net	243,064		109,938
Operating lease right-of-use assets	115,443		—
Goodwill	—		164,167
Intangible assets, net	1,240		4,478
Total	$	363,847	$	281,899

2019 Impairments

As a result of triggering events described above, which occurred in the fourth quarter of 2019, we completed an impairment assessment of our frac sand-related assets, including plant, property and mine development, right-of-use assets, inventories, and other intangible assets.

Inventories, net

We recorded impairment charges for unused inventory at frac sand plants we idled. These charges relate to the Oil & Gas Segment and are recorded in "Goodwill and other asset impairments" in the Consolidated Statements of Operations.

Property, plant and mine development

We estimated the future undiscounted net cash flows of asset groupings, which are at the plant level, using estimates of proven and probable sand reserves, estimated future sales prices (considering historical and current prices, price trends and related factors) and operating costs and anticipated capital expenditures. In the cases where the undiscounted cash flows are less than the carrying value of the assets, we recognized an impairment loss equal to the amount by which the carrying value exceeds the fair value of the assets. Impairment charges of approximately $243.1 million were recorded mainly related to facilities that have reduced capacity or have been idled, including Tyler, Texas, Sparta, Wisconsin, and Utica, Illinois. These charges relate to the Oil & Gas Segment and are recorded in "Goodwill and other asset impairments" in the Consolidated Statements of Operations.

Operating lease right-of-use assets

We determined the fair value of the railcars primarily utilizing internally developed cash flow models and quoted market prices, discounted at an appropriate weighted average cost of capital. As a result, we recognized impairment charges of approximately $115.4 million to write down the value of railcars to their estimated fair value. These charges relate mainly to the Oil & Gas Segment and are recorded in "Goodwill and other asset impairments" in the Consolidated Statements of Operations.

Intangible assets, net

We recorded a $1.2 million impairment of customer relationships related to the Oil & Gas segment that was recorded in the "Goodwill and other asset impairments" caption of our Consolidated Statements of Operations.

2018 Impairments

During the fourth quarter of 2018, we experienced a declining shift in demand for Northern White sand caused by some of our customers shifting to local in-basin frac sands with lower logistics costs. Our largest customer at our Voca, Texas plant did not renew their contract, instead opting to sign a new contract with us for local in-basin frac sand. Additionally, Northern White Sand operations and reserves in Fairchild, Wisconsin and Peru, Illinois experienced a similar significant fourth quarter decline in demand due to customers' shift to local in-basin sand closer to their operations.

As a result of these triggering events, we completed an impairment assessment of our frac sand-related assets, including plant, property and mine development, goodwill and other intangible assets.

Inventories, net

We recorded impairment charges for unused inventory related to the closure of our resin coating facility and associated product portfolio. These charges relate to the Oil & Gas Segment and are recorded in "Goodwill and other asset impairments" in the Consolidated Statements of Operations.

Property, plant and mine development

We estimated the future undiscounted net cash flows of asset groupings using estimates of proven and probable sand reserves, estimated future sales prices (considering historical and current prices, price trends and related factors) and operating costs and anticipated capital expenditures. In the cases where the undiscounted cash flows are less than the carrying value of the assets, we recognized an impairment loss equal to the amount by which the carrying value exceeds the fair value of the assets. Impairment charges of approximately $109.9 million were recorded mainly related to facilities that have reduced capacity, have been idled or were undeveloped, including Voca, Texas, Fairchild, Wisconsin, Rochelle, Illinois, and Peru, Illinois. These charges relate to the Oil & Gas Segment and are recorded in "Goodwill and other asset impairments" in the Consolidated Statements of Operations.

Goodwill and Intangible Assets, net

We performed a quantitative analysis and determined that the goodwill of our Oil & Gas Sand reporting unit was impaired. We recognized goodwill impairment charges of $164.2 million and intangible asset impairment charges related to trade names of $4.5 million during the fourth quarter of 2018. These impairment charges were recorded in the "Goodwill and other asset impairments" caption of our Consolidated Statements of Operations. The fair value of our reporting units was determined using a combination of the discounted cash flow method and the market multiples approach.

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2019
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	NOTE AA-SUBSEQUENT EVENTS On January 3, 2020, we paid a cash dividend of $4.6 million or $0.0625 per share to common stockholders of record on December 13, 2019, which had been declared by our Board of Directors on November 12, 2019. On February 10, 2020, our Board of Directors declared a quarterly cash dividend of $0.02 per share to common stockholders of record at the close of business on March 13, 2020, payable on April 3, 2020.

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation and Consolidation	Basis of Presentation and Consolidation The accompanying Consolidated Financial Statements have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”). In the opinion of management, all adjustments necessary for a fair presentation of the Consolidated Financial Statements have been included. Such adjustments are of a normal, recurring nature. Throughout this report we refer to (i) our Consolidated Balance Sheets as our “Balance Sheets,” (ii) our Consolidated Statements of Operations as our “Income Statements,” and (iii) our Consolidated Statements of Cash Flows as our “Cash Flows.”
Consolidation	Consolidation The Consolidated Financial Statements include the accounts of Holdings and its direct and indirect wholly-owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. We follow FASB Accounting Standards Codification (“ASC”) guidance for identification and reporting of entities over which control is achieved through means other than voting rights. The guidance defines such entities as Variable Interest Entities (“VIEs”). We consolidate VIEs when we have variable interests and are the primary beneficiary. We continually evaluate our involvement with VIEs to determine when these criteria are met.
Reclassifications	Reclassifications Certain reclassifications of prior period presentations have been made to conform to the current period presentation.
Use of Estimates and Assumptions	Use of Estimates and Assumptions The preparation of Consolidated Financial Statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the related disclosure of contingent assets and liabilities at the date of the Consolidated Financial Statements and the reported amounts of revenues and expenses during the reporting period. The more significant areas requiring the use of management estimates and assumptions relate to the purchase price allocation for businesses acquired; mineral reserves that are the basis for future cash flow estimates utilized in impairment calculations and units-of-production amortization calculations; environmental, reclamation and closure obligations; estimates of recoverable minerals; estimates of allowance for doubtful accounts; estimates of fair value for certain reporting units and asset impairments (including impairments of goodwill, intangible assets and other long-lived assets); write-downs of inventory to net realizable value; equity-based compensation expense; post-employment, post-retirement and other employee benefit liabilities; valuation allowances for deferred tax assets; contingent considerations; reserves for contingencies and litigation and the fair value and accounting treatment of financial instruments, including derivative instruments. We base our estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances. Accordingly, actual results may differ significantly from these estimates under different assumptions or conditions.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents consist of all highly liquid investments with a maturity of three months or less when purchased. Because of the short maturity of these investments, the carrying amounts approximate their fair value. Cash and cash equivalents are invested primarily in money market securities held by financial institutions with high credit ratings. Accounts at each institution are insured by the Federal Deposit Insurance Corporation. Cash balances at times may exceed federally-insured limits. We have not experienced any losses in such accounts and believe we are not exposed to any significant credit risk on cash.
Accounts Receivables	Accounts Receivable The majority of our accounts receivable are due from companies in the oil and natural gas drilling, building and construction products, filler and extenders, filtration, glass, absorbents, foundry, sports and recreation, and other major industries. Credit is extended based on evaluation of a customer’s financial condition and, generally, collateral is not required. Accounts receivable are stated at amounts due from customers net of an allowance for doubtful accounts. Accounts outstanding longer than the payment terms are considered past due. We determine our allowance by considering a number of factors, including the length of time trade accounts receivable are past due, our previous loss history, the customer’s current ability to pay its obligation to us, and the condition of the general economy and the industry as a whole. Ongoing credit evaluations are performed. We write-off accounts receivable when they are deemed uncollectible, and payments subsequently received on such receivables are credited to the allowance for doubtful accounts.
Inventories	Inventories Inventories include raw stockpiles, in-process product and finished product available for shipment, as well as spare parts and supplies for routine facility maintenance. We value inventory at the lower of cost and net realizable value. Cost is determined using the first-in, first-out and average cost methods. Our inventoriable costs include production costs and transportation and additional service costs as applicable.
Property, Plant and Mine Development	Property, Plant and Mine Development Plant and equipment Plant and equipment is recorded at cost and depreciated over their estimated useful lives. Interest incurred during construction of facilities is capitalized and depreciated over the life of the asset. Costs for normal repairs and maintenance that do not extend economic life or improve service potential are expensed as incurred. Costs of improvements that extend economic life or improve service potential are capitalized and depreciated over the estimated remaining useful life. Depreciation is recorded using the straight-line method over the assets’ estimated useful lives as follows: buildings (15 years); land improvements (10 years); machinery and equipment, including computer equipment and software (3-10 years); furniture and fixtures (8 years). Leasehold improvements are depreciated over the shorter of the asset life or lease term. Construction-in-progress is primarily comprised of machinery and equipment which have not yet been placed in service. Mining property and development Mining property and development includes mineral deposits and mine exploration and development. Mineral deposits are initially recognized at cost, which approximates the estimated fair value on the date of purchase. Mine exploration and development costs include engineering and mineral studies, drilling and other related costs to delineate an ore body, and the removal of overburden to initially expose an ore body for production. Costs incurred before mineralization are classified as proven and probable reserves are expensed and classified as exploration or advanced projects, research and development expense. Capitalization of mine development project costs, that meet the definition of an asset, begins once mineralization is classified as proven and probable reserves. The cost of removing overburden and waste materials to access the ore body at an open pit mine prior to the production phase are referred to as “pre-stripping costs.” Pre-stripping costs are capitalized during the development of an open pit mine. The production phase of an open pit mine commences when saleable minerals, beyond a de minimis amount, are produced. Stripping costs incurred during the production phase of a mine are variable production costs that are included as a component of inventory to be recognized in costs applicable to sales in the same period as the revenue from the sale of inventory. Depletion and amortization of mineral deposits and mine development costs are recorded as the minerals are extracted, based on units of production and engineering estimates of mineable reserves. The impact of revisions to reserve estimates is recognized on a prospective basis. See Note H - Property, Plant and Mine Development. Mine reclamation costs and asset retirement obligations We recognize the fair value of any liability for conditional asset retirement obligations, including environmental remediation liabilities when incurred, which is generally upon acquisition, construction or development and/or through the normal operation of the asset, if sufficient information exists to reasonably estimate the fair value of the liability. These obligations generally include the estimated net future costs of dismantling, restoring and reclaiming operating mines and related mine sites, in accordance with federal, state, local regulatory and land lease agreement requirements. The liability is accreted over time through periodic charges to earnings. In addition, the asset retirement cost is capitalized as part of the asset’s carrying value and amortized over the life of the related asset. Reclamation costs are periodically adjusted to reflect changes in the estimated present value resulting from the passage of time and revisions to the estimates of either the timing or amount of the reclamation and abandonment costs. The reclamation obligation is based on when spending for an existing environmental disturbance will occur. If the asset retirement obligation is settled for other than the carrying amount of the liability, a gain or loss is recognized on settlement. We review, on an annual basis, unless otherwise deemed necessary, the reclamation obligation at each mine site in accordance with ASC guidance for accounting for reclamation obligations.
Impairment or Disposal of Property, Plant and Mine Development	Impairment or Disposal of Property, Plant and Mine Development We periodically evaluate whether current events or circumstances indicate that the carrying value of our property, plant and equipment assets may not be recoverable. If circumstances indicate that the carrying value may not be recoverable, we estimate future undiscounted net cash flows using estimates of proven and probable sand reserves, estimated future sales prices (considering historical and current prices, price trends and related factors) and operating costs and anticipated capital expenditures. If the undiscounted cash flows are less than the carrying value of the assets, we recognize an impairment loss equal to the amount by which the carrying value exceeds the fair value of the assets. The recoverability of the carrying value of our mineral properties is dependent upon the successful development, start-up and commercial production of our mineral deposit and the related processing facilities. Our evaluation of mineral properties for potential impairment primarily includes assessing the existence or availability of required permits and evaluating changes in our mineral reserves, or the underlying estimates and assumptions, including estimated production costs. Assessing the economic feasibility requires certain estimates, including the prices of products to be produced and processing recovery rates, as well as operating and capital costs. Gains on the sale of property, plant and mine development are included in income when the assets are disposed of provided there is more than reasonable certainty of the collectability of the sales price and any future activities required to be performed by us relating to the disposal of the assets are complete or insignificant. Upon retirement or disposal of assets, all costs and related accumulated depreciation or amortization are written-off.
Goodwill and Other Intangible Assets and Related Impairment	Goodwill and Other Intangible Assets and Related Impairment Our intangible assets consist of goodwill, which is not being amortized, indefinite-lived intangibles, which consist of certain trade names that are not subject to amortization, intellectual property and customer relationships. Intellectual property mainly consists of patents and technology, and it is amortized on a straight-line basis over an average useful life of 15 years. Customer relationships are amortized on a straight-line basis over their useful life of 20, 15 or 13 years. Goodwill represents the excess of the purchase price of business combinations over the fair value of net assets acquired. Goodwill and trade names are reviewed for impairment annually as of October 31, or more frequently when indicators of impairment exist. An impairment exists if the fair value of a reporting unit to which goodwill has been allocated, or the fair value of indefinite-lived intangible assets, is less than their respective carrying values. Prior to conducting a formal impairment test, we have an option to assess qualitative factors to determine whether the existence of events or circumstances leads to a determination that is more likely than not (more than 50%) that the fair value of a reporting unit is less than its carrying amount. Such qualitative factors may include the following: macroeconomic conditions; industry and market considerations; cost factors; overall financial performance; and other relevant entity-specific events. If the qualitative assessment determines that an impairment is more likely than not, or if we choose to bypass the qualitative assessment, we perform a quantitative assessment by comparing the fair value of a reporting unit with its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit.
Leases	Leases We lease railroad cars, office space, mining property, mining/processing equipment and transportation and other equipment. Operating leases are included in operating lease right-of-use (“ROU”) assets, current portion of operating lease liabilities, and operating lease liabilities in our consolidated balance sheets. Finance leases are included in property, plant and mine development, current portion of long-term debt, and long-term debt in our consolidated balance sheets. Leases with an initial term of 12 months or less are not recorded on the balance sheet. ROU assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. ROU assets and liabilities are recognized at the commencement date of the lease based on the present value of lease payments over the lease term. As most of our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. The ROU assets also include any lease payments made at or before the commencement date of the lease and excludes lease incentives. Our lease terms may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Lease expense for lease payments is recognized on a straight-line basis over the lease term. We have lease agreements with lease and non-lease components, the latter of which are generally accounted for separately. See Note S - Leases. We periodically evaluate whether current events or circumstances indicate that the carrying value of our right-of-use assets exceeds fair value. If circumstances indicate an impairment exists, we estimate fair value primarily utilizing internally developed cash flow models and quoted market prices, discounted at an appropriate weighted average cost of capital. If the undiscounted cash flows are less than the carrying value of the assets, we recognize an impairment loss equal to the amount by which the carrying value exceeds the fair value of the assets.
Revenue Recognition and Deferred Revenues	Revenue Recognition Products We derive our product sales by mining and processing minerals that our customers purchase for various uses. Our product sales are primarily a function of the price per ton and the number of tons sold. We primarily sell our products through individual purchase orders executed under short-term price agreements or at prevailing market rates. The amount invoiced reflects product, transportation and / or additional handling services as applicable, such as storage, transloading the product from railcars to trucks and last mile logistics to the customer site. We invoice most of our product customers on a per shipment basis, although for some larger customers, we consolidate invoices weekly or monthly. Standard collection terms are net 30 days, although extended terms are offered in competitive situations. We recognize revenue for products and materials at a point in time following the transfer of control of such items to the customer, which typically occurs upon shipment or delivery depending on the terms of the underlying contracts. We account for shipping and handling activities related to product and material sales contracts with customers as costs to fulfill our promise to transfer the associated products pursuant to the accounting policy election allowed under ASC 606-10-25-18b. Accordingly, we record amounts billed for shipping and handling costs as a component of net sales and accrue and classify related costs as a component of cost of sales at the time revenue is recognized. For a limited number of customers, we sell under long-term, minimum purchase supply agreements. These agreements define, among other commitments, the volume of product that our customers must purchase, the volume of product that we must provide and the price that we will charge and that our customers will pay for each product. Prices under these agreements are generally fixed and subject to certain contractual adjustments. Sometimes these agreements may undergo negotiations regarding pricing and volume requirements, which may often occur in volatile market conditions. While these negotiations continue, we may deliver sand at prices or at volumes below the requirements in our existing supply agreements. An executed order specifying the type and quantity of product to be delivered, in combination with the noted agreements, comprise our contracts in these arrangements. Service We derive our service revenues primarily through the provision of transportation, equipment rental, and contract labor services to companies in the oil and gas industry. Transportation services typically consist of transporting customer proppant from storage facilities to proximal well-sites and are contracted through work orders executed under established pricing agreements. The amount invoiced reflects the transportation services rendered. Equipment rental services provide customers with use of either dedicated or nonspecific wellhead proppant delivery equipment solutions for contractual periods defined either through formal lease agreements or executed work orders under established pricing agreements. The amounts invoiced reflect the length of time the equipment set was utilized in the billing period. Contract labor services provide customers with proppant delivery equipment operators through work orders executed under established pricing agreements. The amounts invoiced reflect the amount of time our labor services were utilized in the billing period. We typically invoice our customers on a weekly or monthly basis; however, some customers receive invoices upon well-site operation completion. Standard collection terms are net 30 days, although extended terms are offered in competitive situations. We typically recognize revenue for specific, dedicated equipment set rental arrangements under ASC 842, Leases. For the remaining components of service revenue, we have applied the practical expedient allowed under ASC 606-10-55-18 to recognize transportation revenues in proportion to the amount we have the right to invoice. Contracts with Multiple Performance Obligations From time to time, we may enter into contracts that contain multiple performance obligations, such as work orders containing a combination of product, transportation, equipment rentals, and contract labor services. For these arrangements, we allocate the transaction price to each performance obligation identified in the contract based on relative standalone selling prices, or estimates of such prices, and recognize the related revenue as control of each individual product or service is transferred to the customer, in satisfaction of the corresponding performance obligations. We typically invoice our customers on a weekly or monthly basis; however, some customers receive invoices upon well-site operation completion. Standard collection terms are net 30 days, although extended terms are offered in competitive situations. Taxes Collected from Customers and Remitted to Governmental Authorities. We exclude from our measurement of transaction prices all taxes assessed by governmental authorities that are both (i) imposed on and concurrent with a specific revenue-producing transaction and (ii) collected from customers. Accordingly, such tax amounts are not included as a component of net sales or cost of sales. See Note U - Revenue. Deferred Revenues For a limited number of customers, we enter into supply agreements which give customers the right to make advanced payments toward the purchase of certain products at specified volumes over an average initial period of one to fifteen years. These payments represent consideration that is unconditional for which we have yet to transfer the related product. These payments are recorded as contract liabilities referred to as “deferred revenues” upon receipt and recognized as revenue upon delivery of the related product.
Unbilled Receivables	Unbilled Receivables Revenues recognized in advance of invoice issuance create assets referred to as “unbilled receivables.” Any portion of our unbilled receivables for which our right to consideration is conditional on a factor other than the passage of time is considered a contract asset. These assets are presented on a combined basis with accounts receivable and are converted to accounts receivable once billed.
Debt Issuance Costs	Debt Issuance Costs The Company defers costs directly associated with acquiring third-party financing, primarily loan origination costs and related professional expenses. Debt issuance costs are deferred and amortized using the effective interest rate method over the term of our senior secured Term Loan facility and the straight-line method for our Revolver facility. Debt issuance costs related to long-term debt are reflected as a direct deduction from the carrying amount of the debt.
Employee Benefit Plans	Employee Benefit Plans We provide a range of benefits to our employees and retired employees, including pensions and post-retirement healthcare and life insurance benefits. We record annual amounts relating to these plans based on calculations specified by generally accepted accounting principles, which include various actuarial assumptions, including discount rates, assumed rates of returns, compensation increases, turnover rates, mortality table, and healthcare cost trend rates. We review the actuarial assumptions on an annual basis and make modifications to the assumptions based on current rates and trends when it is deemed appropriate to do so. As required by U.S. generally accepted accounting principles, the effect of the modifications is generally recorded or amortized over future periods. We believe that the assumptions utilized in recording our obligations under the plans are reasonable based on advice from our actuaries and information as to assumptions used by other employers.
Environmental Costs	Environmental Costs Environmental costs, other than qualifying capital expenditures, are accrued at the time the exposure becomes known and costs can be reasonably estimated. Costs are accrued based upon management’s estimates of all direct costs, after taking into account expected reimbursement by third parties (primarily the sellers of acquired businesses) and are reviewed by outside consultants. Environmental costs are charged to expense unless a settlement with an indemnifying party has been reached.
Self-Insurance	Self-Insurance We are self-insured for various levels of employee health insurance coverage, workers’ compensation and third-party product liability claims alleging occupational disease. We purchase insurance coverage for claim amounts which exceed our self-insured retentions. Depending on the type of insurance, these self-insured retentions range from $0.1 million to $0.5 million per occurrence. Our insurance reserves are accrued based on estimates of the ultimate cost of claims expected to occur during the covered period. Our insurance reserves are accrued based on estimates of the ultimate cost of claims expected to occur during the covered period. These estimates are prepared with the assistance of outside actuaries and consultants. Our actuaries periodically review the volume and amount of claims activity, and based upon their findings, we adjust our insurance reserves accordingly. The ultimate cost of claims for a covered period may differ from our original estimates. The current portion of our self-insurance reserves is included in accrued liabilities and the non-current portion is included in other long-term obligations in our Balance Sheets.
Research and Development Costs	Research and Development Costs We may incur immaterial internal research and development (“R&D”) expenditures, and research and development conducted for others, all of which are expensed as incurred, and included in selling, general and administrative expense. R&D costs may include, but are not limited to, research and administrative salaries, contractor fees, building costs, utilities, administrative expenses, and allocations of corporate costs.
Advertising Costs	Advertising Costs We recognize advertising expense when incurred as selling, general and administrative expense.
Equity-based Compensation	Equity-based Compensation We grant stock options, restricted stock, restricted stock units and performance share units to certain of our employees and directors under the Amended and Restated U.S. Silica Holdings, Inc. 2011 Incentive Compensation Plan. We recognize the cost of employee services rendered in exchange for awards of equity instruments. Vesting of restricted stock and restricted stock units is based on the individual continuing to render service over a pre-defined vesting schedule, generally three years. Cash dividend equivalents are accrued and paid to the holders of time-based restricted stock units and restricted stock. The fair value of the restricted stock awards is equal to the market price of our stock at date of grant. The restricted award-related compensation expense is recognized, on a straight-line basis, over the vesting period. We grant performance share units to certain employees in which the number of shares of common stock ultimately received is determined based on achievement of certain performance thresholds over a specified performance period (generally three years) in accordance with the stock award agreement. Cash dividend equivalents are not accrued or paid on performance share units. We recognize expense based on the estimated vesting of our performance share units granted and the grant date market price. The estimated vesting of the performance share units is principally based on the probability of achieving certain financial performance levels during the vesting periods. In the period it becomes probable that the minimum performance criteria specified in the award agreement will be achieved, we recognize expense for the proportionate share of the total fair value of the award related to the vesting period that has already lapsed. The remaining fair value of the award is expensed on a straight-line basis over the remaining vesting period. We grant certain employees performance share units, the vesting of which is based on the Company’s total shareholder return (“TSR”) ranking among a peer group over a three-year period. The number of units that will vest will depend on the percentage ranking of the Company's TSR compared to the TSRs for each of the companies in the peer group over the performance period. For these awards subject to market conditions, a binomial-lattice model (i.e., Monte Carlo simulation model) is used to fair value these awards at grant date. The related compensation expense is recognized, on a straight-line basis, over the vesting period. We grant stock options to certain employees and directors. Stock options vest on a vesting schedule and the related compensation expense is recognized over the vesting period, usually over 3 or 4 years. In calculating the compensation expense for stock options granted, we estimate the fair value of each grant using the Black-Scholes option-pricing model. The fair value of stock options granted is based on the exercise price of the option and certain assumptions, which are evaluated and revised, as necessary, to reflect market conditions and experience. We account for forfeitures as they occur. Our expected term is the period of time over which the options are expected to remain outstanding. An increase in the expected term will increase compensation expense. The computation of the expected term is based on the simplified method, under which the expected term is presumed to be the mid-point between the average vesting date and the end of the contractual term. The assumptions for expected volatility are based on historical experience for the same periods as our expected lives. Risk-free interest rates are set using grant-date U.S. Treasury yield curves for the same periods as our expected lives. The expected dividend yield is based on our future dividend expectations for the same periods as our expected lives.
Income Taxes	Income Taxes Deferred taxes are provided on the liability method whereby deferred tax assets are recognized for deductible temporary differences and operating loss and tax credit carry forwards and deferred tax liabilities are recognized for taxable temporary differences. This approach requires recognition of deferred tax liabilities and assets for the expected future tax consequences of events that have been included in the financial statements or tax returns. Under this method, deferred tax liabilities and assets are determined based upon the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the expenses are expected to reverse. Valuation allowances are provided if, based on the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. We recognize a tax benefit associated with an uncertain tax position when, in management’s judgment, it is more likely than not that the position will be sustained upon examination by a taxing authority. For a tax position that meets the more-likely-than-not recognition threshold, we initially and subsequently measure the tax benefit as the largest amount that we judge to have a greater than 50% likelihood of being realized upon ultimate settlement with a taxing authority. The liability associated with unrecognized tax benefits is adjusted periodically due to changing circumstances, such as the progress of tax audits, case law developments and new or emerging legislation. Such adjustments are recognized entirely in the period in which they are identified. The effective tax rate includes the net impact of changes in the liability for unrecognized tax benefits and subsequent adjustments as considered appropriate by management. The largest permanent item in computing both our effective tax rate and taxable income is the deduction allowed for statutory depletion. The deduction for statutory depletion does not necessarily change proportionately to changes in income before income taxes.
Financial Instruments	Financial Instruments We currently use interest rate hedge agreements to manage interest costs and the risk associated with changing interest rates. Amounts to be paid or received under these hedge agreements are accrued as interest rates change and are recognized over the life of the hedge agreements as an adjustment to interest expense. Our policy is to not hold or issue derivative financial instruments for trading or speculative purposes. When entered into, these financial instruments are designated as hedges of underlying exposures, associated with our long-term debt, and are monitored to determine if they remain effective hedges. Gains and losses on derivatives designated as cash flow hedges are recorded in other comprehensive income (loss), net of tax, and reclassified to earnings in a manner that matches the timing of the earnings impact of the hedged transactions. The ineffective portion of all hedges, if any, is recognized currently in income.
Foreign Currency Translation	Foreign Currency Translation For our operations in countries where the functional currency is other than the U.S. dollar, balance sheet amounts are translated using the exchange rate in effect at the balance sheet date. Income statement amounts are translated monthly using the average exchange rate for the respective month. The gains and losses resulting from the changes in exchange rates from year-to-year are recorded as a component of accumulated other comprehensive income or loss as currency translation adjustments, net of tax. Any gains or losses on transactions in currencies other than the functional currency are included in other income (expense), net, including interest income.
Comprehensive Income (Loss)	Comprehensive Income (loss) In addition to net income (loss), comprehensive income (loss) includes all changes in equity during a period, such as adjustments to minimum pension liabilities and the effective portion of changes in fair value of derivative instruments that qualify as cash flow hedges.
Business Combinations	Business Combinations The Company accounts for business combinations using the acquisition method of accounting. Under this method, acquired assets, including separately identifiable intangible assets and any assumed liabilities, are recorded at their acquisition date estimated fair value. The excess of purchase price over the fair value amounts assigned to the assets acquired and liabilities assumed represents the goodwill amount resulting from the acquisition. Determining the fair value of assets acquired and liabilities assumed involves the use of significant estimates and assumptions.
New Accounting Pronouncements Recently Adopted and New Accounting Pronouncements Not Yet Adopted	New Accounting Pronouncements Recently Adopted In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) and issued ASU 2018-11 Leases (Topic 842): Targeted Improvements. The new standard(s) established a right-of-use ("ROU") model that requires a lessee to record an ROU asset and a corresponding lease liability on the balance sheet for all leases with terms greater than 12 months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition. Similarly, lessors will be required to classify leases as sales-type, finance or operating, with classification affecting the pattern of income recognition. Classification for both lessees and lessors will be based on an assessment of whether the lease risks and rewards, as well as substantive control, have been transferred through a lease contract. On January 1, 2019, we adopted the new accounting standard using the modified retrospective approach. We elected the package of practical expedients permitted under the transition guidance, which allowed us to account for our existing operating leases without reassessing (a) whether the contracts contain a lease under the new standard, (b) whether classification of the operating leases would be different in accordance with the new standard, or (c) whether the unamortized initial direct costs before transition adjustments would have met the definition of initial direct costs in the new standard at lease commencement. Adoption of the new standard resulted in the recognition of operating lease ROU assets of $223.0 million, which we have subsequently impaired during 2019 by $115.4 million, and lease liabilities of $222.7 million. The standard did not have a material impact on our consolidated statements of operations or cash flows. The comparative information has not been restated and continues to be reported under the accounting standards in effect for those periods. See Note S - Leases. In February 2018, the FASB issued Accounting Standards Update ASU 2018-02, Income Statement-Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. The ASU provides that the stranded tax effects from the Tax Cuts and Jobs Act of 2017 in accumulated other comprehensive loss may be reclassified to retained earnings. The ASU was effective January 1, 2019, with early adoption permitted. We adopted the new accounting standard on January 1, 2019, and we do not intend to exercise the option to reclassify stranded tax effects within accumulated other comprehensive income. New Accounting Pronouncements Not Yet Adopted In August 2018, the FASB issued ASU 2018-14, Compensation - Retirement Benefits - Defined Benefit Plans - General (Subtopic 715-20). The new guidance removes certain disclosure requirements for employers which sponsor defined benefit pension or other post-retirement plans, but also adds disclosure requirements for the weighted average interest crediting rates for cash balance plans and other plans with promised crediting rates and an explanation of the reasons for significant gains and losses related to changes in the benefit obligation for the period. The amendments also clarify disclosure requirements for the projected benefit obligation (PBO) and accumulated benefit obligation (ABO) and fair value of plan assets for plans with PBOs and ABOs in excess of plan assets. Entities should apply the amendments on a retrospective basis for all periods presented. The amendments in this Update are effective for public entities for fiscal years ending after December 15, 2020. We are currently evaluating the effect the guidance will have on our disclosures. In August 2018, the FASB issued ASU 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. The new guidance requires a customer in a cloud computing arrangement (i.e., hosting arrangement) that is a service contract to follow the internal-use software guidance in ASC 350-40 to determine which implementation costs to capitalize as assets or expense as incurred. Capitalized implementation costs related to a hosting arrangement that is a service contract will be amortized over the term of the hosting arrangement, beginning when the module or component of the hosting arrangement is ready for its intended use. The update is effective for calendar-year public business entities in 2020. We plan to adopt this guidance on a prospective basis and do not expect the adoption to have a significant impact on our Consolidated Statements of Operation. In November 2018, the FASB issued ASU 2018-19, Codification Improvements to Topic 326, Financial Instruments-Credit Losses. The amendments in this ASU clarified issues related to Topic 326. In Issue 1, the amendment in this ASU mitigate transition complexity by requiring that for nonpublic business entities the amendments in ASU 2016-13 are effective for fiscal years after December 15, 2021, including interim periods within those fiscal years. In Issue 2, the amendment clarifies that receivables arising from operating leases are not within the scope of Subtopic 326-20. Impairment of receivables arising from operating leases should be accounted for in accordance with Topic 842, Leases. The ASU is effective for all entities for fiscal years beginning after December 15, 2019, including interim periods therein. We expect the adoption of this standard will primarily impact our accounts receivable allowance estimating process, but do not expect a material impact to our consolidated financial statements. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. The amendments in this Update simplify the accounting for income taxes by removing several exceptions and also simplify the accounting for income taxes by requiring that an entity recognize a franchise tax (or similar tax) that is partially based on income as an income-based tax and account for any incremental amount incurred as a non-income-based tax, requiring that an entity evaluate when a step up in the tax basis of goodwill should be considered part of the business combination in which the book goodwill was originally recognized and when it should be considered a separate transaction, specifying that an entity is not required to allocate the consolidated amount of current and deferred tax expense to a legal entity that is not subject to tax in its separate financial statements (however, an entity may elect to do so on an entity-by-entity basis) for a legal entity that is both not subject to tax and disregarded by the taxing authority, requiring that an entity reflect the effect of an enacted change in tax laws or rates in the annual effective tax rate computation in the interim period that includes the enactment date, and making minor codification improvements for income taxes related to employee stock ownership plans and investments in qualified affordable housing projects accounted for using the equity method. For public business entities, the amendments in this Update are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. We are currently evaluating the effect that the guidance will have on our financial statements and related disclosures.
Fair Value Measurement	Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Fair value is estimated by applying the following hierarchy, which prioritizes the inputs used to measure fair value into three levels and bases the categorization within the hierarchy upon the lowest level of input that is available and significant to the fair value measurement: Level 1—Quoted prices in active markets for identical assets or liabilities. Level 2—Observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3—Inputs that are generally unobservable and typically reflect management’s estimate of assumptions that market participants would use in pricing the asset or liability. Cash Equivalents Due to the short-term maturity, we believe our cash equivalent instruments at December 31, 2019 and 2018, approximate their reported carrying values. Long-Term Debt, Including Current Maturities We believe that the fair values of our long-term debt, including current maturities, approximate their carrying values based on their effective interest rates compared to current market rates. Changes in the fair value of the royalty note payable utilize Level 3 inputs, such as estimates of future tonnages sold and average sales price. See Note K - Debt for more information on the change in fair value during the year ended December 31, 2019. Derivative Instruments The estimated fair value of our derivative instruments are recorded at each reporting period and are based upon widely accepted valuation techniques, including discounted cash flow analysis on the expected cash flows of each derivative contract. This analysis reflects the contractual terms of the derivatives, including the period to maturity, and uses observable market-based inputs, including interest rate curves and implied volatilities. We also incorporate credit valuation adjustments to appropriately reflect both our nonperformance risk as well as that of the respective counterparty in the fair value measurements. Although we have determined that the majority of the inputs used to value our derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with our derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default of ourselves and our counterparties. However, as of December 31, 2019, we have assessed that the impact of the credit valuation adjustments on the overall valuation of our derivative positions is not significant. As a result, we have determined that our derivative valuations in their entirety are classified in Level 2 of the fair value hierarchy.

Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2019

Earnings Per Share [Abstract]

Schedule of Computation of Basic and Diluted Earnings Per Share

The following table shows the computation of basic and diluted earnings per share for the years ended December 31, 2019, 2018 and 2017:



In thousands, except per share amounts	Year ended December 31,
	2019			2018			2017
Numerator:
Net (loss) income attributable to U.S. Silica Holdings, Inc.	$	(329,082	)	$	(200,808	)	$	145,206

Denominator:
Weighted average shares outstanding	73,253			76,453			81,051
Diluted effect of stock awards	—			—			909
Weighted average shares outstanding assuming dilution	73,253			76,453			81,960

(Loss) earnings per share attributable to U.S. Silica Holdings, Inc.:
Basic (loss) earnings per share	$	(4.49	)	$	(2.63	)	$	1.79
Diluted (loss) earnings per share	$	(4.49	)	$	(2.63	)	$	1.77

Schedule of Antidilutive Securities Excluded from Computation of Diluted Earnings Per Share

Certain stock options, restricted stock awards and performance share units were excluded from the computation of diluted earnings per share because their effect would have been anti-dilutive. Such stock awards (in thousands) excluded from the calculation of diluted earnings (loss) per common share were as follows:



	Year ended December 31,
	2019	2018	2017
Stock options excluded	711	574	195
Restricted stock and performance share units awards excluded	1,298	155	305

Capital Structure and Accumulated Other Comprehensive Income (Loss) (Tables)

12 Months Ended

Dec. 31, 2019

Equity [Abstract]

Schedule of Declared Quarterly Cash Dividends

During the year ended December 31, 2019, our Board of Directors declared quarterly cash dividends as follows:



Dividends per Common Share		Declaration Date	Record Date	Payable Date
$	0.0625	February 15, 2019	March 14, 2019	April 4, 2019
$	0.0625	May 13, 2019	June 14, 2019	July 5, 2019
$	0.0625	July 18, 2019	September 13, 2019	October 3, 2019
$	0.0625	November 12, 2019	December 13, 2019	January 3, 2020

Schedule of Changes in Accumulated Other Comprehensive Income (Loss)

The following table presents the changes in accumulated other comprehensive loss by component (in thousands) during the year ended December 31, 2019:



	For the Year Ended December 31, 2019
	Unrealized loss on cash flow hedges			Foreign currency translation adjustments			Pension and other post-retirement benefits liability			Total
Beginning Balance	$	(1,621	)	$	(620	)	$	(12,779	)	$	(15,020	)
Other comprehensive loss before reclassifications	(1,432		)	(188		)	(4,450		)	(6,070		)
Amounts reclassed from accumulated other comprehensive loss	—			—			1,236			1,236
Ending Balance	$	(3,053	)	$	(808	)	$	(15,993	)	$	(19,854	)

Business Combinations (Tables)

12 Months Ended

Dec. 31, 2019

Business Combinations [Abstract]

Schedule of Identifiable Assets Acquired and Liabilities Assumed



	Estimate as of December 31, 2017		Measurement Period Adjustments			Purchase Price Allocation
Accounts receivable	$	11,201	$	—		$	11,201
Inventories	8,067		—			8,067
Other current assets	362		—			362
Assets held for sale	9,453		—			9,453
Property, plant and mine development	27,458		—			27,458
Mineral rights	26,300		(2,800		)	23,500
Other non-current assets	1,136		—			1,136
Goodwill	22,522		2,800			25,322
Customer relationships	1,840		—			1,840
Total assets acquired	108,339		—			108,339
Accounts payable and accrued expenses	3,761		—			3,761
Unfavorable leasehold positions	2,237		—			2,237
Notes Payable	866		—			866
Other long term liabilities	—		—			—
Asset retirement obligations	474		—			474
Total liabilities assumed	7,338		—			7,338
Net assets acquired	$	101,001	$	—		$	101,001



Final allocation of purchase price:	Estimate as of December 31, 2018		Measurement Period Adjustments			Purchase Price Allocation
Accounts receivable, net	$	43,305	$	—		$	43,305
Inventories	86,112		—			86,112
Property, plant and mine development	148,495		(1,937		)	146,558
Mineral rights	419,469		(10,580		)	408,889
Identifiable intangible assets - finite lived	10,270		(1,500		)	8,770
Identifiable intangible assets - indefinite lived	38,050		(1,250		)	36,800
Prepaids and deposits	2,072		(245		)	1,827
Other assets	7,474		—			7,474
Goodwill	150,628		12,184			162,812
Total assets acquired	905,875		(3,328		)	902,547
Accounts payable	13,435		—			13,435
Accrued expenses and other current liabilities	10,304		—			10,304
Deferred tax liabilities	122,811		(3,328		)	119,483
Long term obligations	16,076		—			16,076
Total liabilities assumed	$	162,626	$	(3,328	)	$	159,298
Net assets acquired	$	743,249	$	—		$	743,249

Schedule of Identifiable Intangible Assets Acquired

The acquired intangible assets and the related estimated useful lives consist of the following:



	Approximate Fair Value		Estimated Useful Life
	(in thousands)		(in years)
Customer relationships	$	1,840	15

The acquired intangible assets and the related estimated useful lives consist of the following:



	Approximate Fair Value		Estimated Useful Life
	(in thousands)		(in years)
Technology and intellectual property	$	1,400	15
Customer relationships	7,370		15
Total identifiable intangible assets - finite lived	$	8,770

Trade names	$	36,800
Total identifiable intangible assets - indefinite lived	$	36,800

Schedule of Pro Forma Information

The following unaudited pro forma consolidated financial information reflects the results of operations as if the EPMH acquisition had occurred on January 1, 2017, after giving effect to certain purchase accounting adjustments. Material non-recurring transaction costs attributable to the business combination were $15.2 million. Pro forma net income includes incremental interest expense due to the related debt financing, incremental depreciation and depletion expense related to the fair value adjustment of property, plant and mine development, amortization expense related to identifiable intangible assets, and tax expense related to the combined tax provisions. This information does not purport to be indicative of the actual results that would have occurred if the acquisition had actually been completed on the date indicated, nor is it necessarily indicative of the future operating results or the financial position of the combined company (in thousands, except per share amounts):



	For the year ended December 31,
	2018			2017
Sales	$	1,659,775		$	1,454,070
Net (loss) income	$	(179,220	)	$	116,899
Basic (loss) earnings per share	$	(2.34	)	$	1.44
Diluted (loss) earnings per share	$	(2.34	)	$	1.43

The following unaudited pro forma consolidated financial information reflects the results of operations as if the MS Sand Acquisition had occurred on January 1, 2016, after giving effect to certain purchase accounting adjustments. These adjustments mainly include incremental depreciation expense related to the fair value adjustment of property, plant, equipment and mine development, amortization expense related to identifiable intangible assets and tax expense related to the combined tax provisions. This information does not purport to be indicative of the actual results that would have occurred if the acquisition had actually been completed on the date indicated, nor is it necessarily indicative of the future operating results or the financial position of the combined company (in thousands, except per share amounts):



	For the year ended December 31,
	2017
Sales	$	1,287,202
Net income	$	143,604
Basic earnings per share	$	1.77
Diluted earnings per share	$	1.75

Accounts Receivable (Tables)

12 Months Ended

Dec. 31, 2019

Receivables [Abstract]

Schedule of Accounts Receivable and Allowance for Doubtful Accounts

At December 31, 2019 and December 31, 2018, accounts receivable (in thousands) consisted of the following:



	December 31, 2019			December 31, 2018
Trade receivables	$	178,182		$	198,435
Less: Allowance for doubtful accounts	(8,984		)	(6,751		)
Net trade receivables	169,198			191,684
Other receivables⁽¹⁾	13,040			23,802
Total accounts receivable	$	182,238		$	215,486



(1	)	At December 31, 2019, other receivables include $8.1 million of refundable alternative minimum tax credits. At December 31, 2018, other receivables included $16.0 million of refundable alternative minimum tax credits that were refunded during the third quarter of 2019.

Changes in our allowance for doubtful accounts (in thousands) during the years ended December 31, 2019 and 2018 were as follows:



	December 31, 2019			December 31, 2018
Beginning balance	$	6,751		$	7,100
Bad debt provision	3,466			315
Write-offs	(1,233		)	(664		)
Ending balance	$	8,984		$	6,751

Inventories (Tables)

12 Months Ended

Dec. 31, 2019

Inventory Disclosure [Abstract]

Schedule of Inventories

At December 31, 2019 and December 31, 2018, inventories (in thousands) consisted of the following:



	December 31, 2019		December 31, 2018
Supplies	$	47,277	$	41,453
Raw materials and work in process	41,167		68,474
Finished goods	35,988		52,160
Total inventories	$	124,432	$	162,087

Property, Plant and Mine Development (Tables)

12 Months Ended

Dec. 31, 2019

Property, Plant and Equipment [Abstract]

Schedule of Property, Plant and Mine Development

At December 31, 2019 and December 31, 2018, property, plant and mine development (in thousands) consisted of the following:



	December 31, 2019			December 31, 2018
Mining property and mine development	$	794,899		$	995,759
Asset retirement cost	18,260			12,732
Land	57,082			55,502
Land improvements	73,203			67,729
Buildings	69,112			64,515
Machinery and equipment	1,152,898			958,357
Furniture and fixtures	4,068			3,599
Construction-in-progress	54,675			167,933
	2,224,197			2,326,126
Accumulated depletion, depreciation, amortization and impairment charges	(706,610		)	(499,823		)
Total property, plant and mine development, net	$	1,517,587		$	1,826,303

Goodwill and Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Changes in the Carrying Amount of Goodwill

The changes in the carrying amount of goodwill (in thousands) by business segment consisted of the following:



	Oil & Gas Proppants Segment			Industrial & Specialty Products Segment		Total
Balance at December 31, 2017	247,467			24,612		272,079

MS Sand acquisition measurement period adjustment	2,800			—		2,800
EPMH acquisition and measurement period adjustment	—			150,628		150,628
Oil & Gas Sand impairment	(164,167		)	—		(164,167		)

Goodwill	250,267			175,240		425,507
Impairment losses	(164,167		)	—		(164,167		)
Balance at December 31, 2018	86,100			175,240		261,340

EPMH acquisition measurement period adjustment	—			12,184		12,184
Balance at December 31, 2019	$	86,100		$	187,424	$	273,524

Schedule of Changes in the Carrying Amount of Definite-Lived Intangible Assets

The changes in the carrying amount of intangible assets (in thousands) consisted of the following:



	December 31, 2019										December 31, 2018
	Gross Carrying Amount		Accumulated Amortization			Impairments			Net		Gross Carrying Amount		Accumulated Amortization			Impairments			Net

Technology and intellectual property	$	86,183	$	(17,080	)	—			$	69,103	$	83,616	$	(11,168	)	—			$	72,448
Customer relationships	68,599		(18,737		)	$	(1,240	)	48,622		68,664		(13,826		)	—			54,838
Total definite-lived intangible assets:	$	154,782	$	(35,817	)	$	(1,240	)	$	117,725	$	152,280	$	(24,994	)	$	—		$	127,286
Trade names	65,390		—			—			65,390		71,118		—			(4,478		)	66,640
Other	700		—			—			700		700		—			—			700
Total intangible assets:	$	220,872	$	(35,817	)	$	(1,240	)	$	183,815	$	224,098	$	(24,994	)	$	(4,478	)	$	194,626

Schedule of Changes in the Carrying Amount of Indefinite-Lived Intangible Assets

The changes in the carrying amount of intangible assets (in thousands) consisted of the following:



	December 31, 2019										December 31, 2018
	Gross Carrying Amount		Accumulated Amortization			Impairments			Net		Gross Carrying Amount		Accumulated Amortization			Impairments			Net

Technology and intellectual property	$	86,183	$	(17,080	)	—			$	69,103	$	83,616	$	(11,168	)	—			$	72,448
Customer relationships	68,599		(18,737		)	$	(1,240	)	48,622		68,664		(13,826		)	—			54,838
Total definite-lived intangible assets:	$	154,782	$	(35,817	)	$	(1,240	)	$	117,725	$	152,280	$	(24,994	)	$	—		$	127,286
Trade names	65,390		—			—			65,390		71,118		—			(4,478		)	66,640
Other	700		—			—			700		700		—			—			700
Total intangible assets:	$	220,872	$	(35,817	)	$	(1,240	)	$	183,815	$	224,098	$	(24,994	)	$	(4,478	)	$	194,626

Schedule of Estimated Amortization Expense Related to Definite-Lived Intangible Assets

The estimated amortization expense related to definite-lived intangible assets (in thousands) for the five succeeding years is as follows:



2020	$	10,863
2021	10,861
2022	10,846
2023	10,841
2024	10,843

Accounts Payable and Accrued Liabilities (Tables)

12 Months Ended

Dec. 31, 2019

Payables and Accruals [Abstract]

Schedule of Accounts Payables and Accrued Liabilities

At December 31, 2019 and 2018, accounts payable and accrued liabilities (in thousands) consisted of the following:



	December 31,
	2019		2018
Trade payables	$	181,029	$	166,296
Accrued salaries and wages	12,385		12,291
Accrued vacation liability	3,053		3,503
Current portion of liability for pension and post-retirement benefits	2,993		2,708
Accrued healthcare liability	4,078		2,702
Accrued property taxes and sales taxes	4,070		4,490
Vendor incentives	26,617		12,508
Other accrued liabilities	14,012		11,902
Accounts payable and accrued liabilities	$	248,237	$	216,400

Debt (Tables)

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

Schedule of Debt

At December 31, 2019 and 2018, debt (in thousands) consisted of the following:



	December 31, 2019			December 31, 2018
Senior secured credit facility:
Revolver expiring May 1, 2023 (7.75% at December 31, 2019 and 8.50% at December 31, 2018)	$	—		$	—
Term Loan facility—final maturity May 1, 2025 (5.81% at December 31, 2019 and 6.56% December 31, 2018)	1,247,600			1,270,400
Less: Unamortized original issue discount	(5,412		)	(6,511		)
Less: Unamortized debt issuance cost	(25,390		)	(31,310		)
Note payable secured by royalty interest	10,438			26,511
Insurance financing notes payable	5,055			—
Equipment notes payable	87			321
Finance leases	70			344
Total debt	1,232,448			1,259,755
Less: current portion	(18,463		)	(13,327		)
Total long-term portion of debt	$	1,213,985		$	1,246,428

Schedule of Contractual Maturities of Debt

The minimum payments (in thousands) for the next five years required by the note are as follows:



2020	$	454
2021	378
2022	434
2023	499
2024	570
Thereafter	8,103

At December 31, 2019, contractual maturities of our senior secured Credit Facility (in thousands) are as follows:



2020	$	12,800
2021	12,800
2022	12,800
2023	12,800
2024	12,800
Thereafter	1,183,600
Total	$	1,247,600

Asset Retirement Obligations (Tables)

12 Months Ended

Dec. 31, 2019

Asset Retirement Obligation Disclosure [Abstract]

Schedule of Changes in Asset Retirement Obligations

Changes in the asset retirement obligations (in thousands) during the years ended December 31, 2019 and 2018 are as follows:



	December 31, 2019		December 31, 2018
Beginning balance	$	18,413	$	19,032
Accretion	1,531		1,214
Additions and revisions of prior estimates	5,881		(319		)
Addition related to EPMH acquisition	—		2,733
EPMH measurement period adjustment	—		(2,131		)
Disposal related to sale of transloads	—		(2,116		)
Ending balance	$	25,825	$	18,413

Derivative Instruments (Tables)

12 Months Ended

Dec. 31, 2019

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Estimated Fair Values of Derivative Instruments



	December 31, 2019										December 31, 2018
	Maturity Date	Contract/Notional Amount			Carrying Amount			Fair Value			Maturity Date	Contract/Notional Amount			Carrying Amount			Fair Value
LIBOR⁽¹⁾ interest rate swap agreement	2020		$440	million	$	(2,768	)	$	(2,768	)	2020		$440	million	$	(1,475	)	$	(1,475	)
LIBOR⁽¹⁾interest rate swap agreement	2020		$200	million	$	(1,259	)	$	(1,259	)	2020		$200	million	$	(663	)	$	(663	)
LIBORinterest rate cap agreement		$	—		$	—		$	—		2019		$249	million	$	—		$	—

⁽¹⁾ Agreements fix the LIBOR interest rate base to 2.74%

Schedule of Effect of Derivatives Instruments on Combined Statements of Operations and Comprehensive Income



	2019			2018			2017
Deferred losses from derivatives in OCI, beginning of period	$	(1,621	)	$	(76	)	$	(32	)
(Loss) gain recognized in OCI from derivative instruments	(1,432		)	(1,622		)	(45		)
Loss reclassified from Accumulated OCI	—			77			1
Deferred losses from derivatives in OCI, end of period	$	(3,053	)	$	(1,621	)	$	(76	)

Equity-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Share-based Payment Arrangement [Abstract]

Schedule of Stock Options Activity

The following table summarizes the status of, and changes in, our stock option awards during the year ended December 31, 2019:



	Number of Shares		Weighted Average Exercise Price		Aggregate Intrinsic Value		Weighted Average Remaining Contractual Term in Years
Outstanding at December 31, 2018	901,996		$	28.52	$	18,566	4.8 years
Granted	—		—		—
Exercised	(10,000	)	12.87		—
Forfeited	—		—		—
Expired	(65,338	)	$	25.16	$	—
Outstanding at December 31, 2019	826,658		$	28.97	$	—	4.1 years
Exercisable at December 31, 2019	826,658		$	28.97	$	11,557	4.1 years

Schedule of Restricted Stock, Restricted Stock Unit and Performance Share Unit Awards Activity

The following table summarizes the status of, and changes in, our unvested restricted stock awards during the year ended December 31, 2019:



	Number of Shares		Grant Date Weighted Average Fair Value
Unvested, December 31, 2018	587,577		$	25.18
Granted	814,387		13.42
Vested	(306,806	)	26.18
Forfeited	(74,910	)	20.09
Unvested, December 31, 2019	1,020,248		$	15.86

The following table summarizes the status of, and changes in, our performance share unit awards during the year ended December 31, 2019:



	Number of Shares		Grant Date Weighted Average Fair Value
Unvested, December 31, 2018	838,188		$	39.44
Granted	607,130		15.58
Vested	(523,368	)	37.83
Forfeited/Cancelled	(83,228	)	25.60
Unvested, December 31, 2019	838,722		$	18.00

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2019

Commitments and Contingencies Disclosure [Abstract]

Schedule of Future Minimum Annual Commitments

Future Minimum Annual Commitments at December 31, 2019 (in thousands):



Year ending December 31,	Minimum Purchase Commitments
2020	$	14,512
2021	9,253
2022	6,900
2023	6,900
2024	3,593
Thereafter	2,490
Total future purchase commitments	$	43,648

Pension and Post-Retirement Benefits (Tables)

12 Months Ended

Dec. 31, 2019

Retirement Benefits [Abstract]

Schedule of Net Pension and Post-Retirement Benefit Plans

Net pension benefit cost (in thousands) consisted of the following for the years ended December 31, 2019, 2018 and 2017:



	Year Ended December 31,
	2019			2018			2017
Service cost	$	1,304		$	1,307		$	1,037
Interest cost	5,375			4,632			3,971
Expected return on plan assets	(6,171		)	(5,969		)	(5,265		)
Net amortization and deferral	1,648			2,526			1,773
Net pension benefit costs	$	2,156		$	2,496		$	1,516

Net post-retirement benefit cost (in thousands) consisted of the following for the years ended December 31, 2019, 2018 and 2017:



	Year Ended December 31,
	2019			2018		2017
Service cost	$	88		$	102	$	107
Interest cost	789			740		753
Expected return on plan assets	—			—		(1		)
Unrecognized net (gain)/loss	(29		)	—		—
Net post-retirement benefit costs	$	848		$	842	$	859

Schedule of Changes in Benefit Obligations and Plan Assets

The changes in benefit obligations and plan assets (in thousands), as well as the funded status (in thousands) of our pension and post-retirement plans at December 31, 2019 and 2018 are as follows:



	Pension Benefits						Post-retirement Benefits
	2019			2018			2019			2018
Benefit obligation at January 1,	$	138,900		$	122,052		$	21,570		$	22,771
Service cost	1,304			1,307			88			102
Interest cost	5,375			4,632			789			740
Actuarial (gain) loss	17,225			(10,263		)	206			(965		)
Benefits paid	(14,922		)	(8,202		)	(815		)	(1,499		)
Other⁽¹⁾	609			29,374			216			421
Benefit obligation at December 31,	$	148,491		$	138,900		$	22,054		$	21,570
Fair value of plan assets at January 1,	$	102,396		$	92,067		$	—		$	—
Actual return on plan assets	17,919			(6,204		)	—			—
Employer contributions	4,755			3,350			599			1,078
Benefits paid	(14,922		)	(8,202		)	(815		)	(1,499		)
Other⁽¹⁾	283			21,385			216			421
Fair value of plan assets at December 31,	$	110,431		$	102,396		$	—		$	—
Plan assets less than benefit obligations at December 31 recognized as liability for pension and other post-retirement benefits	$	(38,060	)	$	(36,504	)	$	(22,054	)	$	(21,570	)



(1	)	Includes opening pension benefit obligation and plan assets balances related to the May 1, 2018, EPMH acquisition and other adjustments.

Schedule of Estimated Future Pension and Post-Retirement Benefit Payments

Future estimated annual benefit payments (in thousands) for pension and post-retirement benefit obligations at December 31, 2019 are as follows:



	Benefits
			Post-retirement
	Pension		Before Medicare Subsidy		After Medicare Subsidy
2020	$	10,025	$	1,601	$	1,431
2021	9,221		1,669		1,502
2022	9,195		1,686		1,520
2023	9,208		1,659		1,492
2024	9,551		1,677		1,513
2025-2029	45,386		7,526		6,677

Schedule of Amounts in Accumulated Other Comprehensive Income Expected to be Recognized as Components of Net Periodic Benefit Cost

The amounts in accumulated other comprehensive income (loss) expected to be recognized as components of net periodic benefit cost (in thousands) during the following fiscal year are as follows:



	Benefits
	Pension		Post-retirement		Total
Net actuarial loss	$	2,532	$	—	$	2,532
Prior service cost	534		—		534
	$	3,066	$	—	$	3,066

Schedule of Weighted-Average Assumptions Used to Determine Benefit Obligations

The following weighted-average assumptions were used to determine our obligations under the plans:



	Pension Benefits				Post-retirement Benefits
	2019		2018		2019		2018
Discount rate	3.2	%	4.4	%	3.2	%	4.3	%
Long-term rate of compensation increase	3.0%-3.5%		3.0%-3.5%		N/A		N/A
Long-term rate of return on plan assets	6.3	%	6.25%-7.15%		N/A		N/A
Health care cost trend rate:
Pre-65 initial rate/ultimate rate	N/A		N/A		7.0%/4.5%		7.3%/4.5%
Pre-65 ultimate year	N/A		N/A		—		—
Post-65 initial rate/ultimate rate	N/A		N/A		7.5%/4.5%		8.0%/4.5%
Post-65 ultimate year	N/A		N/A		2026/2027		2026/2027

Schedule of Mortality Tables Used

Mortality tables used for pension benefits and post-retirement benefits plans are the following:



	Pension and Post-retirement Benefits
	2019	2018
Healthy Lives	Pri-2012 base mortality tables with generational mortality improvements using Scale MP-2019	RP-2014 mortality table, adjusted back to 2006 base rates, with generational mortality improvements using Scale MP-2018
Disabled Lives	Pri-2012 base mortality tables with generational mortality improvements using Scale MP-2019	RP-2014 disabled retiree mortality table, adjusted back to 2006 base rates, with generational mortality improvements using Scale MP-2018

Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates



	One-Percentage-Point
	Increase		Decrease
Effect on total of service and interest cost	$	100	$	(85	)
Effect on post-retirement benefit obligation	2,341		(2,010		)

Schedule of Major Investments Categories and Their Relative Percentage of the Fair Value to Total Plan Assets

The major investment categories and their relative percentage of the fair value of total plan assets as invested at December 31, 2019, and 2018 are as follows:



	Pension Benefits				Post-retirement Benefits⁽¹⁾
	2019		2018		2019		2018
Equity securities	52.1	%	42.1	%	—	%	—	%
Debt securities	46.6	%	55.5	%	—	%	—	%
Cash	1.3	%	2.4	%	—	%	—	%



(1	)	Retiree health benefits are paid by the Company as covered expenses are incurred.

Schedule of Fair Value of Pension Plan Assets by Asset Category

The fair values of the pension plan assets (in thousands) at December 31, 2019, by asset category, are as follows:



	Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	—	$	1,385	$	—	$	1,385
Mutual funds:
Diversified emerging markets	4,942		—		—		4,942
Foreign large blend	19,183		—		—		19,183
Large-cap blend	20,738		—		—		20,738
Mid-cap blend	8,416		—		—		8,416
Real estate	4,309		—		—		4,309
Fixed income securities:
Corporate notes and bonds	37,664		—		—		37,664
U.S. Treasuries	10,894		—		—		10,894
Mortgage-backed securities	—		2,496		—		2,496
Asset-backed securities	—		404		—		404
Net asset	$	106,146	$	4,285	$	—	$	110,431

The fair values of the pension plan assets (in thousands) at December 31, 2018, by asset category, are as follows:



	Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	—	$	2,449	$	—	$	2,449
Mutual funds:
Diversified emerging markets	6,638		—		—		6,638
Foreign large blend	11,689		—		—		11,689
Large-cap blend	14,226		—		—		14,226
Mid-cap blend	6,819		—		—		6,819
Small-cap blend	522		—		—		522
Real estate	3,192		—		—		3,192
Fixed income securities:
Corporate notes and bonds	43,745		—		—		43,745
U.S. Treasuries	8,486		—		—		8,486
Mortgage-backed securities	—		3,578		—		3,578
Asset-backed securities	—		1,052		—		1,052
Net asset	$	95,317	$	7,079	$	—	$	102,396

Schedule of Summary of Multiemployer Pension Plan

A summary of each multiemployer pension plan for which we participate is presented below:

Pension

Fund

EIN/ Pension

Plan No.

Pension Protection Act

Zone Status⁽¹⁾

FIP/RP Status

Pending/

Implemented

Company

Contributions

(in thousands)

Surcharge

Imposed

Expiration

Date of

CBA

2019

2018

2019

2018

2017

LIUNA

52-6074345/001

Red

Yes

385

573

223

Yes

5/31/2020

IUOE

36-6052390/001

Green

310

1,385

7/31/2022

CSSS⁽²⁾

36-6044243/001

Red

Yes


(1)	The Pension Protection Act of 2006 defines the zone status as follows: green—healthy, yellow—endangered, orange—seriously endangered and red—critical.

(2)

In 2011, we withdrew from the Central States, Southeast and Southwest Areas Pension Plan. The withdrawal liability of $1.0 million will be paid in monthly installments of $4,000 until 2031.

Leases (Tables)

12 Months Ended

Dec. 31, 2019

Leases [Abstract]

Schedule of Supplemental Balance Sheet Information

Supplemental balance sheet information related to leases (in thousands except for term and rate information) was as follows:



Leases	Classification	December 31, 2019
Assets
Operating	Operating lease right-of-use assets	$	53,098
Total leased assets		$	53,098
Liabilities
Current
Operating	Current portion of operating lease liabilities	$	53,587
Non-Current
Operating	Operating lease liabilities	117,964
Total lease liabilities		$	171,551



Lease Term and Discount Rate
Weighted average remaining lease term (years):
Operating leases	4.5 years

Weighted average discount rate:
Operating leases	5.7	%

Schedule of Components of Lease Expense and Supplemental Cash Flow Information

The components of lease expense included in our Consolidated Statements of Operations were as follows:



Lease Costs	Classification	Year Ended December 31, 2019
Operating lease costs (1)	Cost of Sales	$	88,966
Operating lease costs (2)	Selling, general, and administrative	3,993
Right-of-use asset impairment	Goodwill and other asset impairments	115,443
Total		$	208,402

(1) Includes short-term operating lease costs of $18.2 million for the year ended December 31, 2019.

(2) Includes short-term operating lease costs of $0.7 million for the year ended December 31, 2019.

Supplemental cash flow information related to leases was as follows:



	Year Ended December 31, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows for operating leases	$	74,740

Right-of-use assets obtained in exchange for new lease liabilities:
Operating leases	$	232,123

Schedule of Maturity of Lease Liabilities

Maturities of lease liabilities as of December 31, 2019:



Maturities of lease liabilities	Operating leases
2020	$	63,337
2021	44,276
2022	33,526
2023	22,380
2024	16,236
Thereafter	22,284
Total lease payments	$	202,039
Less: Interest	30,488
Total	$	171,551

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Schedule of Income Tax Benefit (Expense)

Income tax benefit (in thousands) consisted of the following for the years ended December 31, 2019, 2018 and 2017:



	Year ended December 31,
	2019			2018			2017
Current:
Federal	$	—		$	1,076		$	(10,754	)
State	(1,188		)	(2,496		)	(1,167		)
Foreign	(1,343		)	(518		)	—
	(2,531		)	(1,938		)	(11,921		)
Deferred:
Federal	90,457			25,578			22,641
State	11,225			5,492			(2,040		)
Foreign	—			—			—
	101,682			31,070			20,601
Income tax benefit	$	99,151		$	29,132		$	8,680

Schedule of Effective Income Tax Rate on Pretax Earnings



	Year ended December 31,
	2019			2018			2017
Income tax (expense) benefit computed at U.S. federal statutory rate	$	90,070		$	48,290		$	(47,784	)
Decrease (increase) resulting from:
Statutory depletion	4,679			12,090			20,259
Goodwill impairment	—			(29,157		)	—
Prior year tax return reconciliation	3,121			530			219
State income taxes, net of federal benefit	9,486			2,592			(2,267		)
Adjustment to deferred taxes from the Tax Act rate reduction	—			—			35,772
Equity compensation	(6,440		)	(653		)	2,602
Other, net	(1,765		)	(4,560		)	(121		)
Income tax benefit	$	99,151		$	29,132		$	8,680

Schedule of Tax Effects on Deferred Tax Assets and Liabilities

The tax effects of the types of temporary differences and carry forwards that gave rise to deferred tax assets and liabilities (in thousands) at December 31, 2019 and 2018 consisted of the following:



	December 31,
	2019			2018
Gross deferred tax assets:
Net operating loss carry forward and state tax credits	$	32,173		$	11,089
Pension and post-retirement benefit costs	13,976			13,303
Alternative minimum tax credit carry forward	7,895			15,971
Property, plant and equipment	7,179			5,474
Accrued expenses	15,336			27,025
Inventories	6,507			774
Third-party products liability	236			231
Stock-based compensation expense	2,390			8,199
Note payable	109			3,724
Interest expense limitation	22,324			—
Lease obligation liability	29,604			—
Other	5,191			8,116
Total deferred tax assets	142,920			93,906
Gross deferred tax liabilities:
Land and mineral property basis difference	(124,182		)	(165,002		)
Fixed assets and depreciation	(44,314		)	(55,596		)
Intangibles	(12,541		)	(10,346		)
Other	(468		)	(201		)
Total deferred tax liabilities	(181,505		)	(231,145		)
Net deferred tax liabilities	$	(38,585	)	$	(137,239	)

Revenue (Tables)

12 Months Ended

Dec. 31, 2019

Revenue from Contract with Customer [Abstract]

Schedule of Sales by Major Source

The following table reflects our sales disaggregated by major source for the year ended December 31, 2019 (in thousands):



	Year Ended December 31, 2019						Year Ended December 31, 2018
Category	Oil & Gas Proppants		Industrial & Specialty Products		Total Sales		Oil & Gas Proppants		Industrial & Specialty Products		Total Sales
Product	$	704,516	$	463,956	$	1,168,472	$	888,509	$	394,290	$	1,282,799
Service	306,005		—		306,005		294,482		17		294,499
Total Sales	$	1,010,521	$	463,956	$	1,474,477	$	1,182,991	$	394,307	$	1,577,298

Schedule of Changes in Contract Assets and Liabilities



	Unbilled Receivables
	December 31, 2019			December 31, 2018
Beginning Balance	$	90		$	5,245
Reclassifications to billed receivables	(3,983		)	(11,157		)
Revenues recognized in excess of period billings	4,037			6,002
Ending Balance	$	144		$	90



	Deferred Revenue
	December 31, 2019			December 31, 2018
Beginning Balance	$	113,319		$	118,414
Revenues recognized from balances held at the beginning of the period	(65,225		)	(33,381		)
Revenues deferred from period collections on unfulfilled performance obligations	12,225			31,625
Revenues recognized from period collections	(9,685		)	(3,339		)
Ending Balance	$	50,634		$	113,319

Segment Reporting (Tables)

12 Months Ended

Dec. 31, 2019

Segment Reporting [Abstract]

Schedule of Sales and Segment Contribution Margin for Reporting Segments and Operating Results



	Year Ended December 31,
	2019			2018			2017
Sales:
Oil & Gas Proppants	$	1,010,521		$	1,182,991		$	1,020,365
Industrial & Specialty Products	463,956			394,307			220,486
Total sales	1,474,477			1,577,298			1,240,851
Segment contribution margin:
Oil & Gas Proppants	248,594			357,846			301,972
Industrial & Specialty Products	178,215			155,084			88,781
Total segment contribution margin	426,809			512,930			390,753
Operating activities excluded from segment cost of sales⁽¹⁾	(85,625		)	(98,761		)	(16,722		)
Selling, general and administrative	(150,848		)	(146,971		)	(107,056		)
Depreciation, depletion and amortization	(179,444		)	(148,832		)	(97,233		)
Goodwill and other asset impairments	(363,847		)	(281,899		)	—
Interest expense	(95,472		)	(70,564		)	(31,342		)
Other income (expense), net, including interest income	19,519			4,144			(1,874		)
Income tax benefit	99,151			29,132			8,680
Net (loss) income	$	(329,757	)	$	(200,821	)	$	145,206
Less: Net loss attributable to non-controlling interest	(675		)	(13		)	—
Net (loss) income attributable to U.S. Silica Holdings, Inc.	$	(329,082	)	$	(200,808	)	$	145,206



(1)	2019 and 2018 mainly driven by plant capacity expansion expenses, amortization of purchase accounting inventory fair value step-up, and facility closure costs.

Unaudited Supplementary Data (Tables)

12 Months Ended

Dec. 31, 2019

Quarterly Financial Information Disclosure [Abstract]

Schedule of Unaudited Quarterly Information



	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
2019	(Unaudited)
Sales:
Product	$	296,860		$	303,041		$	287,977		$	280,594
Service	81,890			91,813			73,837			58,465
Cost of sales (excluding depreciation, depletion and amortization):
Product	234,916			225,473			226,797			212,905
Service	62,622			68,687			56,836			45,057
Operating expenses:
Selling, general and administrative	34,656			38,659			40,208			37,325
Depreciation, depletion and amortization	44,600			44,899			47,126			42,819
Goodwill and other asset impairments	—			—			130			363,717
Total operating expenses	79,256			83,558			87,464			443,861
Operating (loss) income	1,956			17,136			(9,283		)	(362,764		)
Other (expense) income:
Interest expense	(23,978		)	(23,765		)	(24,733		)	(22,996		)
Other income (expense), net, including interest income	722			15,074			3,280			443
Total other expense	(23,256		)	(8,691		)	(21,453		)	(22,553		)
(Loss) income before income taxes	(21,300		)	8,445			(30,736		)	(385,317		)
Income tax benefit	1,972			(2,384		)	7,671			91,892
Net (loss) income	(19,328		)	6,061			(23,065		)	(293,425		)
Less: Net loss attributable to non-controlling interest	(4		)	(89		)	(28		)	(554		)
Net (loss) income attributable to U.S. Silica Holdings, Inc.	$	(19,324	)	$	6,150		$	(23,037	)	$	(292,871	)

(Loss) earnings per share, basic	$	(0.26	)	$	0.08		$	(0.31	)	$	(4.00	)
(Loss) earnings per share, diluted	$	(0.26	)	$	0.08		$	(0.31	)	$	(4.00	)
Weighted average shares outstanding, basic	73,040			73,301			73,328			73,343
Weighted average shares outstanding, diluted	73,040			73,505			73,328			73,343
Dividends declared per share	$	0.06		$	0.06		$	0.06		$	0.06

	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
2018	(Unaudited)
Sales:
Product	$	294,788		$	345,957		$	348,635		$	293,419
Service	74,525			81,476			74,537			63,961



Cost of sales (excluding depreciation, depletion and amortization):
Product	207,239			236,236			270,370			241,624
Service	53,671			56,609			51,966			45,414
Operating expenses:
Selling, general and administrative	34,591			42,232			37,980			32,168
Depreciation, depletion and amortization	28,592			36,563			37,150			46,527
Goodwill and other asset impairments	—			16,184			—			265,715
Total operating expenses	63,183			94,979			75,130			344,410
Operating (loss) income	45,220			39,609			25,706			(274,068		)
Other (expense) income:
Interest expense	(7,070		)	(20,214		)	(21,999		)	(21,281		)
Other income (expense), net, including interest income	665			1,081			1,062			1,336
Total other expense	(6,405		)	(19,133		)	(20,937		)	(19,945		)
(Loss) income before income taxes	38,815			20,476			4,769			(294,013		)
Income tax benefit	(7,521		)	(2,832		)	1,547			37,938
Net (loss) income	31,294			17,644			6,316			(256,075		)
Less: Net loss attributable to non-controlling interest	—			—			—			(13		)
Net (loss) income attributable to U.S. Silica Holdings, Inc.	$	31,294		$	17,644		$	6,316		$	(256,062	)

Earnings (loss) per share, basic	$	0.39		$	0.23		$	0.08		$	(3.44	)
Earnings (loss) per share, diluted	$	0.39		$	0.22		$	0.08		$	(3.44	)
Weighted average shares, basic	79,496			77,784			77,365			74,485
Weighted average shares, diluted	80,309			78,480			77,859			74,485
Dividends declared per share	$	0.06		$	0.06		$	0.06		$	0.06

Parent Company Financials (Tables)

12 Months Ended

Dec. 31, 2019

Condensed Financial Information Disclosure [Abstract]

Condensed Balance Sheets

U.S. SILICA HOLDINGS, INC.

(PARENT COMPANY ONLY)

CONDENSED BALANCE SHEETS



	December 31,
	2019			2018
	(in thousands)
ASSETS
Current Assets:
Cash and cash equivalents	$	51,849		$	107,151
Due from affiliates	138,988			100,094
Total current assets	190,837			207,245
Investment in subsidiaries	530,830			850,099
Total assets	$	721,667		$	1,057,344
LIABILITIES AND STOCKHOLDERS’ EQUITY
Current Liabilities:
Accrued expenses and other current liabilities	$	129		$	217
Dividends payable	4,958			4,823
Total current liabilities	5,087			5,040
Total liabilities	5,087			5,040
Stockholders’ Equity:
Preferred stock	—			—
Common stock	823			818
Additional paid-in capital	1,185,116			1,169,383
Retained (deficit) earnings	(279,956		)	67,854
Treasury stock, at cost	(180,912		)	(178,215		)
Accumulated other comprehensive loss	(19,854		)	(15,020		)
Total U.S. Silica Holdings, Inc. stockholders’ equity	705,217			1,044,820
Non-controlling interest	11,363			7,484
Total stockholders' equity	716,580			1,052,304
Total liabilities and stockholders’ equity	$	721,667		$	1,057,344

Condensed Statements of Operations and Comprehensive Income (Loss)

U.S. SILICA HOLDINGS, INC.

(PARENT COMPANY ONLY)

CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS)



	Year ended December 31,
	2019			2018			2017
	(in thousands)
Sales	$	—		$	—		$	—
Cost of sales	—			—			—
Operating expenses
Selling, general and administrative	253			254			252
Total operating expenses	253			254			252
Operating loss	(253		)	(254		)	(252		)
Other income (expense)
Interest income	1,440			2,784			3,854
Total other income	1,440			2,784			3,854
Income before income taxes and equity in net earnings of subsidiaries	1,187			2,530			3,602
Income tax expense	(327		)	(696		)	(1,453		)
Income before equity in net earnings of subsidiaries	860			1,834			2,149
Equity in earnings of subsidiaries, net of tax	(330,617		)	(202,655		)	143,057
Net (loss) income	(329,757		)	(200,821		)	145,206
Less: Net loss attributable to non-controlling interest	(675		)	(13		)	—
Net (loss) income attributable to U.S. Silica Holdings, Inc.	(329,082		)	(200,808		)	145,206

Net (loss) income	(329,757		)	(200,821		)	145,206
Other comprehensive (loss) income
Unrealized loss on derivatives (net of tax of $(456),$(470), and $(27) for 2019, 2018, and 2017, respectively)	(1,432		)	(1,545		)	(44		)
Foreign currency translation adjustment (net of tax of $(60), $(196), and $2 for 2019, 2018 and 2017, respectively)	(188		)	(614		)	(6		)
Pension and other post-retirement benefits liability adjustment (net of tax of $(1,024), $339, and $1,205 for 2019, 2018 and 2017, respectively)	(3,214		)	1,065			2,000
Comprehensive (loss) income	(334,591		)	(201,915		)	147,156
Less: Comprehensive loss attributable to non-controlling interest	(675		)	(13		)	—
Comprehensive (loss) income attributable to U.S. Silica Holdings, Inc.	(333,916		)	(201,902		)	147,156

Condensed Statements of Stockholders' Equity

U.S. SILICA HOLDINGS, INC.

(PARENT COMPANY ONLY)

CONDENSED STATEMENTS OF STOCKHOLDERS' EQUITY



(amounts in thousands)	Par Value		Treasury Stock			Additional Paid-In Capital			Retained Earnings - Present			Accumulated Other Comprehensive Income (Loss)			Total U.S. Silica, Inc. Stockholders' Equity			Non-controlling Interest			Total Stockholders’ Equity
Balance at January 1, 2017	$	811	$	(3,869	)	$	1,129,051		$	163,173		$	(15,876	)	$	1,273,290		$	—		$	1,273,290
Net income	—		—			—			145,206			—			145,206			—			145,206
Unrealized loss on derivatives	—		—			—			—			(44		)	(44		)	—			(44		)
Foreign currency translation adjustment	—		—			—			—			(6		)	(6		)	—			(6		)
Pension and post-retirement liability	—		—			—			—			2,000			2,000			—			2,000
Cash dividend declared ($0.25 per share)	—		—			—			(20,387		)	—			(20,387		)	—			(20,387		)
Common stock-based compensation plans activity:
Equity-based compensation	—		—			25,050			—			—			25,050			—			25,050
Proceeds from options exercised	—		1,190			(392		)	—			—			798			—			798
Issuance of restricted stock	—		1,859			(1,859		)	—			—			—			—			—
Shares withheld for employee taxes related to vested restricted stock and stock units	1		386			(4,766		)	—			—			(4,379		)	—			(4,379		)
Repurchase of common stock			(25,022		)										(25,022		)	—			(25,022		)
Balance at December 31, 2017	$	812	$	(25,456	)	$	1,147,084		$	287,992		$	(13,926	)	$	1,396,506		$	—		$	1,396,506
Net loss	—		—			—			(200,808		)	—			(200,808		)	(13		)	(200,821		)
Unrealized loss on derivatives	—		—			—			—			(1,545		)	(1,545		)	—			(1,545		)
Foreign currency translation adjustment	—		—			—			—			(614		)	(614		)	—			(614		)
Pension and post-retirement liability	—		—			—			—			1,065			1,065			—			1,065
Cash dividend declared ($0.25 per share)	—		—			—			(19,330		)	—			(19,330		)	—			(19,330		)
Contributions from non-controlling interest	—		—			—			—			—			—			7,497			7,497
Common stock-based compensation plans activity:
Equity-based compensation	—		—			22,337			—			—			22,337			—			22,337
Proceeds from options exercised	—		93			(32		)	—			—			61			—			61
Shares withheld for employee taxes related to vested restricted stock and stock units	6		(4,383		)	(6		)	—			—			(4,383		)	—			(4,383		)
Repurchase of common stock	—		(148,469		)	—			—			—			(148,469		)	—			(148,469		)
Balance at December 31, 2018	$	818	$	(178,215	)	$	1,169,383		$	67,854		$	(15,020	)	$	1,044,820		$	7,484		$	1,052,304
Net loss	—		—			—			(329,082		)	—			(329,082		)	(675		)	(329,757		)
Unrealized loss on derivatives	—		—			—			—			(1,432		)	(1,432		)	—			(1,432		)
Foreign currency translation adjustment	—		—			—			—			(188		)	(188		)	—			(188		)
Pension and post-retirement liability	—		—			—			—			(3,214		)	(3,214		)	—			(3,214		)
Cash dividend declared ($0.25 per share)	—		—			—			(18,728		)	—			(18,728		)	—			(18,728		)
Contributions from non-controlling interest	—		—			—			—			—			—			4,554			4,554
Common stock-based compensation plans activity:



Equity-based compensation	—		—			15,906			—			—			15,906			—		15,906
Proceeds from options exercised	—		296			(168		)	—			—			128			—		128
Shares withheld for employee taxes related to vested restricted stock and stock units	5		(2,993		)	(5		)	—			—			(2,993		)	—		(2,993		)
Balance at December 31, 2019	$	823	$	(180,912	)	$	1,185,116		$	(279,956	)	$	(19,854	)	$	705,217		$	11,363	$	716,580

Condensed Statements of Cash Flows

U.S. SILICA HOLDINGS, INC.

(PARENT COMPANY ONLY)

CONDENSED STATEMENTS OF CASH FLOWS



	Year ended December 31,
	2019			2018			2017
	(in thousands)
Operating activities:
Net (loss) income	$	(329,757	)	$	(200,821	)	$	145,206
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Undistributed loss (income) from equity method investment, net	330,617			202,655			(143,057		)
Changes in assets and liabilities, net of effects of acquisitions:
Accounts payable and accrued liabilities	(88		)	(295		)	48
Net cash provided by operating activities	772			1,539			2,197
Investing activities:
Investment in subsidiary	—			—			(143,654		)
Net cash used in investing activities	—			—			(143,654		)
Financing activities:
Dividends paid	(18,592		)	(19,912		)	(20,377		)
Repurchase of common stock	—			(148,469		)	(25,022		)
Proceeds from options exercised	128			61			798
Tax payments related to shares withheld for vested restricted stock and stock units	(2,993		)	(4,383		)	(4,379		)
Contributions from non-controlling interest	4,554			7,497			—
Net financing activities with subsidiaries	(39,171		)	40,171			(113,294		)
Net cash used in financing activities	(56,074		)	(125,035		)	(162,274		)
Net decrease in cash and cash equivalents	(55,302		)	(123,496		)	(303,731		)
Cash and cash equivalents, beginning of period	107,151			230,647			534,378
Cash and cash equivalents, end of period	$	51,849		$	107,151		$	230,647
Supplemental cash flow information:
Cash (received) paid during the period for:
Interest	$	(1,440	)	$	(2,784	)	$	(3,853	)

Impairments (Tables)

12 Months Ended

Dec. 31, 2019

Disclosure Text Block Supplement [Abstract]

Schedule of Asset Impairment Charges

, we have recorded impairment charges (in thousands) for the years ended December 31, 2019 and 2018 for the following assets:



Description	December 31, 2019		December 31, 2018
Inventories, net	$	4,100	$	3,316
Property, plant and mine development, net	243,064		109,938
Operating lease right-of-use assets	115,443		—
Goodwill	—		164,167
Intangible assets, net	1,240		4,478
Total	$	363,847	$	281,899

Organization (Details) $ in Thousands		12 Months Ended
Organization (Details) $ in Thousands	May 01, 2018 USD ($)	Dec. 31, 2019 USD ($) Segment	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Organization And Nature Of Business
Number of business segments \| Segment		2
Consideration paid, net of cash acquired		$ 0	$ 743,249	$ 119,801
EPMH
Organization And Nature Of Business
Consideration paid, net of cash acquired	$ 743,200
Cash acquired	19,100
Net working capital post-closing adjustments	$ 500

Summary of Significant Accounting Policies (Details) - USD ($)	3 Months Ended			12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Water rights intangibles acquired in VIE				$ 3,932,000	$ 10,046,000	$ 3,586,000
Percent or reporting unit fair value less than carrying value				50.00%
Consolidated sales				$ 1,474,477,000	1,577,298,000	1,240,851,000
Amortization of debt issuance costs and discounts included in interest expense				5,600,000	4,000,000.0	$ 1,400,000
Self-insurance reserves	$ 6,600,000	$ 5,400,000		6,600,000	5,400,000
Self-insurance reserves classified as current	4,100,000	2,600,000		4,100,000	2,600,000
Goodwill impairment				0	164,167,000
Operating lease right-of-use assets	53,098,000			53,098,000
Impairment recognized on operating lease right-of-use assets	115,400,000			115,443,000	0
Lease liabilities	171,551,000			171,551,000
ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets							$ 223,000,000.0
Lease liabilities							$ 222,700,000
Other income (expense) net, including interest income
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net realized gain (loss) on foreign currency translation				$ 200,000	$ 600,000
Restricted Stock and Restricted Stock Units
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Vesting period for awards of equity instruments				3 years
Performance Share Units
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Vesting period for awards of equity instruments				3 years
Performance Share Units \| Certain Employees
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Vesting period for awards of equity instruments					3 years
Intellectual property
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful live of finite-lived intangible assets				15 years
Customer relationships
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful live of finite-lived intangible assets				20 years
Oil & Gas Sand
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Goodwill impairment		$ 164,200,000
Buildings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful lives of property, plant and mine equipment				15 years
Land improvements
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful lives of property, plant and mine equipment				10 years
Furniture and fixtures
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful lives of property, plant and mine equipment				8 years
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Self-insurance retention amount				$ 100,000
Minimum \| Stock options excluded
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Vesting period for awards of equity instruments				3 years
Minimum \| Supply Agreement
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred revenue, average initial contract term				one
Minimum \| Customer relationships
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful live of finite-lived intangible assets				13 years
Minimum \| Machinery and equipment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful lives of property, plant and mine equipment				3 years
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Self-insurance retention amount				$ 500,000
Maximum \| Stock options excluded
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Vesting period for awards of equity instruments				4 years
Maximum \| Supply Agreement
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred revenue, average initial contract term				fifteen
Maximum \| Customer relationships
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful live of finite-lived intangible assets				15 years
Maximum \| Machinery and equipment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful lives of property, plant and mine equipment				10 years
Variable Interest Entity, Primary Beneficiary
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Equity ownership percentage acquired in VIE			50.00%
Payments to acquire interest in VIE			$ 3,200,000
Maximum capital contribution to VIE			7,000,000.0
VIE assets	18,300,000			$ 18,300,000
VIE liabilities	$ 400,000			400,000
Capital contributions paid to acquire interest in VIE				$ 400,000	$ 7,000,000.0
Variable Interest Entity, Primary Beneficiary \| Water rights
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Water rights intangibles acquired in VIE			$ 700,000

Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator:
Net (loss) income attributable to U.S. Silica Holdings, Inc.	$ (292,871)	$ (23,037)	$ 6,150	$ (19,324)	$ (256,062)	$ 6,316	$ 17,644	$ 31,294	$ (329,082)	$ (200,808)	$ 145,206
Denominator:
Weighted average shares outstanding, basic (in shares)	73,343	73,328	73,301	73,040	74,485	77,365	77,784	79,496	73,253	76,453	81,051
Diluted effect of stock awards (shares)									0	0	909
Weighted average shares outstanding assuming dilution (shares)									73,253	76,453	81,960
(Loss) earnings per share attributable to U.S. Silica Holdings, Inc.:
Basic (loss) earnings per share (in dollars per share)	$ (4.00)	$ (0.31)	$ 0.08	$ (0.26)	$ (3.44)	$ 0.08	$ 0.23	$ 0.39	$ (4.49)	$ (2.63)	$ 1.79
Diluted (loss) earnings per share (in dollars per share)	$ (4.00)	$ (0.31)	$ 0.08	$ (0.26)	$ (3.44)	$ 0.08	$ 0.22	$ 0.39	$ (4.49)	$ (2.63)	$ 1.77

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Earnings Per Share - Antidilutive Securities Excluded From Calculation of Diluted Earnings Per Share (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average outstanding stock options and restricted stock awards excluded (shares)	68	443
Stock options excluded
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average outstanding stock options and restricted stock awards excluded (shares)	711	574	195
Restricted stock and performance share units awards excluded
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average outstanding stock options and restricted stock awards excluded (shares)	1,298	155	305

Capital Structure and Accumulated Other Comprehensive Income (Loss) - Additional Information (Details) - USD ($)	7 Months Ended
	Dec. 31, 2018	Dec. 31, 2019	May 31, 2018
Capital Structure And Accumulated Comprehensive Income (Loss)
Common stock authorized (shares)	500,000,000	500,000,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock issued (shares)	81,811,977	82,601,926
Common stock outstanding (shares)	73,148,853	73,601,950
Preferred stock authorized (shares)	10,000,000	10,000,000
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock issued (shares)	0	0
May 2018 Share Repurchase Program
Capital Structure And Accumulated Comprehensive Income (Loss)
Share repurchase program authorized amount			$ 200,000,000
Repurchase of common stock (shares)	5,036,139
Average price per common share of repurchase common stock (in dollars per share)	$ 14.59
Remaining authorized repurchase amount		$ 126,500,000

Capital Structure and Accumulated Other Comprehensive Income (Loss) - Declared Quarterly Cash Dividends (Details) - $ / shares	Nov. 12, 2019	Jul. 18, 2019	May 13, 2019	Feb. 15, 2019
Equity [Abstract]
Dividends per Common Share (in dollars per share)	$ 0.0625	$ 0.0625	$ 0.0625	$ 0.0625

Capital Structure and Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Loss (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	$ 1,044,820
Other comprehensive loss before reclassifications	(6,070)
Amounts reclassed from accumulated other comprehensive loss	1,236
Ending Balance	705,217
Unrealized loss on cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(1,621)
Other comprehensive loss before reclassifications	(1,432)
Amounts reclassed from accumulated other comprehensive loss	0
Ending Balance	(3,053)
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(620)
Other comprehensive loss before reclassifications	(188)
Amounts reclassed from accumulated other comprehensive loss	0
Ending Balance	(808)
Pension and other post-retirement benefits liability
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(12,779)
Other comprehensive loss before reclassifications	(4,450)
Amounts reclassed from accumulated other comprehensive loss	1,236
Ending Balance	(15,993)
Total
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(15,020)
Ending Balance	$ (19,854)

Business Combinations - Additional Information (Details) - USD ($) $ in Thousands				7 Months Ended	8 Months Ended	12 Months Ended
	May 01, 2018	Aug. 16, 2017	Apr. 01, 2017	Mar. 31, 2018	Aug. 16, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jun. 30, 2019	Sep. 30, 2018
Business Acquisition [Line Items]
Consideration paid, net of cash acquired						$ 0	$ 743,249	$ 119,801
Goodwill						273,524	261,340	272,079
Total cash consideration for pre-existing contracted asset sale						$ 118,357	339,815	368,479
EPMH
Business Acquisition [Line Items]
Consideration paid, net of cash acquired	$ 743,200
Cash acquired	19,100
Net working capital post-closing adjustments	$ 500
Revenues from acquiree included in Income Statement							158,800
Net loss from acquiree included in Income Statement							600
Non-recurring transaction costs attributable to business combination excluded from pro-forma information							179,220	(116,899)
Goodwill							150,628		$ 162,812
EPMH \| Acquisition-related Costs
Business Acquisition [Line Items]
Non-recurring transaction costs attributable to business combination excluded from pro-forma information							15,200
EPMH \| Selling, general, and administrative
Business Acquisition [Line Items]
Acquisition-related costs							$ 13,600
White Armor
Business Acquisition [Line Items]
Cash consideration paid			$ 18,600
Goodwill			3,900
Identifiable intangible assets			12,800
Other net assets			$ 1,900
White Armor \| Selling, general, and administrative
Business Acquisition [Line Items]
Acquisition-related costs								200
MS Sand
Business Acquisition [Line Items]
Consideration paid, net of cash acquired		$ 95,400
Cash acquired		2,200
Net working capital post-closing adjustments		(500)
Non-recurring transaction costs attributable to business combination excluded from pro-forma information								(143,604)
Goodwill								$ 22,522		$ 25,322
Additional consideration paid		$ 6,100
Total cash consideration for pre-existing contracted asset sale					$ 101,000
MS Sand \| Selling, general, and administrative
Business Acquisition [Line Items]
Acquisition-related costs				$ 1,000

Business Combinations - Purchase Price Allocation (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
	Sep. 30, 2018	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	May 01, 2018	Dec. 31, 2017
Purchase Price
Goodwill			$ 273,524	$ 261,340		$ 272,079
EPMH
Purchase Price
Accounts receivable, net		$ 43,305		43,305
Inventories		86,112		86,112
Property, plant and mine development		146,558		148,495
Mineral rights		408,889		419,469
Identifiable intangible assets - finite lived		8,770		10,270	$ 8,770
Identifiable intangible assets - indefinite lived		36,800		38,050
Prepaids and deposits		1,827		2,072
Other non-current assets		7,474		7,474
Goodwill		162,812		150,628
Total assets acquired		902,547		905,875
Accounts payable		13,435		13,435
Accrued expenses and other current liabilities		10,304		10,304
Deferred tax liabilities		119,483		122,811
Other long term liabilities		16,076		16,076
Total liabilities assumed		159,298		162,626
Net assets acquired		743,249		743,249
Measurement Period Adjustments
Accounts receivable, net		0
Inventories		0
Property, plant and mine development		(1,937)
Mineral rights		(10,580)
Identifiable intangible assets - finite lived		(1,500)
Identifiable intangible assets - indefinite lived		(1,250)
Prepaids and deposits		(245)
Other assets		0
Goodwill		12,184	$ 12,184
Total assets acquired		(3,328)
Accounts payable		0
Accrued expenses and other current liabilities		0
Deferred tax liabilities		(3,328)
Long term obligations		0
Total liabilities assumed		(3,328)
Net assets acquired		$ 0
MS Sand
Purchase Price
Accounts receivable, net	$ 11,201					11,201
Inventories	8,067					8,067
Other current assets	362					362
Assets held for sale	9,453					9,453
Property, plant and mine development	27,458					27,458
Mineral rights	23,500					26,300
Identifiable intangible assets - finite lived	1,840					1,840
Other non-current assets	1,136					1,136
Goodwill	25,322					22,522
Total assets acquired	108,339					108,339
Accounts payable and accrued expenses	3,761					3,761
Unfavorable leasehold positions	2,237					2,237
Notes Payable	866					866
Asset retirement obligations	474					474
Other long term liabilities	0					0
Total liabilities assumed	7,338					7,338
Net assets acquired	101,001					$ 101,001
Measurement Period Adjustments
Accounts receivable, net	0
Inventories	0
Other current assets	0
Assets held for sale	0
Property, plant and mine development	0
Mineral rights	(2,800)
Identifiable intangible assets - finite lived	0
Other assets	0
Goodwill	2,800			$ 2,800
Total assets acquired	0
Accounts payable and accrued expenses	0
Unfavorable leasehold positions	0
Notes Payable	0
Other long term liabilities	0
Asset retirement obligations	0
Total liabilities assumed	0
Net assets acquired	$ 0

Business Combinations - Intangible Assets Acquired (Details) - USD ($) $ in Thousands	May 01, 2018	Aug. 16, 2017	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
EPMH
Business Acquisition [Line Items]
Identifiable intangible assets - finite lived, Approximate Fair Value	$ 8,770		$ 8,770	$ 10,270
Identifiable intangible assets - indefinite lived, Approximate Fair Value			$ 36,800	$ 38,050
EPMH \| Trade names
Business Acquisition [Line Items]
Identifiable intangible assets - indefinite lived, Approximate Fair Value	36,800
EPMH \| Intellectual property
Business Acquisition [Line Items]
Identifiable intangible assets - finite lived, Approximate Fair Value	$ 1,400
Identifiable intangible assets - finite lived, Estimated Useful Life (in years)	15 years
EPMH \| Customer relationships
Business Acquisition [Line Items]
Identifiable intangible assets - finite lived, Approximate Fair Value	$ 7,370
Identifiable intangible assets - finite lived, Estimated Useful Life (in years)	15 years
MS Sand
Business Acquisition [Line Items]
Identifiable intangible assets - finite lived, Approximate Fair Value					$ 1,840	$ 1,840
MS Sand \| Customer relationships
Business Acquisition [Line Items]
Identifiable intangible assets - finite lived, Approximate Fair Value		$ 1,840
Identifiable intangible assets - finite lived, Estimated Useful Life (in years)		15 years

Business Combinations - Pro Forma Information (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
EPMH
Business Acquisition [Line Items]
Sales	$ 1,659,775	$ 1,454,070
Net (loss) income	$ (179,220)	$ 116,899
Basic (loss) earnings per share (in dollars per share)	$ (2.34)	$ 1.44
Diluted (loss) earnings per share (in dollars per share)	$ (2.34)	$ 1.43
MS Sand
Business Acquisition [Line Items]
Sales		$ 1,287,202
Net (loss) income		$ 143,604
Basic (loss) earnings per share (in dollars per share)		$ 1.77
Diluted (loss) earnings per share (in dollars per share)		$ 1.75

Accounts Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Receivables [Abstract]
Trade receivables	$ 178,182	$ 198,435
Less: Allowance for doubtful accounts	(8,984)	(6,751)
Net trade receivables	169,198	191,684
Other receivables	13,040	23,802
Total accounts receivable	182,238	215,486
Refundable alternative minimum tax credits	$ 8,100	$ 16,000

Accounts Receivable - Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for Doubtful Accounts Receivable Roll Forward
Beginning balance	$ 6,751	$ 7,100
Bad debt provision	3,466	315	$ 1,529
Write-offs	(1,233)	(664)
Ending balance	$ 8,984	$ 6,751	$ 7,100

Accounts Receivable - Additional Information (Details) - Product Concentration Risk	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Sales \| Ten Largest Customers
Concentration Risk [Line Items]
Concentration risk percentage	43.00%	48.00%	58.00%
Sales \| Customer One
Concentration Risk [Line Items]
Concentration risk percentage	11.00%	15.00%	15.00%
Sales \| Customer Two
Concentration Risk [Line Items]
Concentration risk percentage			12.00%
Trade Accounts Receivables \| Customer One
Concentration Risk [Line Items]
Concentration risk percentage	12.00%	18.00%

Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Supplies	$ 47,277	$ 41,453
Raw materials and work in process	41,167	68,474
Finished goods	35,988	52,160
Total inventories	$ 124,432	$ 162,087

Property, Plant and Mine Development (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment
Property, plant and mine development, gross	$ 2,224,197	$ 2,326,126
Accumulated depletion, depreciation, amortization and impairment charges	(706,610)	(499,823)
Total property, plant and mine development, net	1,517,587	1,826,303
Mining property and mine development
Property, Plant and Equipment
Property, plant and mine development, gross	794,899	995,759
Asset retirement cost
Property, Plant and Equipment
Property, plant and mine development, gross	18,260	12,732
Land
Property, Plant and Equipment
Property, plant and mine development, gross	57,082	55,502
Land improvements
Property, Plant and Equipment
Property, plant and mine development, gross	73,203	67,729
Buildings
Property, Plant and Equipment
Property, plant and mine development, gross	69,112	64,515
Machinery and equipment
Property, Plant and Equipment
Property, plant and mine development, gross	1,152,898	958,357
Furniture and fixtures
Property, Plant and Equipment
Property, plant and mine development, gross	4,068	3,599
Construction-in-progress
Property, Plant and Equipment
Property, plant and mine development, gross	$ 54,675	$ 167,933

Property, Plant and Mine Development - Additional Information (Details)		3 Months Ended	12 Months Ended
	Mar. 21, 2018 USD ($) transload	Dec. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)
Property, Plant and Equipment
Depreciation expense			$ 168,600,000	$ 139,100,000
Aggregate cost of machinery and equipment under capital lease		$ 2,224,197,000	2,224,197,000	2,326,126,000
Impairment of property, plant and equipment			243,064,000	109,938,000
Gain on sale of transload facilities			(1,573,000)	5,170,000	$ (415,000)
Consideration received allocated to asset retirement obligations liabilities of transload facilities			0	2,116,000
Disposal Group, Held-for-sale, Not Discontinued Operations \| Land
Property, Plant and Equipment
Impairment recognized on assets held for sale			0
Disposal Group, Held-for-sale, Not Discontinued Operations \| Land \| Prepaid expenses and other current assets
Property, Plant and Equipment
Assets held for sale		100,000	100,000			$ 1,300,000
Depreciation adjustment on assets held for sale			0
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Land \| Prepaid expenses and other current assets
Property, Plant and Equipment
Gain on sale of assets		600,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Permian, Eagle Ford, and Appalachian Basins \| CIG Logistics
Property, Plant and Equipment
Number of transload facilities sold \| transload	3
Total consideration received on sale of transload facilities	$ 86,100,000
Liabilities assumed by buyer on sale of transload facilities	2,200,000
Cash consideration received on sale of transload facilities	83,900,000
Gain on sale of transload facilities	5,800,000
Consideration received allocated to asset retirement obligations liabilities of transload facilities	2,100,000
Equipment note assumed the buyer on sale of transload facilities	100,000
Consideration allocated to vendor incentives in sale of transload facilities	60,300,000
Accrued contract termination costs for facilities operated by third parties on sale of transload facilities	7,900,000
Settlement credit for contract termination costs on facilities operated by third parties on sale of transload facilities							$ 2,700,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Permian, Eagle Ford, and Appalachian Basins \| CIG Logistics \| Accounts payables and accrued liabilities
Property, Plant and Equipment
Consideration allocated to vendor incentives in sale of transload facilities		26,600,000	26,600,000	12,500,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Permian, Eagle Ford, and Appalachian Basins \| CIG Logistics \| Other long-term obligations
Property, Plant and Equipment
Consideration allocated to vendor incentives in sale of transload facilities				33,800,000
Machinery and equipment
Property, Plant and Equipment
Aggregated cost of machinery under finance leases		300,000	300,000
Aggregate cost of machinery and equipment under capital lease		1,152,898,000	1,152,898,000	958,357,000
Accumulated amortization of finance lease assets		200,000	200,000
Assets held under capital leases
Property, Plant and Equipment
Aggregate cost of machinery and equipment under capital lease				500,000
Accumulated depreciation of machinery and equipment under capital lease				200,000
Mining property and mine development
Property, Plant and Equipment
Aggregate cost of machinery and equipment under capital lease		$ 794,899,000	794,899,000	995,759,000
Interest cost capitalized in property, plant and mine development			$ 2,000,000.0	$ 6,700,000
Transload facilities \| Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Permian, Eagle Ford, and Appalachian Basins \| CIG Logistics
Property, Plant and Equipment
Consideration received allocated to fair value of transload facilities	25,800,000
Net book value of transload facilities	$ 20,000,000.0

Goodwill and Intangible Assets - Changes in Carrying Amount of Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended	12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Roll Forward]
Beginning balance			$ 261,340	$ 261,340	$ 272,079
Impairments				0	(164,167)
Ending balance	$ 261,340			273,524	261,340
Goodwill	425,507				425,507
Impairment losses	(164,167)				(164,167)
MS Sand
Goodwill [Roll Forward]
Beginning balance	25,322				22,522
Measurement period adjustment		$ 2,800			2,800
Ending balance		$ 25,322
EPMH
Goodwill [Roll Forward]
Beginning balance			150,628	150,628
Measurement period adjustment			12,184	12,184
Acquisition					150,628
Ending balance	150,628		$ 162,812		150,628
Oil & Gas Proppants
Goodwill [Roll Forward]
Beginning balance					247,467
Impairments					(164,167)
Ending balance				86,100
Goodwill	250,267				250,267
Impairment losses	(164,167)				(164,167)
Oil & Gas Proppants \| MS Sand
Goodwill [Roll Forward]
Measurement period adjustment					2,800
Oil & Gas Proppants \| EPMH
Goodwill [Roll Forward]
Measurement period adjustment				0
Acquisition					0
Industrial & Specialty Products
Goodwill [Roll Forward]
Beginning balance					24,612
Impairments					0
Ending balance				187,424
Goodwill	175,240				175,240
Impairment losses	$ 0				0
Industrial & Specialty Products \| MS Sand
Goodwill [Roll Forward]
Measurement period adjustment					0
Industrial & Specialty Products \| EPMH
Goodwill [Roll Forward]
Measurement period adjustment				$ 12,184
Acquisition					$ 150,628

Goodwill and Intangible Assets - Changes in the Carrying Amount of Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets
Gross Carrying Amount	$ 154,782	$ 152,280
Accumulated Amortization	(35,817)	(24,994)
Impairments	(1,240)	0
Net	117,725	127,286
Total Intangible Assets
Gross Carrying Amount	220,872	224,098
Accumulated Amortization	(35,817)	(24,994)
Impairments	(1,240)	(4,478)
Intangible assets, net	183,815	194,626
Trade names
Indefinite-lived Intangible Assets
Gross Carrying Amount	65,390	71,118
Impairments	0	(4,478)
Net	65,390	66,640
Other
Indefinite-lived Intangible Assets
Gross Carrying Amount	700	700
Impairments	0	0
Net	700	700
Technology and intellectual property
Finite-Lived Intangible Assets
Gross Carrying Amount	86,183	83,616
Accumulated Amortization	(17,080)	(11,168)
Impairments	0	0
Net	69,103	72,448
Total Intangible Assets
Accumulated Amortization	(17,080)	(11,168)
Customer relationships
Finite-Lived Intangible Assets
Gross Carrying Amount	68,599	68,664
Accumulated Amortization	(18,737)	(13,826)
Impairments	(1,240)	0
Net	48,622	54,838
Total Intangible Assets
Accumulated Amortization	$ (18,737)	$ (13,826)

Goodwill and Intangible Assets - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill impairment				$ 0	$ 164,167
Amortization expense				$ 10,800	$ 9,700	$ 8,800
Technology and intellectual property
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated useful live of finite-lived intangible assets				15 years
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated useful live of finite-lived intangible assets				20 years
EPMH
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangibles, measurement period adjustment			$ (1,500)
Identifiable intangible assets - indefinite lived			$ (1,250)
EPMH \| Technology and intellectual property
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangibles, measurement period adjustment	$ 1,500
Trade names \| EPMH
Acquired Finite-Lived Intangible Assets [Line Items]
Identifiable intangible assets - indefinite lived	$ 1,300
Oil & Gas Sand \| Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Impairment of finite-lived intangibles				$ 1,200
Oil & Gas Sand \| Trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Impairment of indefinite-lived intangibles		$ 4,500
Oil & Gas Sand
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill impairment		$ 164,200
Maximum \| Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated useful live of finite-lived intangible assets				15 years
Minimum \| Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated useful live of finite-lived intangible assets				13 years

Goodwill and Intangible Assets - Estimated Amortization Expense Related to Definite-Lived Intangible Assets (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2020	$ 10,863
2021	10,861
2022	10,846
2023	10,841
2024	$ 10,843

Accounts Payable and Accrued Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Trade payables	$ 181,029	$ 166,296
Accrued salaries and wages	12,385	12,291
Accrued vacation liability	3,053	3,503
Current portion of liability for pension and post-retirement benefits	2,993	2,708
Accrued healthcare liability	4,078	2,702
Accrued property taxes and sales taxes	4,070	4,490
Vendor incentives	26,617	12,508
Other accrued liabilities	14,012	11,902
Accounts payable and accrued liabilities	248,237	$ 216,400
Decrease to trade payables due to reclassifications	$ 12,500

Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Line of Credit Facility
Less: Unamortized original issue discount	$ (5,412)	$ (6,511)
Less: Unamortized debt issuance cost	(25,390)	(31,310)
Finance leases	70	344
Total debt	1,232,448	1,259,755
Less: current portion	(18,463)	(13,327)
Total long-term portion of debt	1,213,985	1,246,428
Notes Payable \| Insurance financing notes payable
Line of Credit Facility
Short-term debt	5,055	0
Notes Payable \| Note payable secured by royalty interest
Line of Credit Facility
Long-term debt	10,438	26,511
Notes Payable \| Equipment notes payable
Line of Credit Facility
Long-term debt	87	321
Revolving Line-of-Credit \| Revolver
Line of Credit Facility
Long-term debt	$ 0	$ 0
Credit facility, interest rate	7.75%	8.50%
Senior Secured Credit Facility \| Term Loan
Line of Credit Facility
Long-term debt	$ 1,247,600	$ 1,270,400
Credit facility, interest rate	5.81%	6.56%

Debt - Additional Information (Details)		1 Months Ended	3 Months Ended	12 Months Ended
Debt - Additional Information (Details)	May 01, 2018 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Aug. 16, 2016 USD ($)
Debt Instrument [Line Items]
Gain recorded due to changes in fair value of debt				$ 16,854,000	$ 0	$ 0
Insurance financing notes payable \| Notes Payable
Debt Instrument [Line Items]
Debt stated interest rate		4.50%	4.50%
Debt term		10 months
Notes payable balance				5,055,000	$ 0
Senior Secured Credit Facility \| Term Loan
Debt Instrument [Line Items]
Credit facility consolidated total net leverage ratio	3.75
Debt repurchased		$ 10,000,000	$ 10,000,000
Debt redemption price percentage			95.50%
Debt issuance costs			$ 400,000
Gain on extinguishment of debt			$ 100,000
Senior Secured Credit Facility \| Revolver
Debt Instrument [Line Items]
Net leverage ratio, credit facility threshold percentage	30.00%
Revolving Line-of-Credit \| Revolver
Debt Instrument [Line Items]
Available borrowing base				100,000,000.0
Amount drawn under credit facility				0
Amount available under credit facility				93,500,000
Letter of Credit \| Revolver
Debt Instrument [Line Items]
Amount allocated for letters of credit				$ 6,500,000
Current consolidated leverage ratio				4.30
Current borrowing capacity under credit facility without consent of lenders				$ 30,000,000.0
Senior Secured Credit Facility
Debt Instrument [Line Items]
Debt issued	$ 1,380,000,000
Senior Secured Credit Facility \| Term Loan
Debt Instrument [Line Items]
Debt issued	1,280,000,000
Senior Secured Credit Facility \| Revolving Line-of-Credit \| Revolver
Debt Instrument [Line Items]
Available borrowing base	100,000,000
Capitalized debt issuance costs	$ 38,700,000
Notes Payable \| Note payable secured by royalty interest
Debt Instrument [Line Items]
Annual minimum payments				500,000
Debt fair value				10,400,000			$ 22,500,000
Gain recorded due to changes in fair value of debt				$ 16,900,000
Interest rate, effective percentage				14.00%
Notes Payable \| Note payable secured by royalty interest \| Measurement Input, Discount Rate
Debt Instrument [Line Items]
Fair value discount rate							0.14

Debt - Contractual Maturities of Senior Secured Credit Facility (Details) - Senior Secured Credit Facility - Term Loan - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
2020	$ 12,800
2021	12,800
2022	12,800
2023	12,800
2024	12,800
Thereafter	1,183,600
Total	$ 1,247,600	$ 1,270,400

Debt - Contractual Maturities of Note Payable Secured by Royalty Interest (Details) - Notes Payable - Note payable secured by royalty interest $ in Thousands	Dec. 31, 2019 USD ($)
Debt Instrument [Line Items]
2020	$ 454
2021	378
2022	434
2023	499
2024	570
Thereafter	$ 8,103

Deferred Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
Deferred Revenue (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred Revenue Arrangement [Line Items]
Deferred revenue, advances received	$ 12,225	$ 31,625
Deferred revenue	50,634	113,319	$ 118,414
Deferred revenue, current	$ 15,111	$ 31,612
Supply Agreement \| Minimum
Deferred Revenue Arrangement [Line Items]
Deferred revenue, average initial contract term	one
Supply Agreement \| Maximum
Deferred Revenue Arrangement [Line Items]
Deferred revenue, average initial contract term	fifteen

Asset Retirement Obligations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Asset Retirement Obligation Disclosure [Abstract]
Other long-term liabilities related to asset retirement obligation	$ 25,800	$ 18,400
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance	18,413	19,032
Accretion	1,531	1,214
Additions and revisions of prior estimates	5,881	(319)
Addition related to EPMH acquisition	0	2,733
EPMH measurement period adjustment	0	(2,131)
Disposal related to sale of transloads	0	(2,116)
Ending balance	$ 25,825	$ 18,413

Derivative Instruments - Estimated Fair Values of Derivative Instruments (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Interest rate swap agreement $440 million
Derivative Instruments, Gain (Loss)
Contract/Notional Amount	$ 440,000,000	$ 440,000,000
Carrying Amount	(2,768,000)	(1,475,000)
Fair Value	$ (2,768,000)	$ (1,475,000)
Interest rate swap agreement $440 million \| LIBOR
Derivative Instruments, Gain (Loss)
Derivative, basis spread on variable rate (up to)	2.74%	2.74%
Interest rate swap agreement $200 million
Derivative Instruments, Gain (Loss)
Contract/Notional Amount	$ 200,000,000	$ 200,000,000
Carrying Amount	(1,259,000)	(663,000)
Fair Value	$ (1,259,000)	$ (663,000)
Interest rate swap agreement $200 million \| LIBOR
Derivative Instruments, Gain (Loss)
Derivative, basis spread on variable rate (up to)	2.74%	2.74%
Interest rate cap agreement
Derivative Instruments, Gain (Loss)
Contract/Notional Amount	$ 0	$ 249,000,000
Carrying Amount	0	0
Fair Value	$ 0	0
Fair Value, Measurements, Recurring \| Interest rate cap agreement
Derivative Instruments, Gain (Loss)
Fair Value		$ 0

Derivative Instruments - Additional Information (Details)	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($) derivative	Dec. 31, 2017 USD ($)
Derivative [Line Items]
Recognized deferred losses on derivatives in accumulated other comprehensive income into earnings	$ 0	$ 77,000	$ 1,000
Interest rate swap agreement $440 million
Derivative [Line Items]
Fair value of derivatives	2,768,000	1,475,000
Ineffective portion of derivative contracts	0
Interest rate swap agreement $440 million \| Payables and accrued liabilities \| Cash Flow Hedges
Derivative [Line Items]
Fair value of derivatives	2,800,000
Interest rate swap agreement $440 million \| Other long-term obligations \| Cash Flow Hedges
Derivative [Line Items]
Fair value of derivatives		$ 1,500,000
Derivative number of instruments held \| derivative		2
Interest rate swap agreement $200 million
Derivative [Line Items]
Fair value of derivatives	1,259,000	$ 663,000
Interest rate swap agreement $200 million \| Payables and accrued liabilities \| Cash Flow Hedges
Derivative [Line Items]
Fair value of derivatives	1,300,000
Interest rate swap agreement $200 million \| Other long-term obligations \| Cash Flow Hedges
Derivative [Line Items]
Fair value of derivatives		700,000
Interest rate cap agreement
Derivative [Line Items]
Fair value of derivatives	$ 0	0
Recognized deferred losses on derivatives in accumulated other comprehensive income into earnings		$ 76,000

Derivative Instruments - Effect of Derivatives Instruments on Combined Statements of Operations and Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred Losses from Derivatives in OCI [Roll Forward]
Deferred losses from derivatives in OCI, beginning of period	$ (1,621)	$ (76)	$ (32)
(Loss) gain recognized in OCI from derivative instruments	(1,432)	(1,622)	(45)
Loss reclassified from Accumulated OCI	0	77	1
Deferred losses from derivatives in OCI, end of period	$ (3,053)	$ (1,621)	$ (76)

Equity-Based Compensation - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted (in shares)	0	0	0
Stock options exercised (in shares)	10,000	4,167	43,774
Intrinsic value of stock options exercised	$ 12,000	$ 100,000	$ 1,200,000
Proceeds from options exercised	128,000	61,000	798,000
Tax benefit realized for deductions from stock options exercises	3,000	14,000	400,000
Unrecognized compensation expense related to stock options	0
Stock options excluded
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized equity-based compensation		1,400,000	2,500,000
Restricted Stock and Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized equity-based compensation	$ 8,200,000	$ 7,600,000	$ 7,100,000
Awards share units granted (in shares)	814,387	415,110	156,164
Recognized weighted-average period	1 year 9 months 18 days
Unrecognized compensation expense related to awards	$ 10,500,000
Grant date fair value of awards granted (in dollars per share)	$ 13.42
Vesting period for awards of equity instruments	3 years
Performance Share Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized equity-based compensation	$ 7,700,000	$ 13,300,000	$ 15,500,000
Awards share units granted (in shares)	607,130	261,500	90,501
Recognized weighted-average period	1 year 8 months 12 days
Unrecognized compensation expense related to awards	$ 7,400,000
Grant date fair value of awards granted (in dollars per share)	$ 15.58	$ 31.24	$ 67.69
Vesting period for awards of equity instruments	3 years
2011 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock that may be issued (in shares)	1,769,759

Equity-Based Compensation - Stock Options Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Number of Shares
Outstanding at December 31, 2018 (in shares)	901,996
Granted (in shares)	0	0	0
Exercised (in shares)	(10,000)	(4,167)	(43,774)
Forfeited (in shares)	0
Expired (in shares)	(65,338)
Outstanding at December 31, 2019 (in shares)	826,658	901,996
Exercisable at December 31, 2019 (in shares)	826,658
Weighted Average Exercise Price
Outstanding at December 31, 2018, (in dollars per share)	$ 28.52
Granted (in dollars per share)	0
Exercised (in dollars per share)	12.87
Forfeited (in dollars per share)	0
Expired (in dollars per share)	25.16
Outstanding at December 31, 2019, (in dollars per share)	28.97	$ 28.52
Exercisable at December 31, 2019 (in dollars per share)	$ 28.97
Aggregate Intrinsic Value (in thousands)
Outstanding, aggregate intrinsic value	$ 0	$ 18,566
Exercisable, aggregate intrinsic value	$ 11,557
Weighted Average Remaining Contractual Term in Years
Outstanding, weighted average remaining contractual term in years	4 years 1 month 6 days	4 years 9 months 18 days
Exercisable, weighted average remaining contractual term in years	4 years 1 month 6 days

Equity-Based Compensation - Restricted Stock and Restricted Stock Units Activity (Details) - Restricted Stock and Restricted Stock Units - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Number of Shares
Unvested, December 31, 2018 (in shares)	587,577
Granted (in shares)	814,387	415,110	156,164
Vested (in shares)	(306,806)
Forfeited (in shares)	(74,910)
Unvested, December 31, 2019 (in shares)	1,020,248	587,577
Grant Date Weighted Average Fair Value
Unvested, December 31, 2018 (in dollars per share)	$ 25.18
Granted (in dollars per share)	13.42
Vested (in dollars per share)	26.18
Forfeited (in dollars per share)	20.09
Unvested, December 31, 2019 (in dollars per share)	$ 15.86	$ 25.18

Equity-Based Compensation - Performance Share Unit Activity (Details) - Performance Share Units - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Number of Shares
Unvested, December 31, 2018 (in shares)	838,188
Granted (in shares)	607,130	261,500	90,501
Vested (in shares)	(523,368)
Forfeited/Canceled (in shares)	(83,228)
Unvested, December 31, 2019 (in shares)	838,722	838,188
Weighted Average
Unvested, December 31, 2018 (in dollars per share)	$ 39.44
Granted (in dollars per share)	15.58	$ 31.24	$ 67.69
Vested (in dollars per share)	37.83
Forfeited/Canceled (in dollars per share)	25.60
Unvested, December 31, 2019 (in dollars per share)	$ 18.00	$ 39.44

Commitments and Contingencies - Future Minimum Annual Commitments (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Minimum Purchase Commitments
2020	$ 14,512
2021	9,253
2022	6,900
2023	6,900
2024	3,593
Thereafter	2,490
Total future purchase commitments	$ 43,648

Commitments and Contingencies - Additional Information (Details)		12 Months Ended
	May 17, 2017 USD ($)	Dec. 31, 2019 USD ($) claim	Dec. 31, 2018 USD ($) claim	Dec. 31, 2017 claim
Loss Contingencies
Purchased reserves	$ 94,400,000
Surety Bonds
Loss Contingencies
Surety bonds outstanding		$ 42,600,000
Reclamation Bonds
Loss Contingencies
Surety bonds outstanding		30,900,000
Other non-current assets
Loss Contingencies
Third party products claims liability under insurance in other long-term obligations		0	$ 0
Other long-term obligations
Loss Contingencies
Third party products claims liability under insurance in other long-term obligations		$ 900,000	$ 900,000
Pending Litigation
Loss Contingencies
Number of new claims filed \| claim		1	20	0
Number of pending claims \| claim		58

Pension and Post-Retirement Benefits - Net Pension and Post-Retirement Benefit Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits
Pension Plans, Postretirement and Other Employee Benefits
Service cost	$ 1,304	$ 1,307	$ 1,037
Interest cost	5,375	4,632	3,971
Expected return on plan assets	(6,171)	(5,969)	(5,265)
Net amortization and deferral	1,648	2,526	1,773
Net pension benefit or post-retirement costs	2,156	2,496	1,516
Post-retirement Benefits
Pension Plans, Postretirement and Other Employee Benefits
Service cost	88	102	107
Interest cost	789	740	753
Expected return on plan assets	0	0	(1)
Unrecognized net (gain)/loss	(29)	0	0
Net pension benefit or post-retirement costs	$ 848	$ 842	$ 859

Pension and Post-Retirement Benefits - Changes in Benefit Obligations and Plan Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at January 1,	$ 102,396
Fair value of plan assets at December 31,	110,431	$ 102,396
Pension Benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at January 1,	138,900	122,052
Service cost	1,304	1,307	$ 1,037
Interest cost	5,375	4,632	3,971
Actuarial (gain) loss	17,225	(10,263)
Benefits paid	(14,922)	(8,202)
Other	609	29,374
Benefit obligation at December 31,	148,491	138,900	122,052
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at January 1,	102,396	92,067
Actual return on plan assets	17,919	(6,204)
Employer contributions	4,755	3,350
Benefits paid	(14,922)	(8,202)
Other	283	21,385
Fair value of plan assets at December 31,	110,431	102,396	92,067
Plan assets less than benefit obligations at December 31 recognized as liability for pension and other post-retirement benefits	(38,060)	(36,504)
Post-retirement Benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at January 1,	21,570	22,771
Service cost	88	102	107
Interest cost	789	740	753
Actuarial (gain) loss	206	(965)
Benefits paid	(815)	(1,499)
Other	216	421
Benefit obligation at December 31,	22,054	21,570	22,771
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at January 1,	0	0
Actual return on plan assets	0	0
Employer contributions	599	1,078
Benefits paid	(815)	(1,499)
Other	216	421
Fair value of plan assets at December 31,	0	0	$ 0
Plan assets less than benefit obligations at December 31 recognized as liability for pension and other post-retirement benefits	$ (22,054)	$ (21,570)

Pension and Post-Retirement Benefits - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) plan	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Pension Plans, Postretirement and Other Employee Benefits
Projected benefit obligation, nonqualified pension plan	$ 1.6	$ 1.5
Defined benefit plan, pension plans with accumulated benefit obligations in excess of plan assets, aggregate accumulated benefit obligation	1.6	1.5
Fair value of plan assets, nonqualified pension plan	0.0	0.0
Defined benefit plan, accumulated other comprehensive income net gains (losses), after tax	22.1	17.6
Defined benefit plan, accumulated other comprehensive income net prior service cost (credit), after tax	$ 2.2	$ 2.8
Number of multiemployer defined benefit plans \| plan	3
Percentage of contributions to individual multiemployer pension funds	5.00%	5.00%	5.00%
Company contributing percentage on defined benefit plan (up to)	50.00%
Employee contribution over defined benefit plan	4.00%
Company contributions to defined contribution plan	$ 6.1	$ 2.6	$ 3.0
Certain Employees
Pension Plans, Postretirement and Other Employee Benefits
Company contribution over defined benefit plan	4.00%
Some Employees
Pension Plans, Postretirement and Other Employee Benefits
Employee contribution over defined benefit plan	6.00%
Company contribution on profit sharing match	100.00%
Pension Benefits
Pension Plans, Postretirement and Other Employee Benefits
Accumulated benefit obligation	$ 148.5	$ 138.9
Expected contributions to the plans for next fiscal year	$ 5.1
Weighted average discount rate used to determine projected pension and post-retirement obligations	3.20%	4.40%
Post-retirement Benefits
Pension Plans, Postretirement and Other Employee Benefits
Expected contributions to the plans for next fiscal year	$ 1.4
Weighted average discount rate used to determine projected pension and post-retirement obligations	3.20%	4.30%

Pension and Post-Retirement Benefits - Estimated Future Pension and Post-Retirement Benefit Payments (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Pension Benefits
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2020	$ 10,025
2021	9,221
2022	9,195
2023	9,208
2024	9,551
2025-2029	45,386
Post-retirement Benefits \| Before Medicare Subsidy
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2020	1,601
2021	1,669
2022	1,686
2023	1,659
2024	1,677
2025-2029	7,526
Post-retirement Benefits \| After Medicare Subsidy
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2020	1,431
2021	1,502
2022	1,520
2023	1,492
2024	1,513
2025-2029	$ 6,677

Pension and Post-Retirement Benefits - Amounts in Accumulated Other Comprehensive Income Expected to be Recognized as Components of Net Periodic Benefit Cost (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Pension Plans, Postretirement and Other Employee Benefits
Net actuarial loss	$ 2,532
Prior service cost	534
Total	3,066
Pension Benefits
Pension Plans, Postretirement and Other Employee Benefits
Net actuarial loss	2,532
Prior service cost	534
Total	3,066
Post-retirement Benefits
Pension Plans, Postretirement and Other Employee Benefits
Net actuarial loss	0
Prior service cost	0
Total	$ 0

Pension and Post-Retirement Benefits - Weighted-Average Assumptions Used (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits
Pension Plans, Postretirement and Other Employee Benefits
Discount rate	3.20%	4.40%
Long-term rate of return on plan assets	6.30%
Pension Benefits \| Minimum
Pension Plans, Postretirement and Other Employee Benefits
Long-term rate of compensation increase	3.00%	3.00%
Long-term rate of return on plan assets		6.25%
Pension Benefits \| Maximum
Pension Plans, Postretirement and Other Employee Benefits
Long-term rate of compensation increase	3.50%	3.50%
Long-term rate of return on plan assets		7.15%
Post-retirement Health Care
Pension Plans, Postretirement and Other Employee Benefits
Discount rate	3.20%	4.30%
Post-retirement Health Care \| Pre-65 \| Minimum
Pension Plans, Postretirement and Other Employee Benefits
Initial rate	7.00%	7.30%
Post-retirement Health Care \| Pre-65 \| Maximum
Pension Plans, Postretirement and Other Employee Benefits
Ultimate rate	4.50%	4.50%
Post-retirement Health Care \| Post-65 \| Minimum
Pension Plans, Postretirement and Other Employee Benefits
Initial rate	7.50%	8.00%
Post-retirement Health Care \| Post-65 \| Maximum
Pension Plans, Postretirement and Other Employee Benefits
Ultimate rate	4.50%	4.50%

Pension and Post-Retirement Benefits - Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates (Details) - Post-retirement Benefits $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Effect on total of service and interest cost, increase	$ 100
Effect on post-retirement benefit obligation, increase	2,341
Effect on total of service and interest cost, decrease	(85)
Effect on post-retirement benefit obligation, decrease	$ (2,010)

Pension and Post-Retirement Benefits - Investment Categories and Their Relative Percentage of Fair Value to Total Plan Assets (Details)	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits \| Equity securities
Pension Plans, Postretirement and Other Employee Benefits
Percentage of the fair value of the total plan assets	52.10%	42.10%
Pension Benefits \| Debt securities
Pension Plans, Postretirement and Other Employee Benefits
Percentage of the fair value of the total plan assets	46.60%	55.50%
Pension Benefits \| Cash
Pension Plans, Postretirement and Other Employee Benefits
Percentage of the fair value of the total plan assets	1.30%	2.40%
Post-retirement Benefits \| Equity securities
Pension Plans, Postretirement and Other Employee Benefits
Percentage of the fair value of the total plan assets	0.00%	0.00%
Post-retirement Benefits \| Debt securities
Pension Plans, Postretirement and Other Employee Benefits
Percentage of the fair value of the total plan assets	0.00%	0.00%
Post-retirement Benefits \| Cash
Pension Plans, Postretirement and Other Employee Benefits
Percentage of the fair value of the total plan assets	0.00%	0.00%

Pension and Post-Retirement Benefits - Summary of Multiemployer Pension Plan (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
LIUNA
Pension Plans, Postretirement and Other Employee Benefits
EIN/ Pension Plan No.	52-6074345/001
Pension Protection Act Zone Status	Red
Company Contributions (in thousands)	$ 385,000	$ 573,000	$ 223,000
Surcharge Imposed	Yes
Expiration Date of CBA	May 31, 2020
IUOE
Pension Plans, Postretirement and Other Employee Benefits
EIN/ Pension Plan No.	36-6052390/001
Pension Protection Act Zone Status	Green
Company Contributions (in thousands)	$ 310,000	1,385,000	40,000
Surcharge Imposed	No
Expiration Date of CBA	Jul. 31, 2022
CSSS
Pension Plans, Postretirement and Other Employee Benefits
EIN/ Pension Plan No.	36-6044243/001
Pension Protection Act Zone Status	Red
Company Contributions (in thousands)	$ 51,000	$ 51,000	$ 51,000
Central States, Southeast and Southwest Areas Pension Plan
Pension Plans, Postretirement and Other Employee Benefits
Withdrawal liability from pension plan	1,000,000.0
Withdrawal liability paid on monthly installments	$ 4,000

Leases - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Lessee, Lease, Description [Line Items]
Impairment recognized on operating lease right-of-use assets	$ 115,400	$ 115,443	$ 0
Minimum
Lessee, Lease, Description [Line Items]
Remaining term of lease contracts		1 year
Maximum
Lessee, Lease, Description [Line Items]
Remaining term of lease contracts		20 years

Leases - Supplemental Balance Sheet Information (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Leases [Abstract]
Operating lease right-of-use assets	$ 53,098
Current portion of operating lease liabilities	53,587
Operating lease liabilities	117,964
Total lease liabilities	$ 171,551
Operating leases, weighted average remaining lease term (years)	4 years 6 months
Operating leases, weighted average discount rate	5.70%

Leases - Components of Lease Expense (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Cost of Sales
Lessee, Lease, Description [Line Items]
Operating lease costs	$ 88,966
Short-term operating lease costs	18,200
Selling, general, and administrative
Lessee, Lease, Description [Line Items]
Operating lease costs	3,993
Total lease costs	208,402
Short-term operating lease costs	700
Goodwill and other asset impairments
Lessee, Lease, Description [Line Items]
Operating lease costs	$ 115,443

Leases - Supplemental Cash Flow Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Leases [Abstract]
Cash paid for amounts included in the measurement of lease liabilities, operating leases	$ 74,740
Right-of-use assets obtained in exchange for new lease liabilities, operating leases	$ 232,123

Leases - Maturities of Lease Liabilities (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Leases [Abstract]
2020	$ 63,337
2021	44,276
2022	33,526
2023	22,380
2024	16,236
Thereafter	22,284
Total lease payments	202,039
Less: Interest	30,488
Total	$ 171,551

Income Taxes - Income Tax Benefit (Expense) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current:
Federal									$ 0	$ 1,076	$ (10,754)
State									(1,188)	(2,496)	(1,167)
Foreign									(1,343)	(518)	0
Current income tax (expense) benefit									(2,531)	(1,938)	(11,921)
Deferred:
Federal									90,457	25,578	22,641
State									11,225	5,492	(2,040)
Foreign									0	0	0
Deferred income tax (expense) benefit									101,682	31,070	20,601
Income tax benefit	$ 91,892	$ 7,671	$ (2,384)	$ 1,972	$ 37,938	$ 1,547	$ (2,832)	$ (7,521)	$ 99,151	$ 29,132	$ 8,680

Income Taxes - Effective Income Tax Rate on Pretax Earnings (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income tax benefit (expense) computed at U.S. federal statutory rate									$ 90,070	$ 48,290	$ (47,784)
Decrease (increase) resulting from:
Statutory depletion									4,679	12,090	20,259
Goodwill impairment									0	(29,157)	0
Prior year tax return reconciliation									3,121	530	219
State income taxes, net of federal benefit									9,486	2,592	(2,267)
Adjustment to deferred taxes from the Tax Act rate reduction									0	0	35,772
Equity compensation									(6,440)	(653)	2,602
Other, net									(1,765)	(4,560)	(121)
Income tax benefit	$ 91,892	$ 7,671	$ (2,384)	$ 1,972	$ 37,938	$ 1,547	$ (2,832)	$ (7,521)	$ 99,151	$ 29,132	$ 8,680

Income Taxes - Tax Effects on Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Gross deferred tax assets:
Net operating loss carry forward and state tax credits	$ 32,173	$ 11,089
Pension and post-retirement benefit costs	13,976	13,303
Alternative minimum tax credit carry forward	7,895	15,971
Property, plant and equipment	7,179	5,474
Accrued expenses	15,336	27,025
Inventories	6,507	774
Third-party products liability	236	231
Stock-based compensation expense	2,390	8,199
Note payable	109	3,724
Interest expense limitation	22,324	0
Lease obligation liability	29,604	0
Other	5,191	8,116
Total deferred tax assets	142,920	93,906
Gross deferred tax liabilities:
Land and mineral property basis difference	(124,182)	(165,002)
Fixed assets and depreciation	(44,314)	(55,596)
Intangibles	(12,541)	(10,346)
Other	(468)	(201)
Total deferred tax liabilities	(181,505)	(231,145)
Net deferred tax liabilities	$ (38,585)	$ (137,239)

Income Taxes - Additional Information (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
Alternative minimum tax credit carry forward	$ 16.2	$ 16.0
Alternative minimum tax reclassified from deferred tax assets to other receivables	8.1	$ 16.0
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 122.3

Revenue - Sales by Major Source (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Total Sales									$ 1,474,477	$ 1,577,298	$ 1,240,851
Oil & Gas Proppants
Disaggregation of Revenue [Line Items]
Total Sales									1,010,521	1,182,991
Industrial & Specialty Products
Disaggregation of Revenue [Line Items]
Total Sales									463,956	394,307
Product
Disaggregation of Revenue [Line Items]
Total Sales	$ 280,594	$ 287,977	$ 303,041	$ 296,860	$ 293,419	$ 348,635	$ 345,957	$ 294,788	1,168,472	1,282,799	1,010,394
Product \| Oil & Gas Proppants
Disaggregation of Revenue [Line Items]
Total Sales									704,516	888,509
Product \| Industrial & Specialty Products
Disaggregation of Revenue [Line Items]
Total Sales									463,956	394,290
Service
Disaggregation of Revenue [Line Items]
Total Sales	$ 58,465	$ 73,837	$ 91,813	$ 81,890	$ 63,961	$ 74,537	$ 81,476	$ 74,525	306,005	294,499	$ 230,457
Service \| Oil & Gas Proppants
Disaggregation of Revenue [Line Items]
Total Sales									306,005	294,482
Service \| Industrial & Specialty Products
Disaggregation of Revenue [Line Items]
Total Sales									$ 0	$ 17

Revenue - Changes in Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Unbilled Receivables
Beginning Balance	$ 90	$ 5,245
Reclassifications to billed receivables	(3,983)	(11,157)
Revenues recognized in excess of period billings	4,037	6,002
Ending Balance	144	90
Deferred Revenue
Beginning Balance	113,319	118,414
Revenues recognized from balances held at the beginning of the period	(65,225)	(33,381)
Revenues deferred from period collections on unfulfilled performance obligations	12,225	31,625
Revenues recognized from period collections	(9,685)	(3,339)
Ending Balance	$ 50,634	$ 113,319

Revenue - Remaining Performance Obligations (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Revenue from Contract with Customer [Abstract]
Recognized revenue as variable consideration from shortfall penalties according to contract terms From Shortfall Penalties	$ 70.6
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining duration period of expected satisfaction of performance obligations	1 year

Revenue - Foreign Operations (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Consolidated sales									$ 1,474,477	$ 1,577,298	$ 1,240,851
Consolidated assets	$ 2,553,234				$ 2,900,840				2,553,234	2,900,840
Pre-tax income	(385,317)	$ (30,736)	$ 8,445	$ (21,300)	(294,013)	$ 4,769	$ 20,476	$ 38,815	(428,908)	(229,953)	136,526
Net income	(292,871)	$ (23,037)	$ 6,150	$ (19,324)	(256,062)	$ 6,316	$ 17,644	$ 31,294	(329,082)	(200,808)	$ 145,206
Foreign Operations
Disaggregation of Revenue [Line Items]
Consolidated sales									92,800	66,900
Consolidated assets	$ 27,700				$ 7,300				27,700	7,300
Pre-tax income									7,000	5,900
Net income									$ 5,500	$ 4,700

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Related Party Transactions (Details) - USD ($)	12 Months Ended
Related Party Transactions (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Related party purchases	$ 0	$ 2,958,000	$ 4,942,000
Officer \| Transportation Brokerage and Logistics Services Vendor
Related Party Transaction [Line Items]
Related party purchases	$ 0	$ 2,900,000	$ 4,700,000

Segment Reporting - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) Segment Product	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Segment Reporting Information
Number of reportable segments \| Segment	2
Number of product types \| Product	400
Goodwill	$ 273,524	$ 261,340	$ 272,079
Oil & Gas Proppants
Segment Reporting Information
Goodwill	86,100		247,467
Industrial & Specialty Products
Segment Reporting Information
Goodwill	187,424		$ 24,612
Operating Segments \| Oil & Gas Proppants
Segment Reporting Information
Goodwill	86,100	86,100
Operating Segments \| Industrial & Specialty Products
Segment Reporting Information
Goodwill	$ 187,400	$ 175,240

Segment Reporting - Sales and Segment Contribution Margin for Reporting Segments and Other Operating Results (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information
Total sales									$ 1,474,477	$ 1,577,298	$ 1,240,851
Selling, general and administrative	$ (37,325)	$ (40,208)	$ (38,659)	$ (34,656)	$ (32,168)	$ (37,980)	$ (42,232)	$ (34,591)	(150,848)	(146,971)	(107,056)
Depreciation, depletion and amortization	(42,819)	(47,126)	(44,899)	(44,600)	(46,527)	(37,150)	(36,563)	(28,592)	(179,444)	(148,832)	(97,233)
Goodwill and other asset impairments	(363,717)	(130)	0	0	(265,715)	0	(16,184)	0	(363,847)	(281,899)	0
Interest expense	(22,996)	(24,733)	(23,765)	(23,978)	(21,281)	(21,999)	(20,214)	(7,070)	(95,472)	(70,564)	(31,342)
Other income (expense), net, including interest income	443	3,280	15,074	722	1,336	1,062	1,081	665	19,519	4,144	(1,874)
Income tax benefit	91,892	7,671	(2,384)	1,972	37,938	1,547	(2,832)	(7,521)	99,151	29,132	8,680
Net (loss) income	(293,425)	(23,065)	6,061	(19,328)	(256,075)	6,316	17,644	31,294	(329,757)	(200,821)	145,206
Less: Net loss attributable to non-controlling interest	(554)	(28)	(89)	(4)	(13)	0	0	0	(675)	(13)	0
Net (loss) income attributable to U.S. Silica Holdings, Inc.	$ (292,871)	$ (23,037)	$ 6,150	$ (19,324)	$ (256,062)	$ 6,316	$ 17,644	$ 31,294	(329,082)	(200,808)	145,206
Operating Segments
Segment Reporting Information
Total sales									1,474,477	1,577,298	1,240,851
Total segment contribution margin									426,809	512,930	390,753
Segment Reconciling Items
Segment Reporting Information
Operating activities excluded from segment cost of sales(1)									(85,625)	(98,761)	(16,722)
Selling, general and administrative									(150,848)	(146,971)	(107,056)
Depreciation, depletion and amortization									(179,444)	(148,832)	(97,233)
Goodwill and other asset impairments									(363,847)	(281,899)	0
Interest expense									(95,472)	(70,564)	(31,342)
Other income (expense), net, including interest income									19,519	4,144	(1,874)
Oil & Gas Proppants
Segment Reporting Information
Total sales									1,010,521	1,182,991
Oil & Gas Proppants \| Operating Segments
Segment Reporting Information
Total sales									1,010,521	1,182,991	1,020,365
Total segment contribution margin									248,594	357,846	301,972
Industrial & Specialty Products
Segment Reporting Information
Total sales									463,956	394,307
Industrial & Specialty Products \| Operating Segments
Segment Reporting Information
Total sales									463,956	394,307	220,486
Total segment contribution margin									$ 178,215	$ 155,084	$ 88,781

Unaudited Supplementary Data (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Sales:
Total sales									$ 1,474,477	$ 1,577,298	$ 1,240,851
Cost of sales (excluding depreciation, depletion and amortization):
Total cost of sales (excluding depreciation, depletion and amortization)									1,133,293	1,163,129	866,820
Operating expenses:
Selling, general and administrative	$ 37,325	$ 40,208	$ 38,659	$ 34,656	$ 32,168	$ 37,980	$ 42,232	$ 34,591	150,848	146,971	107,056
Depreciation, depletion and amortization	42,819	47,126	44,899	44,600	46,527	37,150	36,563	28,592	179,444	148,832	97,233
Goodwill and other asset impairments	363,717	130	0	0	265,715	0	16,184	0	363,847	281,899	0
Total operating expenses	443,861	87,464	83,558	79,256	344,410	75,130	94,979	63,183	694,139	577,702	204,289
Operating (loss) income	(362,764)	(9,283)	17,136	1,956	(274,068)	25,706	39,609	45,220	(352,955)	(163,533)	169,742
Other (expense) income:
Interest expense	(22,996)	(24,733)	(23,765)	(23,978)	(21,281)	(21,999)	(20,214)	(7,070)	(95,472)	(70,564)	(31,342)
Other income (expense), net, including interest income	443	3,280	15,074	722	1,336	1,062	1,081	665	19,519	4,144	(1,874)
Total other expense	(22,553)	(21,453)	(8,691)	(23,256)	(19,945)	(20,937)	(19,133)	(6,405)	(75,953)	(66,420)	(33,216)
(Loss) income before income taxes	(385,317)	(30,736)	8,445	(21,300)	(294,013)	4,769	20,476	38,815	(428,908)	(229,953)	136,526
Income tax benefit	91,892	7,671	(2,384)	1,972	37,938	1,547	(2,832)	(7,521)	99,151	29,132	8,680
Net (loss) income	(293,425)	(23,065)	6,061	(19,328)	(256,075)	6,316	17,644	31,294	(329,757)	(200,821)	145,206
Less: Net loss attributable to non-controlling interest	(554)	(28)	(89)	(4)	(13)	0	0	0	(675)	(13)	0
Net (loss) income attributable to U.S. Silica Holdings, Inc.	$ (292,871)	$ (23,037)	$ 6,150	$ (19,324)	$ (256,062)	$ 6,316	$ 17,644	$ 31,294	$ (329,082)	$ (200,808)	$ 145,206
Basic (loss) earnings per share (in dollars per share)	$ (4.00)	$ (0.31)	$ 0.08	$ (0.26)	$ (3.44)	$ 0.08	$ 0.23	$ 0.39	$ (4.49)	$ (2.63)	$ 1.79
Diluted (loss) earnings per share (in dollars per share)	$ (4.00)	$ (0.31)	$ 0.08	$ (0.26)	$ (3.44)	$ 0.08	$ 0.22	$ 0.39	$ (4.49)	$ (2.63)	$ 1.77
Weighted average shares outstanding, basic (in shares)	73,343	73,328	73,301	73,040	74,485	77,365	77,784	79,496	73,253	76,453	81,051
Weighted average common shares outstanding, diluted (in shares)	73,343	73,328	73,505	73,040	74,485	77,859	78,480	80,309
Dividends declared per share (in dollars per share)	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.25	$ 0.25	$ 0.25
Product
Sales:
Total sales	$ 280,594	$ 287,977	$ 303,041	$ 296,860	$ 293,419	$ 348,635	$ 345,957	$ 294,788	$ 1,168,472	$ 1,282,799	$ 1,010,394
Cost of sales (excluding depreciation, depletion and amortization):
Total cost of sales (excluding depreciation, depletion and amortization)	212,905	226,797	225,473	234,916	241,624	270,370	236,236	207,239	900,091	955,469	714,521
Service
Sales:
Total sales	58,465	73,837	91,813	81,890	63,961	74,537	81,476	74,525	306,005	294,499	230,457
Cost of sales (excluding depreciation, depletion and amortization):
Total cost of sales (excluding depreciation, depletion and amortization)	$ 45,057	$ 56,836	$ 68,687	$ 62,622	$ 45,414	$ 51,966	$ 56,609	$ 53,671	$ 233,202	$ 207,660	$ 152,299

Parent Company Financials - Condensed Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current Assets:
Cash and cash equivalents	$ 185,740	$ 202,498
Total current assets	509,040	600,237
Total assets	2,553,234	2,900,840
Current Liabilities:
Accounts payable and accrued expenses	248,237	216,400
Total current liabilities	335,398	261,339
Total liabilities	1,836,654	1,848,536
Stockholders’ Equity:
Common stock	823	818
Additional paid-in capital	1,185,116	1,169,383
Retained (deficit) earnings	(279,956)	67,854
Treasury stock, at cost	(180,912)	(178,215)
Accumulated other comprehensive loss	(19,854)	(15,020)
Total U.S. Silica Holdings, Inc. stockholders’ equity	705,217	1,044,820
Non-controlling interest	11,363	7,484
Total stockholders' equity	716,580	1,052,304	$ 1,396,506	$ 1,273,290
Total liabilities and stockholders’ equity	2,553,234	2,900,840
Parent Company
Current Assets:
Cash and cash equivalents	51,849	107,151
Due from affiliates	138,988	100,094
Total current assets	190,837	207,245
Investment in subsidiaries	530,830	850,099
Total assets	721,667	1,057,344
Current Liabilities:
Accounts payable and accrued expenses	129	217
Dividends payable	4,958	4,823
Total current liabilities	5,087	5,040
Total liabilities	5,087	5,040
Stockholders’ Equity:
Preferred stock	0	0
Common stock	823	818
Additional paid-in capital	1,185,116	1,169,383
Retained (deficit) earnings	(279,956)	67,854
Treasury stock, at cost	(180,912)	(178,215)
Accumulated other comprehensive loss	(19,854)	(15,020)
Total U.S. Silica Holdings, Inc. stockholders’ equity	705,217	1,044,820
Non-controlling interest	11,363	7,484
Total stockholders' equity	716,580	1,052,304	$ 1,396,506	$ 1,273,290
Total liabilities and stockholders’ equity	$ 721,667	$ 1,057,344

Parent Company Financials - Condensed Statements of Operations and Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Income Statements, Captions [Line Items]
Total sales									$ 1,474,477	$ 1,577,298	$ 1,240,851
Operating expenses:
Selling, general and administrative	$ 37,325	$ 40,208	$ 38,659	$ 34,656	$ 32,168	$ 37,980	$ 42,232	$ 34,591	150,848	146,971	107,056
Total operating expenses	443,861	87,464	83,558	79,256	344,410	75,130	94,979	63,183	694,139	577,702	204,289
Operating (loss) income	(362,764)	(9,283)	17,136	1,956	(274,068)	25,706	39,609	45,220	(352,955)	(163,533)	169,742
Other income (expense)
Total other expense	(22,553)	(21,453)	(8,691)	(23,256)	(19,945)	(20,937)	(19,133)	(6,405)	(75,953)	(66,420)	(33,216)
Income tax benefit	91,892	7,671	(2,384)	1,972	37,938	1,547	(2,832)	(7,521)	99,151	29,132	8,680
Net (loss) income	(293,425)	(23,065)	6,061	(19,328)	(256,075)	6,316	17,644	31,294	(329,757)	(200,821)	145,206
Less: Net loss attributable to non-controlling interest	(554)	(28)	(89)	(4)	(13)	0	0	0	(675)	(13)	0
Net (loss) income attributable to U.S. Silica Holdings, Inc.	$ (292,871)	$ (23,037)	$ 6,150	$ (19,324)	$ (256,062)	$ 6,316	$ 17,644	$ 31,294	(329,082)	(200,808)	145,206
Other comprehensive (loss) income
Unrealized loss on derivatives									(1,432)	(1,545)	(44)
Foreign currency translation adjustment (net of tax of $(60), $(196), and $2 for 2019, 2018 and 2017, respectively)									(188)	(614)	(6)
Pension and other post-retirement benefits liability adjustment (net of tax of $(1,024), $339, and $1,205 for 2019, 2018 and 2017, respectively)									(3,214)	1,065	2,000
Comprehensive (loss) income									(334,591)	(201,915)	147,156
Less: Comprehensive loss attributable to non-controlling interest									(675)	(13)	0
Comprehensive (loss) income attributable to U.S. Silica Holdings, Inc.									(333,916)	(201,902)	147,156
Tax expense (benefit) on unrealized gain (loss) on derivatives									(456)	(470)	(27)
Tax expense (benefit) on foreign currency translation adjustment									(60)	(196)	2
Tax (expense) benefit on pension and other post-retirement benefits liability adjustment									(1,024)	339	1,205
Parent Company
Condensed Income Statements, Captions [Line Items]
Total sales									0	0	0
Cost of sales									0	0	0
Operating expenses:
Selling, general and administrative									253	254	252
Total operating expenses									253	254	252
Operating (loss) income									(253)	(254)	(252)
Other income (expense)
Interest income									1,440	2,784	3,854
Total other expense									1,440	2,784	3,854
Income before income taxes and equity in net earnings of subsidiaries									1,187	2,530	3,602
Income tax benefit									(327)	(696)	(1,453)
Income before equity in net earnings of subsidiaries									860	1,834	2,149
Equity in earnings of subsidiaries, net of tax									(330,617)	(202,655)	143,057
Net (loss) income									(329,757)	(200,821)	145,206
Less: Net loss attributable to non-controlling interest									(675)	(13)	0
Net (loss) income attributable to U.S. Silica Holdings, Inc.									(329,082)	(200,808)	145,206
Other comprehensive (loss) income
Unrealized loss on derivatives									(1,432)	(1,545)	(44)
Foreign currency translation adjustment (net of tax of $(60), $(196), and $2 for 2019, 2018 and 2017, respectively)									(188)	(614)	(6)
Pension and other post-retirement benefits liability adjustment (net of tax of $(1,024), $339, and $1,205 for 2019, 2018 and 2017, respectively)									(3,214)	1,065	2,000
Comprehensive (loss) income									(334,591)	(201,915)	147,156
Less: Comprehensive loss attributable to non-controlling interest									(675)	(13)	0
Comprehensive (loss) income attributable to U.S. Silica Holdings, Inc.									(333,916)	(201,902)	147,156
Tax expense (benefit) on unrealized gain (loss) on derivatives									(456)	(470)	(27)
Tax expense (benefit) on foreign currency translation adjustment									(60)	(196)	2
Tax (expense) benefit on pension and other post-retirement benefits liability adjustment									$ (1,024)	$ 339	$ 1,205

Parent Company Financials - Condensed Statements of Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance				$ 1,052,304				$ 1,396,506	$ 1,052,304	$ 1,396,506	$ 1,273,290
Net (loss) income	$ (293,425)	$ (23,065)	$ 6,061	$ (19,328)	$ (256,075)	$ 6,316	$ 17,644	$ 31,294	(329,757)	(200,821)	145,206
Unrealized loss on derivatives									(1,432)	(1,545)	(44)
Foreign currency translation adjustment									(188)	(614)	(6)
Pension and post-retirement liability									(3,214)	1,065	2,000
Cash dividend declared ($0.25 per share for 2019, 2018 and 2017, respectively)									(18,728)	(19,330)	(20,387)
Contributions from non-controlling interest									4,554	7,497
Equity-based compensation									15,906	22,337	25,050
Proceeds from options exercised									128	61	798
Issuance of restricted stock											0
Shares withheld for tax payments related to vested restricted stock and stock units									(2,993)	(4,383)	(4,379)
Repurchase of common stock										(148,469)	(25,022)
Ending Balance	705,217				1,044,820				705,217	1,044,820
Ending Balance	$ 716,580				$ 1,052,304				$ 716,580	$ 1,052,304	$ 1,396,506
Dividends declared per share (in dollars per share)	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.25	$ 0.25	$ 0.25
Total U.S. Silica Holdings Inc., Stockholders’ Equity
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance				$ 1,044,820				$ 1,396,506	$ 1,044,820	$ 1,396,506	$ 1,273,290
Net (loss) income									(329,082)	(200,808)	145,206
Unrealized loss on derivatives									(1,432)	(1,545)	(44)
Foreign currency translation adjustment									(188)	(614)	(6)
Pension and post-retirement liability									(3,214)	1,065	2,000
Cash dividend declared ($0.25 per share for 2019, 2018 and 2017, respectively)									(18,728)	(19,330)	(20,387)
Equity-based compensation									15,906	22,337	25,050
Proceeds from options exercised									128	61	798
Shares withheld for tax payments related to vested restricted stock and stock units									(2,993)	(4,383)	(4,379)
Repurchase of common stock										(148,469)	(25,022)
Ending Balance	$ 705,217				$ 1,044,820				705,217	1,044,820	1,396,506
Common Stock
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance				818				812	818	812	811
Shares withheld for tax payments related to vested restricted stock and stock units									5	6	1
Ending Balance	823				818				823	818	812
Treasury Stock
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance				(178,215)				(25,456)	(178,215)	(25,456)	(3,869)
Proceeds from options exercised									296	93	1,190
Issuance of restricted stock											1,859
Shares withheld for tax payments related to vested restricted stock and stock units									(2,993)	(4,383)	386
Repurchase of common stock										(148,469)	(25,022)
Ending Balance	(180,912)				(178,215)				(180,912)	(178,215)	(25,456)
Additional Paid-In Capital
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance				1,169,383				1,147,084	1,169,383	1,147,084	1,129,051
Equity-based compensation									15,906	22,337	25,050
Proceeds from options exercised									(168)	(32)	(392)
Issuance of restricted stock											(1,859)
Shares withheld for tax payments related to vested restricted stock and stock units									(5)	(6)	(4,766)
Ending Balance	1,185,116				1,169,383				1,185,116	1,169,383	1,147,084
Retained Earnings
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance				67,854				287,992	67,854	287,992	163,173
Net (loss) income									(329,082)	(200,808)	145,206
Cash dividend declared ($0.25 per share for 2019, 2018 and 2017, respectively)									(18,728)	(19,330)	(20,387)
Ending Balance	(279,956)				67,854				(279,956)	67,854	287,992
Accumulated Other Comprehensive Loss
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance				(15,020)				(13,926)	(15,020)	(13,926)	(15,876)
Unrealized loss on derivatives									(1,432)	(1,545)	(44)
Foreign currency translation adjustment									(188)	(614)	(6)
Pension and post-retirement liability									(3,214)	1,065	2,000
Ending Balance	(19,854)				(15,020)				(19,854)	(15,020)
Ending Balance	(19,854)				(15,020)				(19,854)	(15,020)	(13,926)
Non-controlling Interest
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance				7,484				0	7,484	0	0
Net (loss) income									(675)	(13)
Contributions from non-controlling interest									4,554	7,497
Ending Balance	11,363				7,484				11,363	7,484	0
Parent Company
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance				1,052,304				1,396,506	1,052,304	1,396,506	1,273,290
Net (loss) income									(329,757)	(200,821)	145,206
Unrealized loss on derivatives									(1,432)	(1,545)	(44)
Foreign currency translation adjustment									(188)	(614)	(6)
Pension and post-retirement liability									(3,214)	1,065	2,000
Cash dividend declared ($0.25 per share for 2019, 2018 and 2017, respectively)									(18,728)	(19,330)	(20,387)
Contributions from non-controlling interest									4,554	7,497
Equity-based compensation									15,906	22,337	25,050
Proceeds from options exercised									128	61	798
Shares withheld for tax payments related to vested restricted stock and stock units									(2,993)	(4,383)	(4,379)
Repurchase of common stock										(148,469)	(25,022)
Ending Balance	705,217				1,044,820				705,217	1,044,820
Ending Balance	716,580				1,052,304				$ 716,580	$ 1,052,304	$ 1,396,506
Dividends declared per share (in dollars per share)									$ 0.25	$ 0.25	$ 0.25
Parent Company \| Total U.S. Silica Holdings Inc., Stockholders’ Equity
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance				1,044,820				1,396,506	$ 1,044,820	$ 1,396,506	$ 1,273,290
Net (loss) income									(329,082)	(200,808)	145,206
Unrealized loss on derivatives									(1,432)	(1,545)	(44)
Foreign currency translation adjustment									(188)	(614)	(6)
Pension and post-retirement liability									(3,214)	1,065	2,000
Cash dividend declared ($0.25 per share for 2019, 2018 and 2017, respectively)									(18,728)	(19,330)	(20,387)
Equity-based compensation									15,906	22,337	25,050
Proceeds from options exercised									128	61	798
Shares withheld for tax payments related to vested restricted stock and stock units									(2,993)	(4,383)	(4,379)
Repurchase of common stock										(148,469)	(25,022)
Ending Balance	705,217				1,044,820				705,217	1,044,820	1,396,506
Parent Company \| Common Stock
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance				818				812	818	812	811
Shares withheld for tax payments related to vested restricted stock and stock units									5	6	1
Ending Balance	823				818				823	818	812
Parent Company \| Treasury Stock
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance				(178,215)				(25,456)	(178,215)	(25,456)	(3,869)
Proceeds from options exercised									296	93	1,190
Issuance of restricted stock											1,859
Shares withheld for tax payments related to vested restricted stock and stock units									(2,993)	(4,383)	386
Repurchase of common stock										(148,469)	(25,022)
Ending Balance	(180,912)				(178,215)				(180,912)	(178,215)	(25,456)
Parent Company \| Additional Paid-In Capital
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance				1,169,383				1,147,084	1,169,383	1,147,084	1,129,051
Equity-based compensation									15,906	22,337	25,050
Proceeds from options exercised									(168)	(32)	(392)
Issuance of restricted stock											(1,859)
Shares withheld for tax payments related to vested restricted stock and stock units									(5)	(6)	(4,766)
Ending Balance	1,185,116				1,169,383				1,185,116	1,169,383	1,147,084
Parent Company \| Retained Earnings
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance				67,854				287,992	67,854	287,992	163,173
Net (loss) income									(329,082)	(200,808)	145,206
Cash dividend declared ($0.25 per share for 2019, 2018 and 2017, respectively)									(18,728)	(19,330)	(20,387)
Ending Balance	(279,956)				67,854				(279,956)	67,854	287,992
Parent Company \| Accumulated Other Comprehensive Loss
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance				(15,020)				(13,926)	(15,020)	(13,926)	(15,876)
Unrealized loss on derivatives									(1,432)	(1,545)	(44)
Foreign currency translation adjustment									(188)	(614)	(6)
Pension and post-retirement liability									(3,214)	1,065	2,000
Ending Balance	(19,854)				(15,020)				(19,854)	(15,020)	(13,926)
Parent Company \| Non-controlling Interest
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance				$ 7,484				$ 0	7,484	0	0
Net (loss) income									(675)	(13)	0
Contributions from non-controlling interest									4,554	7,497
Ending Balance	$ 11,363				$ 7,484				$ 11,363	$ 7,484	$ 0

Parent Company Financials - Condensed Statements of Cash Flows (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Cash Flow Statements, Captions [Line Items]
Net (loss) income	$ (293,425,000)	$ (23,065,000)	$ 6,061,000	$ (19,328,000)	$ (256,075,000)	$ 6,316,000	$ 17,644,000	$ 31,294,000	$ (329,757,000)	$ (200,821,000)	$ 145,206,000
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Accounts payable and accrued expenses									21,024,000	26,907,000	43,654,000
Net cash provided by operating activities									144,046,000	310,706,000	222,013,000
Investing activities:
Net cash used in investing activities									(120,393,000)	(1,066,879,000)	(491,529,000)
Financing activities:
Repurchase of common stock									0	(148,469,000)	(25,022,000)
Proceeds from options exercised									128,000	61,000	798,000
Tax payments related to shares withheld for vested restricted stock and stock units									(2,993,000)	(4,383,000)	(4,379,000)
Contributions from non-controlling interest									4,554,000	7,497,000	0
Net cash (used in) provided by financing activities									(40,411,000)	574,104,000	(57,142,000)
Net decrease in cash and cash equivalents									(16,758,000)	(182,069,000)	(326,658,000)
Cash and cash equivalents, beginning of period				202,498,000				384,567,000	202,498,000	384,567,000	711,225,000
Cash and cash equivalents, end of period	185,740,000				202,498,000				185,740,000	202,498,000	384,567,000
Cash (received) paid during the period for:
Interest									(87,286,000)	(66,769,000)	(24,490,000)
Cash dividends paid to the parent by its consolidated entities									0	0	0
Parent Company
Condensed Cash Flow Statements, Captions [Line Items]
Net (loss) income									(329,757,000)	(200,821,000)	145,206,000
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Undistributed loss (income) from equity method investment, net									330,617,000	202,655,000	(143,057,000)
Accounts payable and accrued expenses									(88,000)	(295,000)	48,000
Net cash provided by operating activities									772,000	1,539,000	2,197,000
Investing activities:
Investment in subsidiary									0	0	(143,654,000)
Net cash used in investing activities									0	0	(143,654,000)
Financing activities:
Dividends paid									(18,592,000)	(19,912,000)	(20,377,000)
Repurchase of common stock									0	(148,469,000)	(25,022,000)
Proceeds from options exercised									128,000	61,000	798,000
Tax payments related to shares withheld for vested restricted stock and stock units									(2,993,000)	(4,383,000)	(4,379,000)
Contributions from non-controlling interest									4,554,000	7,497,000	0
Net financing activities with subsidiaries									(39,171,000)	40,171,000	(113,294,000)
Net cash (used in) provided by financing activities									(56,074,000)	(125,035,000)	(162,274,000)
Net decrease in cash and cash equivalents									(55,302,000)	(123,496,000)	(303,731,000)
Cash and cash equivalents, beginning of period				$ 107,151,000				$ 230,647,000	107,151,000	230,647,000	534,378,000
Cash and cash equivalents, end of period	$ 51,849,000				$ 107,151,000				51,849,000	107,151,000	230,647,000
Cash (received) paid during the period for:
Interest									$ (1,440,000)	$ (2,784,000)	$ (3,853,000)

Impairments (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
Impairments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure Text Block Supplement [Abstract]
Inventories, net									$ 4,100	$ 3,316
Property, plant and mine development, net									243,064	109,938
Operating lease right-of-use assets	$ 115,400								115,443	0
Goodwill									0	164,167
Intangible assets, net									1,240	4,478
Total	$ 363,717	$ 130	$ 0	$ 0	$ 265,715	$ 0	$ 16,184	$ 0	$ 363,847	$ 281,899	$ 0

Impairments - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of property, plant and equipment			$ 243,064	$ 109,938
Impairment recognized on operating lease right-of-use assets	$ 115,400		115,443	0
Goodwill impairment			0	$ 164,167
Oil & Gas Sand
Impaired Long-Lived Assets Held and Used [Line Items]
Goodwill impairment		$ 164,200
Oil & Gas Sand \| Customer relationships
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of finite-lived intangibles			$ 1,200
Oil & Gas Sand \| Trade names
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of indefinite-lived intangibles		$ 4,500

Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended								12 Months Ended
	Feb. 10, 2020	Jan. 03, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Subsequent Event
Cash dividend paid											$ 18,728	$ 19,330	$ 20,387
Cash dividend declared (in dollars per share)			$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.25	$ 0.25	$ 0.25
Subsequent Event
Subsequent Event
Cash dividend paid		$ 4,600
Cash dividend paid (in dollars per share)		$ 0.0625
Cash dividend declared (in dollars per share)	$ 0.02

Pension and Post-Retirement Benefits - Fair Value of Pension Plan Assets, by Asset Category (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	$ 110,431	$ 102,396
Cash and cash equivalents
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	1,385	2,449
Diversified emerging markets
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	4,942	6,638
Foreign large blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	19,183	11,689
Large-cap blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	20,738	14,226
Mid-cap blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	8,416	6,819
Small-cap blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets		522
Real estate
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	4,309	3,192
Corporate notes and bonds
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	37,664	43,745
U.S. Treasuries
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	10,894	8,486
Mortgage-backed securities
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	2,496	3,578
Asset-backed securities
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	404	1,052
Level 1
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	106,146	95,317
Level 1 \| Cash and cash equivalents
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 1 \| Diversified emerging markets
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	4,942	6,638
Level 1 \| Foreign large blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	19,183	11,689
Level 1 \| Large-cap blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	20,738	14,226
Level 1 \| Mid-cap blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	8,416	6,819
Level 1 \| Small-cap blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets		522
Level 1 \| Real estate
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	4,309	3,192
Level 1 \| Corporate notes and bonds
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	37,664	43,745
Level 1 \| U.S. Treasuries
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	10,894	8,486
Level 1 \| Mortgage-backed securities
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 1 \| Asset-backed securities
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 2
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	4,285	7,079
Level 2 \| Cash and cash equivalents
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	1,385	2,449
Level 2 \| Diversified emerging markets
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 2 \| Foreign large blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 2 \| Large-cap blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 2 \| Mid-cap blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 2 \| Small-cap blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets		0
Level 2 \| Real estate
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 2 \| Corporate notes and bonds
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 2 \| U.S. Treasuries
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 2 \| Mortgage-backed securities
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	2,496	3,578
Level 2 \| Asset-backed securities
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	404	1,052
Level 3
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 3 \| Cash and cash equivalents
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 3 \| Diversified emerging markets
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 3 \| Foreign large blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 3 \| Large-cap blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 3 \| Mid-cap blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 3 \| Small-cap blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets		0
Level 3 \| Real estate
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 3 \| Corporate notes and bonds
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 3 \| U.S. Treasuries
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 3 \| Mortgage-backed securities
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 3 \| Asset-backed securities
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	$ 0	$ 0