Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2016	Feb. 21, 2017	Jun. 30, 2016
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2016
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	FY
Entity Registrant Name	U.S. Silica Holdings, Inc.
Entity Central Index Key	0001524741
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		81,061,840
Entity Public Float			$ 1,562,047,655

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current Assets:
Cash and cash equivalents	$ 711,225	$ 277,077
Short-term investments	0	21,849
Accounts receivable, net	89,006	58,706
Inventories, net	78,709	65,004
Prepaid expenses and other current assets	12,323	9,921
Income tax deposits	1,682	6,583
Total current assets	892,945	439,140
Property, plant and mine development, net	783,313	561,196
Goodwill	240,975	68,647
Trade names	32,318	14,474
Intellectual property	57,270	0
Customer relationships, net	50,890	6,453
Other assets	15,509	18,709
Total assets	2,073,220	1,108,619
Current Liabilities:
Accounts payable	70,778	49,631
Dividends payable	5,221	3,453
Accrued liabilities	13,034	11,708
Accrued interest	169	58
Current portion of long-term debt	4,821	3,330
Current portion of capital leases	2,237	0
Current portion of deferred revenue	13,700	15,738
Total current liabilities	109,960	83,918
Long-term debt	508,417	488,375
Liability for pension and other post-retirement benefits	56,746	55,893
Deferred revenue	58,090	59,676
Deferred income taxes, net	50,075	19,513
Obligations under capital lease	717	0
Other long-term obligations	15,925	17,077
Total liabilities	799,930	724,452
Stockholders’ Equity:
Preferred stock	0	0
Common stock	811	539
Additional paid-in capital	1,129,051	194,670
Retained earnings	163,173	220,974
Treasury stock, at cost	(3,869)	(15,845)
Accumulated other comprehensive loss	(15,876)	(16,171)
Total stockholders’ equity	1,273,290	384,167
Total liabilities and stockholders’ equity	$ 2,073,220	$ 1,108,619

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
Sales	$ 559,625	$ 642,989	$ 876,741
Cost of goods sold (excluding depreciation, depletion and amortization)	477,295	495,066	566,584
Operating expenses
Selling, general and administrative	67,727	62,777	88,971
Depreciation, depletion and amortization	68,134	58,474	45,019
Total operating expenses	135,861	121,251	133,990
Operating income (loss)	(53,531)	26,672	176,167
Other income (expense)
Interest expense	(27,972)	(27,283)	(18,202)
Other income, net, including interest income	3,758	728	758
Total other (expenses) income	(24,214)	(26,555)	(17,444)
Income (loss) before income taxes	(77,745)	117	158,723
Income tax benefit (expense)	36,689	11,751	(37,183)
Net income (loss)	$ (41,056)	$ 11,868	$ 121,540
Earnings (loss) per share:
Basic (in usd per share)	$ (0.63)	$ 0.22	$ 2.26
Diluted (in usd per share)	$ (0.63)	$ 0.22	$ 2.24
Weighted average shares outstanding:
Weighted Average Number of Shares Outstanding, Basic (in shares)	65,037	53,344	53,719
Weighted Average Number of Shares Outstanding, Diluted (in shares)	65,037	53,601	54,296
Dividend declared per share (in usd per share)	$ 0.25	$ 0.438	$ 0.50

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ (6,942)	$ (11,339)	$ (11,772)	$ (11,003)	$ (15,320)	$ 2,412	$ 9,953	$ 14,823	$ (41,056)	$ 11,868	$ 121,540
Other comprehensive income:
Unrealized gain (loss) on derivatives (net of tax of $29, $34 and ($32) for 2016, 2015, and 2014, respectively)									49	53	(55)
Unrealized gain (loss) on investments (net of tax of ($4), $29 and ($8) for 2016, 2015, and 2014, respectively)									(6)	47	(14)
Pension and other post-retirement benefits liability adjustment (net of tax of $152, $2,469 and ($9,678) for 2016, 2015, and 2014, respectively)									252	3,547	(15,732)
Comprehensive income									$ (40,761)	$ 15,515	$ 105,739

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Tax expense (benefit) on unrealized gain (loss) on derivatives	$ 29	$ 34	$ (32)
Tax expense (benefit) on unrealized gain (loss) on investments	(4)	29	(8)
Tax expense (benefit) on pension and other post-retirement benefits liability adjustment	$ 152	$ 2,469	$ (9,678)

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total stockholders’ equity	$ 309,294	$ 534	$ 0	$ 174,799	$ 137,978	$ (4,017)
Beginning balance at Dec. 31, 2013	309,294	534	0	174,799	137,978	(4,017)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	121,540				121,540
Unrealized gain (loss) on derivatives	(55)					(55)
Unrealized gain (loss) on short-term investments	(14)					(14)
Pension and post-retirement liability	(15,732)					(15,732)
Cash dividends declared ($0.25, $0.438 and $0.50 per share of common stock for 2016, 2015 and 2014 respectively))	(26,967)				(26,967)
Equity-based compensation	7,487			7,487
Excess tax benefit from equity-based compensation	3,813			3,813
Proceeds from options exercised	5,563	4	572	4,987
Shares withheld for employee taxes related to vested restricted stock and stock units	(614)	1	(615)	0
Repurchase of common stock	(499)		(499)
Total stockholders’ equity	309,294	534	0	174,799	137,978	(4,017)
Total stockholders’ equity	403,816	539	(542)	191,086	232,551	(19,818)
Beginning balance at Dec. 31, 2014	403,816	539	(542)	191,086	232,551	(19,818)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	11,868				11,868
Unrealized gain (loss) on derivatives	53					53
Unrealized gain (loss) on short-term investments	47					47
Pension and post-retirement liability	3,547					3,547
Cash dividends declared ($0.25, $0.438 and $0.50 per share of common stock for 2016, 2015 and 2014 respectively))	(23,445)				(23,445)
Equity-based compensation	3,857			3,857
Proceeds from options exercised	473		744	(271)
Shares withheld for employee taxes related to vested restricted stock and stock units	(794)		(792)	(2)
Repurchase of common stock	(15,255)		(15,255)
Total stockholders’ equity	403,816	539	(542)	191,086	232,551	(19,818)
Total stockholders’ equity	384,167	539	(15,845)	194,670	220,974	(16,171)
Beginning balance at Dec. 31, 2015	384,167	539	(15,845)	194,670	220,974	(16,171)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(41,056)				(41,056)
Issuance of common stock (stock offerings net of issuance costs of $25,732)	931,288	272		931,016
Unrealized gain (loss) on derivatives	49					49
Unrealized gain (loss) on short-term investments	(6)					(6)
Pension and post-retirement liability	252					252
Cash dividends declared ($0.25, $0.438 and $0.50 per share of common stock for 2016, 2015 and 2014 respectively))	(16,893)				(16,893)
Equity-based compensation	12,107			12,107
Excess tax benefit from equity-based compensation	148				148
Proceeds from options exercised	4,825		8,465	(3,640)
Issuance of restricted stock	0		1,437	(1,437)
Shares withheld for employee taxes related to vested restricted stock and stock units	(1,591)		2,074	(3,665)
Total stockholders’ equity	384,167	539	(15,845)	194,670	220,974	(16,171)
Total stockholders’ equity	$ 1,273,290	$ 811	$ (3,869)	$ 1,129,051	$ 163,173	$ (15,876)

Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($)					3 Months Ended								12 Months Ended
	Nov. 03, 2016	Jul. 21, 2016	May 05, 2016	Feb. 22, 2016	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Stockholders' Equity [Abstract]
Dividend declared per share (in usd per share)	$ 0.0625	$ 0.0625	$ 0.0625	$ 0.0625	$ 0.0625	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.125	$ 0.125	$ 0.125	$ 0.25	$ 0.438	$ 0.50
Common stock issuance costs													$ 25,732

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities:
Net income	$ (41,056)	$ 11,868	$ 121,540
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization	68,134	58,474	45,019
Debt issuance amortization	1,392	1,401	912
Original issue discount amortization	378	382	272
Deferred income taxes	(36,903)	(10,473)	(2,442)
Loss on disposal of property, plant and equipment	563	383	222
Deferred revenue	(9,026)	(16,079)	(8,508)
Equity-based compensation	12,107	3,857	7,487
Excess tax benefit from equity-based compensation	0	0	(3,813)
Bad debt provision	(1,232)	(290)	10,200
Other	3,643	(5,257)	367
Changes in assets and liabilities, net of effects of acquisitions:
Accounts receivable	(12,996)	62,465	(48,976)
Inventories	(10,211)	1,708	34
Prepaid expenses and other current assets	(509)	(708)	(2,158)
Income taxes	11,558	(5,837)	2,063
Accounts payable and accrued liabilities	13,121	(42,353)	51,357
Accrued interest	111	(2)	15
Liability for pension and other post-retirement benefits	1,307	1,953	(2,180)
Net cash provided by (used in) operating activities	381	61,492	171,411
Investing activities:
Capital expenditures	(46,450)	(53,646)	(92,609)
Capitalized intellectual property costs	(959)	0	0
Proceeds from sales and maturities of short-term investments	21,872	53,568	0
Acquisition of business, net of cash acquired	(176,617)	0	(98,317)
Proceeds from sale of property, plant and equipment	497	127	20
Net cash provided by (used in) investing activities	(201,657)	49	(190,906)
Financing activities:
Issuance of common stock	678,791	0
Common stock issuance costs	(25,732)	0
Dividends paid	(15,125)	(26,797)	(26,871)
Repurchase of common stock	0	(15,255)	(499)
Proceeds from options exercised	4,825	473	5,563
Excess tax benefit from equity-based compensation	0	0	3,813
Tax payments related to shares withheld for vested restricted stock and stock units	(1,591)	(794)	(614)
Advances from customers	0	0	100,000
Issuance of long-term debt	0	0	134,325
Repayment of long-term debt	(5,202)	(5,093)	(3,750)
Principal payments on capital lease obligations	(542)	0	(132)
Financing fees	0	(64)	(2,871)
Net cash provided by (used in) financing activities	635,424	(47,530)	208,964
Net increase in cash and cash equivalents	434,148	14,011	189,469
Cash and cash equivalents, beginning of period	277,077	263,066	73,597
Cash and cash equivalents, end of period	711,225	277,077	263,066
Cash paid (received) during the period for:
Interest	21,994	21,729	15,920
Taxes	(11,322)	4,568	37,637
Non-cash items:
Common stock issued in connection with acquisitions	278,229	0	0
Capital lease obligations incurred to acquire assets	$ 165	$ 0	$ 0

Organization	12 Months Ended
Organization	Dec. 31, 2016
Accounting Policies [Abstract]
Organization	NOTE A—ORGANIZATION U.S. Silica Holdings, Inc. (“Holdings,” and together with its subsidiaries “we,” “us” or the “Company”) is a domestic producer of commercial silica, a specialized mineral that is a critical input into a variety of end markets. During our 116 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 these markets. We manufacture frac sand used to stimulate and maintain the flow of hydrocarbons in oil and natural gas wells. Our silica is also used as a raw material in a wide range of industrial applications, including glassmaking and chemical manufacturing. We operate in two business segments: (1) Oil & Gas Proppants and (2) Industrial & Specialty Products (see Note S - Segment Reporting for additional details). On August 16, 2016, we completed the acquisition of New Birmingham, Inc. (“NBI”), the ultimate parent company of NBR Sand, LLC (“NBR”), a regional sand producer located near Tyler, Texas. On August 22, 2016, we completed the purchase of all of the outstanding units of membership interest of Sandbox Enterprises, LLC (“Sandbox”), a “last mile” transportation service provider in the oil and gas industry. See Note D - Business Combinations for more details for these two acquisitions.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2016

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 (the “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 Financial Statements have been included. Such adjustments are of a normal, recurring nature. We have reclassified certain immaterial amounts in the prior years’ operating activities section section of the consolidated statement of cash flows to conform to the current year presentation.

In order to make this report easier to read, we refer throughout 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 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”). For the periods presented herein, we have identified no entities over which we maintain any level of control that would qualify for consolidation under ASC guidance.

Use of Estimates and Assumptions

The preparation of the 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 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 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 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; 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.

Revenue Recognition

We derive most of our sales by mining and processing minerals that our customers purchase for various uses. Our sales are primarily a function of the price per ton and the number of tons sold. The amount invoiced reflects product, transportation and additional services as applicable, such as storage, transloading the product from railcars to trucks and last mile logistics to the customer site.

Revenue is recognized from a sale when persuasive evidence of an arrangement exists, the price is fixed and determinable, the product has been delivered, legal title has been transferred to the customer or services are completed and collection of the sale is reasonably assured. Amounts received from customers in advance of revenue recognition are deferred as liabilities.

We primarily sell our products under short-term price agreements or at prevailing market rates. For a limited number of customers, we sell under long-term, competitively-bid take-or-pay supply agreements. As of December 31, 2016, we had seven take-or-pay supply agreements in the Oil & Gas Proppants segment with initial terms expiring between 2017 and 2019. 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 that our customers will pay for each product. Prices under these agreements are generally fixed and subject to upward adjustment in response to certain cost increases. Some of these existing agreements are under active 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 take-or-pay supply agreements.

We invoice the majority of our clients on a per shipment basis, although for some larger customers, we consolidate invoices weekly or monthly. Standard terms are net 30 days, although extended terms are offered in competitive situations. Sales and other transaction taxes imposed by government entities are reported on a net basis.

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 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.

Checks we issued but have not cleared our bank accounts frequently result in book overdraft balances. In 2015, we changed the presentation of book overdraft from being classified as a liability to a reduction to our cash and cash equivalents. As a result of this change, the amount of cash and cash equivalents was reduced by the book overdraft amounts as of December 31, 2016, 2015 and 2014 was $3.2 million, $6.7 million and $4.2 million, respectively.

Accounts Receivable

The majority of our accounts receivable are due from companies in the oil and natural gas drilling, glass, building products, filler and extenders, foundries and other major industries. Our ten largest customers accounted for approximately 52%, 56%, and 57% of sales in the years ended December 31, 2016, 2015 and 2014, respectively. Sales to our largest customer, Halliburton Company, which is an Oil & Gas Proppants customer, accounted for 13% of our total revenues during the year ended December 31, 2016. No other customer accounted for 10% or more of our total revenues. 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 include raw stockpiles and silica and other industrial sand available for shipment, as well as spare parts and supplies for routine facility maintenance. We value inventory at the lower of cost or net realizable value. Cost is determined using the first-in, first-out and average cost methods. Costs of our raw stockpiles and silica and other industrial sand inventories include production costs and transportation and additional service costs as applicable.

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 life 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 has 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.

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 reclamation obligations.

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.

In connection with our annual review of our reclamation obligations, we have determined that some of our estimates required revision due primarily to the additions of new plant and transload facilities and other changes in cost estimates and settlement dates at various sites. These additions and changes in estimates resulted in an additional $(2.1) million and $0.2 million of asset retirement obligations in 2016 and 2015, respectively.

Our asset retirement obligations are reported in other long-term obligations. The changes in these obligations (in thousands) during the year ending December 31, 2016 and 2015 are as follows:



	2016			2015
Beginning balance	$	12,254		$	11,283
Accretion	979			812
Additions and revisions of prior estimates	(2,074		)	159
Ending balance	$	11,159		$	12,254

Impairment or Disposal of Property, Plant and Mine Development

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.

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.

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 was acquired in connection with our Sandbox acquisition and mainly consists of patents and technology. It is amortized on a straight-line basis over an average useful life of 15 years. As of December 31, 2016, the gross carrying amount of the intellectual property intangible asset was $58.7 million with accumulated amortization of $1.4 million. During the year ended December 31, 2016, we capitalized $0.9 million in legal costs and patent filing costs. As of December 31, 2016, the remaining useful life was 14.6 years. The estimated annual amortization in each of the next five years is $3.8 million. Amortization expense for intellectual property was $1.4 million for the year ended December 31, 2016.

Customer relationships are amortized on a straight-line basis over their useful life of 20, 15 or 13 years. We acquired additional customer relationships in connection with our NBI and Sandbox acquisitions during the year ended December 31, 2016. As of December 31, 2016, the gross carrying amount of the customer relationships intangible asset was $55.7 million with accumulated amortization of $4.8 million. As of December 31, 2016, the weighted average remaining useful life of our customer relationships was 13.0 years. The estimated annual amortization in each of the next five years is $4.0 million. Amortization expense was $1.8 million, $0.5 million and $0.4 million for the years ended December 31, 2016, 2015 and 2014, respectively.

Goodwill represents the excess of purchase price over the fair value of net assets from business acquisitions. Goodwill and trade names are reviewed for impairment annually as of October 31 or more frequently whenever events or circumstances change that would more likely than not reduce the fair value of those assets. 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 comparison of the fair value with the carrying amount, including goodwill. If this comparison reflects impairment, then the loss would be measured as the excess of recorded goodwill, or other intangible assets with indefinite lives, over its implied fair value. Implied fair value is the excess of our fair value over the fair value of all recognized and unrecognized assets and liabilities. As of December 31, 2016, our qualitative assessment did not indicate that it was more likely than not that an impairment had occurred.

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 (the “Term Loan”) and the straight-line method for our revolving line-of-credit (the "Revolver"). Debt issuance costs related to long-term debt are reflected as direct deduction from the carrying amount of the debt. Amortization included in interest expense was $1.4 million, $1.4 million and $0.9 million for the years ended December 31, 2016, 2015 and 2014, respectively.

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. 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. For December 31, 2016 and 2015, our self-insurance reserves totaled $5.3 million and $5.7 million, respectively, and $1.3 million and $1.8 million was classified as current, respectively.

Equity-based Compensation

We recognize the cost of employee services rendered in exchange for awards of equity instruments, including stock options, restricted stock, restricted stock units and performance share units.

Vesting of restricted stock and restricted stock units is based on the individual continuing to render service over a three year vesting schedule. 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.

During the year ended December 31, 2016, we granted 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 the three year period from January 1, 2016 through December 31, 2018. 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.

The 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 options granted, we estimate the fair value of each grant using the Black-Scholes option-pricing model. The weighted-average fair value per share of options granted during the years ended December 31, 2015 and 2014 was $13.11 and $19.37, respectively. The fair value of stock options granted have been calculated based on the exercise price of the option and the following assumptions, which are evaluated and revised, as necessary, to reflect market conditions and experience. There were no options granted during the year ended December 31, 2016.



	Weighted-average
	Year ended December 31,
		2015		2014
Risk-free interest rate		1.68	%	1.81	%
Expected volatility		48	%	45	%
Expected term		6.25 years		6.25 years
Expected dividend yield		1	%	1	%
Expected forfeiture rate		0	%	0	%

Our expected forfeiture rate is the estimated percentage of options granted that are expected to be forfeited or canceled on an annual basis before becoming fully vested. 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

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.

Earnings per Share

Basic and diluted earnings per share is presented for net income (loss). 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. In accordance with the applicable accounting guidance for calculating earnings per share, we did not include in our calculation of diluted earnings per share for the applicable periods stock options where the exercise prices were greater than the average market prices. The weighted-average stock options (in thousands) that are antidilutive and are therefore excluded from the calculation of diluted earnings per common share are:



	For the Year Ended December 31,
	2016	2015	2014
Weighted-average outstanding stock options excluded	573	528	33
Weighted-average outstanding restricted stock awards excluded	166	66	20

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, unrealized gain or loss on our short term investments and the effective portion of changes in fair value of derivative instruments that qualify as cash flow hedges.

Short-term Investments

Our short-term investments consist of fixed income securities that have been classified and accounted for as available-for-sale. We determine the appropriate classification of our investments at the time of purchase and reevaluate the designations at each balance sheet date. We classify these securities as either short-term or long-term based on each instrument’s underlying contractual maturity date. Fixed income securities with maturities of 12 months or less are classified as short-term and fixed income securities with maturities greater than 12 months are classified as long-term. These investments are carried at fair value, with the unrealized gains and losses, net of taxes, reported as a separate component of accumulated other comprehensive income. The cost of securities sold is based upon the specific identification method.

We typically invest in highly-rated securities, and our investment policy generally limits the amount of credit exposure to any one issuer. The policy requires investments generally to be investment grade, with the primary objective of minimizing the potential risk of principal loss. Fair values were determined for each individual security in the investment portfolio. When evaluating an investment for other-than-temporary impairment, we review factors such as the length of time and extent to which fair value has been below its cost basis, the financial condition of the issuer and any changes thereto, changes in market interest rates, and our intent to sell, or whether it is more likely than not we will be required to sell, the investment before recovery of the investment’s cost basis. As of December 31, 2015, we considered any losses in our short-term investment portfolio to be temporary in nature and did not consider any of our investments other-than-temporarily impaired. All short-term investments have matured as of December 31, 2016.

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 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. Additional disclosures for derivative instruments are presented in Note M to these financial statements.

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.

Recently Adopted Accounting Pronouncements

In April 2015, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2015-03, Interest-Imputation of Interest, which simplifies presentation of debt issuance costs. The new standard requires that debt issuance costs be presented in the balance sheet as a direct deduction from the carrying amount of debt liability, consistent with debt discounts or premiums. The new standard was effective for financial statements issued for fiscal years beginning after December 15, 2015, and interim periods within fiscal years beginning after December 15, 2016. Early adoption of the amendments in this Update is permitted for financial statements that have not been previously issued. We have elected to adopt the standard early and have presented debt issuance costs as a direct deduction from the carrying amount of debt on our Balance Sheets as of December 31, 2016 and December 31, 2015.

In November 2015, the FASB issued ASU 2015-17, Income Taxes - Balance Sheet Classification of Deferred Taxes, which will require the presentation of deferred tax liabilities and assets be classified as non-current on balance sheets. The amendments in this update are effective for financial statements issued for annual periods beginning after December 15, 2016, and interim periods within those annual periods. Early application is permitted for all entities as of the beginning of an interim or annual reporting period. We have elected to early adopt this guidance prospectively as of December 31, 2015. The adoption only impacted deferred tax presentation on our Balance Sheets and related disclosure. No prior periods were retrospectively adjusted.

In July 2015, the FASB issued ASU 2015-11, Simplifying the Measurement of Inventory. The new standard requires an entity to measure most inventory at the lower of cost and net realizable value, thereby simplifying the current guidance under which an entity must measure inventory at the lower of cost or market. The new standard will not apply to inventories that are measured using either the last-in, first-out (LIFO) method or the retail inventory method. This Update is effective for public entities for financial statements issued for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years; early application is permitted. We elected to prospectively early adopt the standard effective January 1, 2016 and have measured our inventory at the lower of cost and net realizable value on our Balance Sheet. The impacts of the early adoption of this Update on our Financial Statements are not significant.

In March 2016, the FASB issued ASU 2016-09, "Compensation-Stock Compensation." The update requires that excess tax benefits and deficiencies be recorded in the income statement when the awards vest or are settled. It also eliminates the requirement that excess tax benefits be realized (reduce cash taxes payable) before being recognized. Previously, an entity could not recognize excess tax benefits if the tax deduction increased a net operating loss ("NOL") or tax credit carryforward. The updated standard no longer requires cash flows related to excess tax benefits to be presented as a financing activity separate from other income tax cash flows. The update also allows the employer to repurchase more of an employee's shares for tax withholding purposes without triggering liability accounting, clarifies that all cash payments to taxing authorities made on an employee's behalf for withheld shares should be presented as a financing activity on the statement of cash flows, and provides for an accounting policy election to account for forfeitures as they occur. The update is effective for annual periods beginning after December 15, 2016 and interim periods within those annual periods and permits early adoption.

We elected to early adopt this update during the three months ended September 30, 2016, which requires any adjustments to be reflected as of January 1, 2016. This resulted in the recognition of excess tax benefits on our Balance Sheet that were previously not recognized, as the benefits would have increased our NOL or tax credit carryforwards. The recognition decreased net deferred tax liability by $0.1 million and $2.2 million as of January 1, 2016 and December 31, 2016, respectively. Retained earnings on January 1, 2016 was increased accordingly by $0.1 million. In addition, we will recognize excess tax benefits or deficiencies in the provision for income taxes rather than paid-in capital for 2016 and future periods. Adoption of the update resulted in the reduction in the provision for income taxes of $2.2 million for the year ended December 31, 2016.

The effect of the adoption of this update on our previously reported income tax provision on our Income Statement was a decrease in tax benefit of $0.3 million for the three months ended March 31, 2016 and an increase in tax benefit of $0.2 million for the three months ended June 30, 2016, respectively.

We elected to include excess tax benefits as operating activities in the Cash Flow on a prospective basis. Prior periods are not adjusted. We also made the accounting policy election to account for forfeitures as they occur.

Recently Issued Accounting Pronouncements

In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers, which supersedes previous revenue recognition guidance. The new guidance introduces a new principles-based framework for revenue recognition and disclosure. Since its issuance, the FASB has issued an additional six ASUs, including ASU 2016-20 in December 2016, amending the guidance and the effective dates of amendments, and the SEC has rescinded certain related SEC guidance; the most recent of which was issued in May 2016. The pronouncements are effective for annual reporting periods beginning after December 15, 2017, including interim reporting periods within that reporting period. Earlier application is permitted only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period. We have not yet completed our final review of the impact of this guidance, although we currently do not anticipate a material impact on our revenue recognition practices. We continue to review our existing contracts with our customers, any variable consideration, potential disclosures, and our method of adoption to complete our evaluation of the impact on our consolidated financial statements. In addition, we continue to monitor additional changes, modifications, clarifications or interpretations being undertaken by the FASB, which may impact our current conclusions.

In February 2016, the FASB issued ASU 2016-02, Leases, which supersedes the existing lease guidance and requires all leases with a term greater than 12 months to be recognized on the balance sheet as assets and obligations. This Update is effective for public entities for financial statements issued for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years; early application is permitted. This standard mandates a modified retrospective transition method. We have not yet determined the impact from adoption of this new accounting pronouncement on our financial statements.

In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments. The Update provides amendments that clarify guidance or correct references in the Accounting Standards Codification that addresses current diversity in practice and could potentially result in changes in current practice because of either misapplication or misunderstanding of current guidance. Early adoption is permitted for the amendments that require transition guidance. We are currently evaluating the effect that the transition guidance will have on our financial statements and related disclosures.

In December 2016, the FASB issued ASU 2016-19, Technical Corrections and Improvements. Most of the amendments are effective upon issuance. Six amendments clarify guidance or correct references in the Accounting Standards Codification that could potentially result in changes in current practice because of either misapplication or misunderstanding of current guidance. The transition guidance effective dates for these six amendments varies depending upon the amendment, relevant Subtopic and applicability to other ASUs. Early adoption is permitted for the amendments that require transition guidance. We are currently evaluating the effect that the transition guidance will have on our financial statements and related disclosures.

Capital Structure and Accumulated Comprehensive Income

12 Months Ended

Dec. 31, 2016

Equity [Abstract]

Capital Structure and Accumulated Comprehensive Income

NOTE C—CAPITAL STRUCTURE AND ACCUMULATED COMPREHENSIVE INCOME

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.

In March 2016, we completed a public offering of 10,000,000 shares of our common stock for total cash proceeds of approximately $186.2 million net of underwriting discounts and offering costs. In August 2016, we issued an additional 6,825,693 shares of our common stock to complete two acquisitions discussed in Note D - Business Combinations. In November 2016, we executed another offering of 10,350,000 shares of common stock raising net cash proceeds of $467.0 million. There were 81,028,898 shares of common stock issued and outstanding at December 31, 2016. As of December 31, 2015, there were 53,390,136 shares issued and outstanding.

In 2016, our Board of Directors declared quarterly cash dividends as follows:



Dividends per Common Share		Declaration Date	Record Date	Payable Date
$	0.0625	February 22, 2016	March 15, 2016	April 5, 2016
$	0.0625	May 5, 2016	June 15, 2016	July 6, 2016
$	0.0625	July 21, 2016	September 15, 2016	October 4, 2016
$	0.0625	November 3, 2016	December 15, 2016	January 5, 2017

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 conditions, our 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 and to fix the preferences, powers and relative, participating, optional or other special rights and 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 are no shares of preferred stock issued or outstanding at December 31, 2016 and 2015. 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 on the open market or in privately negotiated transactions. As of December 31, 2016, we are authorized to repurchase up to $50 million of our common stock through December 11, 2017. Stock repurchases 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. Under our share repurchase program, as of December 31, 2016, we have repurchased 706,093 shares of our common stock at an average price of $23.83 and are authorized to repurchase up to an additional $33.2 million of our common stock.

Accumulated Other Comprehensive Income (Loss)

Accumulated other comprehensive income (loss) consists of fair value adjustments associated with cash flow hedges, short-term investments and accumulated adjustments for net experience losses and prior service cost related to employee benefit plans. The following table presents the changes in accumulated other comprehensive income by component (in thousands) during the year ended December 31, 2016:



	For the Year Ended December 31, 2016
	Unrealized gain (loss) on cash flow hedges			Unrealized gain (loss) on short-term investments			Pension and other post- retirement benefits liability			Total
Beginning Balance	$	(81	)	$	6		$	(16,096	)	$	(16,171	)
Other comprehensive income before reclassifications	(32		)	(6		)	(760		)	(798		)
Amounts reclassed from accumulated other comprehensive income	81			—			1,012			1,093
Ending Balance	$	(32	)	$	—		$	(15,844	)	$	(15,876	)

Amounts reclassed from accumulated other comprehensive income (loss) related to cash flow hedges are included in interest expense in our Income Statements and amounts reclassed related to the pension and other post-retirement benefits liability are included in the computation of net periodic pension costs, at their before tax amounts.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
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-Subparagraph (SX 210.5-02(30))
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-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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-Glossary Preferred Stock
-URI http://asc.fasb.org/extlink&oid=6521494

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+ Details

Business Combinations

12 Months Ended

Dec. 31, 2016

Business Combinations [Abstract]

Business Combinations

NOTE D—BUSINESS COMBINATIONS

NBI Acquisition:

On August 16, 2016, we completed the acquisition of New Birmingham, Inc. (“NBI”), the ultimate parent company of NBR Sand, LLC (“NBR”), by acquiring all of the outstanding capital stock of NBI through the merger of New Birmingham Merger Corp., a Nevada corporation and wholly owned subsidiary of the Company, with and into NBI, followed immediately by the merger of NBI with and into NBI Merger Subsidiary II, Inc., a Delaware corporation and wholly owned subsidiary of the Company, which subsequently changed its name to Tyler Silica Company (the “NBI Acquisition”). NBR is a regional sand producer located near Tyler, Texas. The acquisition of NBI increased our regional frac sand product offering in our Oil & Gas Proppants segment.

The preliminary consideration paid to the stockholders of NBI at the closing of the NBI Acquisition consisted of $107.2 million of cash (net of $9.0 million cash acquired) and 2,630,513 shares of common stock. The calculation of the preliminary purchase price (in thousands, except shares) is as follows:




Cash consideration paid			$	116,165
Number of Holdings common shares delivered	2,630,513
Multiplied by closing market price per share of U.S. Silica common stock on August 16, 2016	$	40.51
Total value of Holdings common shares delivered			$	106,562
Less, cash acquired			$	(9,002	)
Total purchase price			$	213,725

The following table sets forth the preliminary allocation of the purchase price to the identifiable tangible and intangible assets acquired and liabilities assumed (in thousands):



Allocation of Purchase price:
Accounts receivable	$	2,680
Inventories	3,494
Other current assets	428
Income tax deposits	6,657
Property, plant and mine development	210,913
Identifiable intangible assets	1,600
Goodwill	86,228
Total assets acquired	312,000
Accounts payable, accrued expenses and other current liabilities	1,938
Deferred revenue	500
Notes payable	24,361
Capital lease liabilities	3,331
Asset retirement obligations	710
Deferred tax liabilities	67,435
Total liabilities assumed	98,275
Net assets acquired	$	213,725

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	$	1,600	15

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 regional frac sand markets and synergies expected to be achieved from integrating the operations of our operating subsidiary, U.S. Silica Company (“U.S. Silica”), and NBI. The goodwill amount is included in our Oil & Gas Proppants segment. Both customer relationships and goodwill are not expected to be deductible for tax purposes.

We incurred $1.4 million of acquisition-related charges which are included in selling, general and administrative expenses during the year ended December 31, 2016. Additionally, we incurred $1.7 million related to the inventory write-up values in cost of goods sold during the year ended December 31, 2016. Revenue and earnings for NBR after the acquisition date are not presented as the business was integrated into our operations subsequent to the acquisition and therefore impracticable to quantify.

Sandbox Acquisition:

On August 22, 2016, we completed the purchase of all of the outstanding units of membership interest of Sandbox Enterprises, LLC, a Texas limited liability company ("Sandbox" or the “Sandbox Acquisition”). Sandbox earns revenues from providing “last mile” transportation services to companies in the oil and gas industry. Sandbox has operations in Midland/Odessa, Texas; Morgantown, West Virginia; western North Dakota; northeast of Denver, Colorado; Oklahoma City, OK; and Cambridge, Ohio, where its major customers are located.

The preliminary consideration paid includes $69.5 million of cash (net of $1.3 million cash acquired) and 4,195,180 shares of our common stock. The calculation of preliminary purchase price (in thousands, except shares) is as follows:




Cash consideration paid			$	70,760
Number of Holdings common shares delivered	4,195,180
Multiplied by closing market price per share of U.S. Silica common stock on August 22, 2016	$	40.92
Total value of Holdings common shares delivered			$	171,667
Less, cash acquired			$	(1,306	)
Total purchase price			$	241,121

The following table sets forth a preliminary allocation of the purchase price to Sandbox’s identifiable tangible and intangible assets acquired and liabilities assumed (in thousands):



Allocation of Purchase price:	(in thousands)
Accounts receivable	$	13,392
Prepaid expenses and other	1,465
Property, plant and mine development	32,336
Identifiable intangible assets	120,144
Goodwill	86,100
Total assets acquired	253,437
Accounts payable	4,122
Deferred revenue	4,902
Accrued expenses and other current liabilities	3,292
Total liabilities assumed	12,316
Net assets acquired	$	241,121

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



	Approximate Fair Value		Estimated Useful Life
	(in thousands)		(in years)
Indefinite lived intangible assets - Trade names	$	17,844	Indefinite
Definite lived intangible assets - Technology and intellectual property	57,700		15
Definite lived intangible asset - Customer relationships	44,600		13
Total fair value of identifiable intangible assets	$	120,144

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 expected growth in frac sand demand at the wellhead and synergies expected to be achieved from integrating the operations of U.S. Silica and Sandbox. The goodwill amount is included in our Oil & Gas Proppants segment. Goodwill and all intangible assets identified above are expected to be deductible for tax purposes.

Our 2016 Income Statement included revenue of $31.0 million associated with Sandbox following the date of acquisition. Sandbox's impact on our net loss was not significant for the year ended December 31, 2016. We incurred $3.0 million of acquisition-related charges which are included in selling, general and administrative expenses on the Income Statement for the year ended December 31, 2016.

The cost related to the issuance of the 6,825,693 shares of common stock to complete the two acquisitions totaled $0.3 million, which is included in additional paid-in capital on our Condensed Consolidated Statements of Stockholders' Equity for the year ended December 31, 2016.

Both acquisitions were accounted for using the acquisition method of accounting. The purchase price and purchase price allocations for both Sandbox and NBI acquisitions are preliminary and subject to customary post-closing adjustments and changes in the fair value of assets and liabilities. The above estimated fair values of assets acquired and liabilities assumed are based on the information that was available as of the reporting date. We believe that the information provides a reasonable basis for estimating the fair values of the acquired assets and assumed liabilities, but the potential for measurement period adjustments exists based on our continuing review of matters related to the acquisitions. As a result, our final purchase price allocations may be significantly different than those reflected in the tables above. We expect to complete the purchase price allocations as soon as practicable, but no later than one year from the acquisition dates.

Combined Pro Forma Results

The results of NBI's and Sandbox’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 NBI Acquisition and Sandbox Acquisition had occurred on January 1, 2015, 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,
	2016			2015
Sales	$	615,552		$	753,287
Net income (loss)	$	(45,161	)	$	43,163
Basic earnings per share	$	(0.69	)	$	0.81
Diluted earnings per share	$	(0.69	)	$	0.81

- Definition

The entire disclosure for a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities. The disclosure may include leverage buyout transactions (as applicable).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Reference 14: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Publisher FASB
-Name Accounting Standards Codification
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+ Details

Accounts Receivable

12 Months Ended

Dec. 31, 2016

Receivables [Abstract]

Accounts Receivable

NOTE E—ACCOUNTS RECEIVABLE

At December 31, 2016 and 2015, accounts receivable (in thousands) consisted of the following:



	At December 31,
	2016			2015
Trade receivables	$	93,982		$	64,821
Less: Allowance for doubtful accounts	(7,042		)	(7,686		)
Net trade receivables	86,940			57,135
Other receivables	2,066			1,571
Total accounts receivable	$	89,006		$	58,706

Changes in our allowance for doubtful accounts (in thousands) during the years ended December 31, 2016 and 2015 are as follows:



	Allowance for Doubtful Accounts
	2016			2015
Balance at January 1,	$	7,686		$	10,429
Bad debt provision	(1,232		)	(290		)
Write-offs and recoveries	588			(2,453		)
Balance at December 31,	$	7,042		$	7,686

- Definition

The entire disclosure for claims held for amounts due a entity, excluding financing receivables. Examples include, but are not limited to, trade accounts receivables, notes receivables, loans receivables. Includes disclosure for allowance for credit losses.

+ References + Details

Property, Plant and Mine Development

12 Months Ended

Dec. 31, 2016

Property, Plant and Equipment [Abstract]

Property, Plant and Mine Development

NOTE G—PROPERTY, PLANT AND MINE DEVELOPMENT

At December 31, 2016 and 2015, property, plant and mine development (in thousands) consisted of the following:



	At December 31,
	2016			2015
Mining property and mine development	$	414,434		$	222,439
Asset retirement cost	8,062			9,889
Land	35,052			30,322
Land improvements	42,738			37,791
Buildings	52,178			51,280
Machinery and equipment	450,881			360,817
Furniture and fixtures	2,566			1,917
Construction-in-progress	43,790			56,130
	1,049,701			770,585
Accumulated depletion, depreciation and amortization	(266,388		)	(209,389		)
Total property, plant and mine development, net	$	783,313		$	561,196

At December 31, 2016, the aggregate cost of the machinery and equipment acquired under capital lease was $4.7 million, reduced by accumulated depreciation of $0.3 million. At December 31, 2015, we held no assets under a capital lease obligation.

During 2015, we wrote off $1.1 million of equipment due to discontinuation of certain industrial and specialty products. This amount is included in the depreciation, depletion and amortization expense on our Income Statements. The amount of interest costs capitalized in property, plant and equipment was $0.2 million, $0.5 million and $1.4 million for the years ended December 31, 2016, 2015 and 2014, respectively.

Debt and Capital Leases

12 Months Ended

Dec. 31, 2016

Debt Disclosure [Abstract]

Debt and Capital Leases

NOTE I—DEBT AND CAPITAL LEASES

At December 31, 2016 and 2015, debt (in thousands) consisted of the following:



	December 31, 2016			December 31, 2015
Senior secured credit facility:
Revolver expiring July 23, 2018 (5.25% at December 31, 2016 and 5% at December 31, 2015)	$	—		$	—
Term loan facility—final maturity July 23, 2020 (4% - 4.5% at December 31, 2016 and December 31, 2015)	494,175			499,275
Less: Unamortized original issue discount	(1,318		)	(1,696		)
Less: Unamortized debt issuance cost	(4,482		)	(5,874		)
Note payable secured by royalty interest (includes $3,053 unamortized fair value premium)	23,076			—
Customer note payable	1,787			—
Total debt	513,238			491,705
Less: current portion	(4,821		)	(3,330		)
Total long-term portion of debt	$	508,417		$	488,375

Revolving Line-of-Credit

We have a $50 million the Revolver, with zero drawn and $4.0 million allocated for letters of credit as of December 31, 2016, leaving $46.0 million available under the Revolver.

Debt Maturities

At December 31, 2016, contractual maturities of senior secured credit facility (in thousands) are as follows:



2017	$	5,100
2018	5,100
2019	5,100
2020	478,875
	$	494,175

On July 23, 2013, we refinanced our then existing senior secured debt by amending our Term Loan and replacing our then existing revolving line-of-credit. The Term Loan amendment refinanced our then existing senior debt by entering into a new $425 million senior secured credit facility, consisting of a $375 million Term Loan and the $50 million Revolver that may also be used for swingline loans (up to $5 million) or letters of credit (up to $20 million). The Term Loan amendment also, among other things, removed and amended certain financial and other covenants to provide additional operating flexibility, and lowered interest rates on borrowed amounts. The existing revolving line-of-credit was terminated. The Term Loan will expire on July 23, 2020 and the Revolver will expire on July 23, 2018. On December 5, 2014, we further increased our Term Loan by an additional $135 million to a total of approximately $502 million in accordance with the incremental borrowing feature in our senior secured credit facility.

Our senior secured credit facility is secured by a pledge of substantially all of our assets, including accounts receivable, inventory, property, plant and mine development, and a pledge of the equity interests in certain of our subsidiaries. The facility contains covenants that, among other things, govern our ability to create, incur or assume indebtedness and liens, to make acquisitions or investments, to sell assets and to pay dividends. This includes a restriction on the ability of our operating subsidiaries to make distributions to us to the extent that the incurrence ratio (as defined in the senior secured credit facility) after giving effect to the distribution is 3:1 or greater. The facility also requires us to maintain a consolidated total net 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 25% of the Revolver commitment. As of December 31, 2016 and December 31, 2015, we are in compliance with all covenants in accordance with our senior secured credit facility.

Note Payable Secured by Royalty Interest

In conjunction with the NBI Acquisition, 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:



2017	$	1,750
2018	1,750
2019	1,750
2020	1,750
2021	1,750

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 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 discount rate of 14%. As of December 31, 2016, the note payable has a balance of $23.1 million. The $0.6 million increase in this note payable amount is due to payment-in-kind interest.

Customer Note Payable

In connection with the NBI Acquisition, we assumed a customer note payable that was entered into by NBI. NBI entered into an amendment to a supply agreement effective January 1, 2016. Terms of the amended agreement call for repayment of $2.5 million at 0% interest, in equal monthly payments beginning January 1, 2016 for 60 months, or $0.5 million per year. Additionally, the principal of this note payable can be reduced via future product load credit. We discounted the required future cash payments and projected product load credit using an effective interest rate of 3.5% and recorded the note payable at $1.9 million on the acquisition date.

Capital Leases

We enter into financing arrangements from time to time to purchase machinery and equipment utilized in operations. At December 31, 2016, scheduled future minimum lease payments under capital lease obligations (in thousands) are as follows:



2017	$	2,315
2018	722
Total minimum lease payments	3,037
Less: amount representing interest	(83		)
Present value of minimum lease payments	2,954
Less: current portion of capital lease obligations	(2,237		)
Non-current portion of capital lease obligations	$	717

Deferred Revenue	12 Months Ended
Deferred Revenue	Dec. 31, 2016
Deferred Revenue Disclosure [Abstract]
Deferred Revenue	NOTE J—DEFERRED REVENUE On July 3, 2014, we received an advance of $100.0 million from a customer under a supply agreement which gives the customer the right to purchase certain products for a fixed price at certain volumes. The customer has an unsecured promissory note related to this deposit, which has been recorded as deferred revenue in the Balance Sheets. The unused portion of the deposit has a stated interest rate of 4.9% compounded quarterly. The deposit obligation and related interest are reduced as shipments occur with a portion of the sales price being received in cash and a smaller non-cash portion reducing first any accrued interest and then, to the extent available, any outstanding deposit. We can, through December 31, 2019, repay the unused deposit obligation at any time without penalty.

- Definition

The entire disclosure for deferred revenues at the end of the reporting period, and description and amounts of significant changes that occurred during the reporting period. Deferred revenue is a liability as of the balance sheet date related to a revenue producing activity for which revenue has not yet been recognized. Generally, an entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

+ References + Details

Fair Value Accounting

12 Months Ended

Dec. 31, 2016

Fair Value Disclosures [Abstract]

Fair Value Accounting

NOTE K—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, quote 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, 2016 and 2015 approximate their reported carrying values.

Short-Term Investments

In general, the fair value of our short-term investments is based on quoted prices for similar assets in active markets, or for identical assets or similar assets in markets in which there were fewer transactions (Level 2). Money market mutual funds are based on calculated net asset value and are reported in Level 1. Variable rate demand obligations underwritten and remarketed by a financial institution are priced at par value.

Long-Term Debt, Including Current Maturities

We believe that the fair values of our long-term debt, including current maturities, approximates their carrying values based on their effective interest rates compared to current market rates.

Derivative Instruments

The estimated fair value of our derivative assets (interest rate caps) 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 with 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, 2016, 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.

In accordance with the fair value hierarchy, the following table presents the fair value as of December 31, 2016 and 2015, respectively, of those assets (in thousands) that we measure at fair value on a recurring basis:



	December 31, 2016						December 31, 2015
	Level 1		Level 2		Total		Level 1		Level 2		Total
Short-term investments	$	—	$	—	$	—	$	1	$	21,848	$	21,849
Interest rate derivatives	—		72		72		—		—		—
Net asset	$	—	$	72	$	72	$	1	$	21,848	$	21,849

- 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

Short-Term Investments

12 Months Ended

Dec. 31, 2016

Investments, Debt and Equity Securities [Abstract]

Short-Term Investments

NOTE L—SHORT-TERM INVESTMENTS

At December 31, 2015, we segregated funds into designated accounts with investment brokers who managed our short-term investment portfolio. Those funds were held on an available-for-sale basis and are therefore reported at fair value on the balance sheet. In 2016, we liquidated our short-term investments and have no short-term investments as of December 31, 2016. The following table summarizes our available-for-sale short-term investments (in thousands) as of December 31, 2015:



	Aggregate Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
December 31, 2015
Money market mutual funds	$	1	$	—	$	—		$	1
Fixed income securities:
Certificates of deposit	10,535		—		(3		)	10,532
Commercial paper	5,689		19		—			5,708
Corporate notes and bonds	2,006		—		—			2,006
Government agencies	3,598		4		—			3,602
U.S. Treasuries	—		—		—			—
Variable rate demand obligations	—		—		—			—
Total available-for-sale investments	$	21,829	$	23	$	(3	)	$	21,849

- Definition

The entire disclosure for investments in certain debt and equity securities.

+ References + Details

Derivative Instruments

12 Months Ended

Dec. 31, 2016

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Instruments

NOTE M—DERIVATIVE INSTRUMENTS

Cash Flow Hedges of Interest Rate Risk

We enter into interest rate cap agreements in connection with the Term Loan to add stability to interest expense and to manage our exposure to interest rate movements. Interest rate caps designated as cash flow hedges involve the receipt of variable-rate amounts from a counterparty if interest rates rise above the strike rate on the contract in exchange for an upfront premium.

The following table summarizes the fair value of our derivative instruments (in thousands, except contract/notional amount). See Note K - Fair Value Accounting for additional disclosures regarding the estimated fair values of our derivative instruments at December 31, 2016, and 2015.



		December 31, 2016								December 31, 2015
	Maturity Date	Contract/Notional Amount			Carrying Amount		Fair Value		Maturity Date	Contract/Notional Amount			Carrying Amount		Fair Value
Interest rate cap agreement⁽¹⁾	2019	$	249	million	$	72	$	72	2016	$	252	million	$	—	$	—

⁽¹⁾Agreements limit the LIBOR floating interest rate base to 4%.

We have designated these contracts 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. During the year ended December 31, 2016 and 2015, we had no ineffectiveness for such contracts.

The following table summarizes the effect of derivatives instruments (in thousands) on our income statements and our consolidated statements of comprehensive income for the years ended December 31, 2016, 2015 and 2014.



	2016			2015			2014
Deferred losses from derivatives in OCI, beginning of period	$	(81	)	$	(134	)	$	(79	)
Loss recognized in OCI from derivative instruments	(32		)	—			(65		)
Loss reclassified from Accumulated OCI	81			53			10
Deferred losses from derivatives in OCI, end of period	$	(32	)	$	(81	)	$	(134	)

- Definition

The entire disclosure for derivative instruments and hedging activities including, but not limited to, risk management strategies, non-hedging derivative instruments, assets, liabilities, revenue and expenses, and methodologies and assumptions used in determining the amounts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6441202&loc=d3e80720-113993

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
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-Section 50
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+ Details

Equity-Based Compensation

12 Months Ended

Dec. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Equity-Based Compensation

NOTE N—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, 2016, we have 4,437,767 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 grants during the year ended December 31, 2016:



	Number of Shares		Weighted Average Exercise Price	Aggregate Intrinsic Value (in thousands)		Weighted Average Remaining Contractual Term in Years
Outstanding at December 31, 2015	1,307,067		24.61
Granted	—		—
Exercised	(326,884	)	14.76
Forfeited	(27,490	)	24.81
Outstanding at December 31, 2016	952,693		27.99	$	27,332	7.00 years
Exercisable at December 31, 2016	597,799		23.71	$	19,712	6.33 years

The total intrinsic value of stock options exercised was $7.6 million, $0.4 million, and $10.9 million for the years ended December 31, 2016, 2015 and 2014 respectively. Cash received from options exercised in 2016 was $4.8 million. The actual tax benefit realized for the tax deductions from option exercises totaled $2.9 million, $0.0 million, and $4.2 million for the years ended December 31, 2016, 2015 and 2014, respectively.

We recognized $3.0 million, $3.4 million, and $1.9 million of equity-based compensation expense related to these options during the years ended December 31, 2016, 2015 and 2014, respectively. As of December 31, 2016, there was $3.7 million of total unrecognized compensation expense related to these options, which is expected to be recognized over a weighted-average period of approximately 1.5 years.

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, 2016:



	Number of Shares		Grant Date Weighted Average Fair Value
Unvested, December 31, 2015	398,987		$	26.65
Granted	364,710		22.97
Vested	(180,419	)	26.28
Forfeited	(25,562	)	27.26
Unvested, December 31, 2016	557,716		$	24.33

We recognized $5.7 million, $3.9 million, and $2.2 million of equity-based compensation expense related to these restricted stock awards during the years ended December 31, 2016, 2015 and 2014 respectively. As of December 31, 2016, there was $9.5 million of total unrecognized compensation expense related to these restricted stock awards, which is expected to be recognized over a 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, 2016:



	Number of Shares		Grant Date Weighted Average Fair Value
Unvested, December 31, 2015	277,066		$	29.05
Granted	850,143		39.36
Vested	—		—
Forfeited	(163,596	)	33.30
Unvested, December 31, 2016	963,613		$	32.63

We recognized $3.3 million, ($3.4 million), and $3.4 million of compensation expense related to these performance share unit awards during the years ended December 31, 2016, 2015 and 2014 respectively. As of December 31, 2016, there was $17.6 million of estimated total unrecognized compensation expense related to these performance share unit awards, which is expected to be recognized over a period of 1.7 years.

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References + Details

Commitments and Contingencies

12 Months Ended

Dec. 31, 2016

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

NOTE O—COMMITMENTS AND CONTINGENCIES

Future Minimum Annual Commitments at December 31, 2016



Amounts in thousands Year ending December 31,	Operating Lease Minimum Rental Payments		Minimum Purchase Commitments
2017	$	55,525	$	20,739
2018	63,221		19,332
2019	56,171		17,590
2020	48,774		9,175
2021	42,824		3,450
Thereafter	114,905		12,800
Total future lease and purchase commitments	$	381,420	$	83,086

Operating Leases

We are obligated under certain operating leases for railroad cars, office space, mining property, mining/processing equipment and transportation and other equipment. Certain operating lease agreements include options to purchase the equipment for fair market value at the end of the original lease term. In general, the above leases include renewal options and provide that we pay for all utilities, insurance, taxes and maintenance. Expense related to operating leases and rental agreements for the years ended December 31, 2016, 2015 and 2014 totaled approximately $54.1 million, $48.2 million and $33.3 million, respectively.

Minimum Purchase Commitments

We enter into service agreements with our transload service providers 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.

Other Commitments and Contingencies

Our operating subsidiary, U.S. Silica, has been named as a defendant in various product liability claims alleging silica exposure causing silicosis. U.S. Silica was named as a defendant in two claims filed during the year ended December 31, 2016, no claims filed in 2015 and one claim filed in 2014. As of December 31, 2016, there were 74 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.

For periods prior to 1986, U.S. Silica had numerous insurance policies and an indemnity from a former owner that covered silicosis claims. In the fourth quarter of 2012, U.S. Silica settled all rights under the indemnity and its underlying insurance. The settlement was received during the first quarter of 2013. As a result of the settlement, the indemnity and related policies are no longer available to U.S. Silica and U.S. Silica will not seek reimbursement for any defense costs or claim payments. Other insurance policies, however, continue to remain available to U.S. Silica.

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, 2016 and 2015, other non-current assets included $0.3 million for insurance for third-party products liability claims. As of December 31, 2016 and 2015, other long-term obligations included $1.3 million and $1.5 million, respectively, in third-party products claims liability.

Additionally, during 2015, we received an unfavorable ruling in an arbitration proceeding as a result of exiting a toll manufacturing contract. The matter was settled and the settlement amount of $6.5 million was paid on June 9, 2015, which was included in selling, general and administrative expense in our Income Statement for the year ended December 31, 2015

Pension and Post-Retirement Benefits

12 Months Ended

Dec. 31, 2016

Compensation and Retirement Disclosure [Abstract]

Pension and Post-Retirement Benefits

NOTE P—PENSION AND POST-RETIREMENT BENEFITS

We maintain a single-employer noncontributory defined benefit pension plan covering certain employees. There have been no new entrants to the plan since May 2009 when the plan was frozen to all new employees. The plan provides 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 plan consistent with a goal of appropriate minimization of the unfunded projected benefit obligation. The pension plan uses a benefit level per year of service for covered hourly employees and a final average pay method for covered salaried employees. The plan uses 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 healthcare 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 maintain a Voluntary Employees’ Beneficiary Association trust that will be used to partially fund health care benefits for future retirees. Benefits are funded to the extent contributions are tax deductible, which under current legislation is limited. 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, 2016, 2015 and 2014:



	Years Ended December 31,
	2016			2015			2014
Service cost—benefits earned during the period	$	1,078		$	1,295		$	1,080
Interest cost	4,067			4,813			4,811
Expected return on plan assets	(5,495		)	(5,498		)	(5,146		)
Net amortization and deferral	1,592			2,665			1,037
Net pension benefit costs	$	1,242		$	3,275		$	1,782

Net post-retirement cost (in thousands) consisted of the following for the years ended December 31, 2016, 2015 and 2014:



	Years Ended December 31,
	2016			2015			2014
Service cost—benefits earned during the period	$	132		$	176		$	151
Interest cost	876			1,074			1,030
Expected return on plan assets	(1		)	(1		)	(4		)
Net amortization and deferral	—			281			—
Special termination benefit	21			48			—
Net post-retirement costs	$	1,028		$	1,578		$	1,177

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, 2016 and 2015 are as follows:



	Pension Benefits						Post-retirement Benefits
	2016			2015			2016			2015
Benefit obligation at January 1,	$	115,420		$	122,336		$	25,091		$	28,289
Service cost	1,078			1,295			132			176
Interest cost	4,067			4,813			876			1,074
Actuarial (gain) loss	1,640			(7,492		)	(802		)	(3,631		)
Benefits paid	(6,517		)	(6,106		)	(1,332		)	(1,288		)
Amendments	457			574			—			—
Special termination benefits	—			—			21			48
Other	—			—			407			423
Benefit obligation at December 31,	$	116,145		$	115,420		$	24,393		$	25,091
Fair value of plan assets at January 1,	$	84,716		$	90,897		$	17		$	19
Actual return on plan assets	5,651			(2,100		)	(3		)	(2		)
Employer contributions	—			2,025			925			864
Benefits paid	(6,517		)	(6,106		)	(1,332		)	(1,288		)
Other	—			—			407			424
Fair value of plan assets at December 31,	$	83,850		$	84,716		$	14		$	17
Plan assets less than benefit obligations at December 31 recognized as liability for pension and other post-retirement benefits	$	(32,295	)	$	(30,704	)	$	(24,379	)	$	(25,074	)

The accumulated benefit obligation for the defined benefit pension plans, which excludes the assumption of future salary increases, totaled $116.0 million and $115.3 million at December 31, 2016 and 2015, respectively.

The amendments in 2015 and 2014 reflect plan changes including increases in the benefit multiplier for certain participants and allowing eligible salaried and non-union hourly participants to have the option to receive a lump sum form of payment under certain conditions and specific benefit increases at several plant facilities, 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 $0.0 million at December 31, 2016 and $1.6 million, $1.6 million and $0.0 million at December 31, 2015. Future estimated annual benefit payments (in thousands) for pension and post-retirement benefit obligations at December 31, 2016 are as follows:



	Benefits
			Post-retirement
	Pension		Before Medicare Subsidy		After Medicare Subsidy
2017	$	6,824	$	1,570	$	1,429
2018	7,050		1,544		1,402
2019	7,201		1,521		1,379
2020	7,343		1,598		1,452
2021	7,419		1,676		1,528
2022-2026	38,158		8,627		7,839

Our best estimate of expected contributions to the pension and post-retirement medical benefit plans for the 2017 fiscal year are $2.1 million and $1.4 million, respectively.

The amounts in accumulated other comprehensive income expected to be recognized as components of net periodic benefit cost (in thousands) during the year ended December 31, 2016 are as follows:



	Benefits
	Pension		Post-retirement		Total
Net actuarial loss	$	1,372	$	—	$	1,372
Prior service cost	411		—		411
	$	1,783	$	—	$	1,783

The total amounts in accumulated other comprehensive income related to net actuarial loss, net of tax, for both plans was $13.8 million and $14.1 million as of December 31, 2016 and 2015, respectively. The total amounts in accumulated other comprehensive income related to prior service cost, net of tax, for both plans, was $1.8 million as of December 31, 2016 and 2015.

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



	Pension Benefits				Post-retirement Benefits
	2016		2015		2016		2015
Discount rate	4.2	%	4.5	%	4.2	%	4.5	%
Long-term rate of compensation increase	3.5	%	3.5	%	N/A		N/A
Long-term rate of return on plan assets	7.0	%	7.0	%	7.0	%	7.0	%
Health care cost trend rate:
Pre-65 initial rate/ultimate rate	N/A		N/A		7.3%/5.0%		7.8%/5.0%
Pre-65 ultimate year	N/A		N/A		—		—
Post-65 initial rate/ultimate rate	N/A		N/A		8.5%/5.0%		9.0%/5.0%
Post-65 ultimate year	N/A		N/A		2024/2025		2024/2025

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 Only Above Medium Curve.

In 2016, we changed the method utilized to estimate the service cost and interest cost components of net periodic benefit costs for our defined benefit pension and other post-retirement benefit plans. Historically, we estimated the service cost and interest cost components using a single weighted average discount rate derived from the yield curve used to measure the benefit obligation at the beginning of the period. We have elected to use a spot rate approach in the estimation of these components of benefit cost by applying the specific rates along the yield curve to the relevant projected cash flows, as we believe this provides a better estimate of service and interest costs. We consider this a change in estimate and, accordingly, have accounted for it prospectively starting in 2016. This change does not affect the measurement of our total benefit obligation.

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



	Pension Benefits and Post-retirement Benefits
	2016	2015
Healthy lives	RP-2014 mortality table, adjusted back to 2006 base rates, with generational mortality improvements using Scale MP-2016	RP-2014 mortality table, adjusted back to 2006 base rates, with generational mortality improvements using Scale MP-2015
Disabled lives	RP-2014 disabled retiree mortality table, adjusted back to 2006 base rates, with generational mortality improvements using Scale MP-2016	RP-2014 disabled retiree mortality table, adjusted back to 2006 base rates, with generational mortality improvements using Scale MP-2015

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	$	144	$	(120	)
Effect on post-retirement benefit obligation	2,827		(2,406		)

The major investment categories and their relative percentage of the fair value of total plan assets as invested at December 31, 2016, and 2015 are as follows:



	Pension Benefits				Post-retirement Benefits
	2016		2015		2016		2015
Equity securities	59.4	%	58.1	%	64.0	%	52.5	%
Debt securities	38.3	%	40.0	%	39.1	%	35.3	%
Cash	2.3	%	1.9	%	(3.1	)%	12.2	%

The fair values of the pension plan assets (in thousands) at December 31, 2016, by asset category, are as follows:



	Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	—	$	1,893	$	—	$	1,893
Mutual funds:
Diversified emerging markets	7,700		—		—		7,700
Foreign large blend	12,621		—		—		12,621
Large-cap blend	16,687		—		—		16,687
Mid-cap blend	8,674		—		—		8,674
Real estate	4,070		—		—		4,070
Fixed income securities:
Corporate notes and bonds	21,357		—		—		21,357
Government agencies	301		—		—		301
U.S. Treasuries	7,495		—		—		7,495
Mortgage-backed securities	—		2,022		—		2,022
Asset-backed securities	—		983		—		983
Insurance policies	—		—		47		47
Net asset	$	78,905	$	4,898	$	47	$	83,850

The fair values of the pension plan assets (in thousands) at December 31, 2015, by asset category, are as follows:



	Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	—	$	1,635	$	—	$	1,635
Mutual funds:
Diversified emerging markets	6,890		—		—		6,890
Foreign large blend	13,111		—		—		13,111
Large-cap blend	16,855		—		—		16,855
Mid-cap blend	7,769		—		—		7,769
Real estate	4,369		—		—		4,369
Fixed income securities:
Corporate notes and bonds	22,559		—		—		22,559
Government agencies	607		—		—		607
U.S. Treasuries	5,384		—		—		5,384
Mortgage-backed securities	—		3,111		—		3,111
Asset-backed securities	—		2,375		—		2,375
Insurance policies	—		—		51		51
Net asset	$	77,544	$	7,121	$	51	$	84,716

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

2016

2015

2016

2015

2014

LIUNA

52-6074345/001

Red

Yes

167

182

149

Yes

5/31/2017

IUOE

36-6052390/001

Green

7/29/2018

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 in any of the three years ended December 31, 2016. 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 also contribute an employee match of 25 cents, for each dollar contributed by an employee, up to 8% of their earnings. For certain employees, we make a profit sharing match up to 25 cents, based on financial performance, for each dollar contributed up to 8% of their earnings. Finally, for some employees, we make a catch-up match of 25 cents for each dollar of catch-up contributions. Contributions were $2.4 million, $2.8 million and $2.1 million for the years ended December 31, 2016, 2015 and 2014, respectively.

Income Taxes

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Income Taxes

NOTE Q—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.

The expense or benefit for income taxes (in thousands) consisted of the following for the years ended December 31, 2016, 2015 and 2014:



	Years Ended December 31,
	2016			2015			2014
Current:
Federal	$	60		$	(170	)	$	(34,790	)
State	(274		)	1,448			(4,835		)
	$	(214	)	$	1,278		$	(39,625	)
Deferred:
Federal	32,944			7,439			(308		)
State	3,959			3,034			2,750
	$	36,903		$	10,473		$	2,442
Income tax benefit (expense)	$	36,689		$	11,751		$	(37,183	)

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, 2016 and 2015 consisted of the following:



	At December 31,
	2016			2015
Gross deferred tax assets:
Net operating loss carry forward and state tax credits	$	65,022		$	39,280
Pension and post-retirement benefit costs	22,920			22,577
Alternative minimum tax credit carry forward	19,431			19,049
Property, plant and equipment	6,112			6,657
Accrued expenses	6,752			3,765
Inventories	4,362			6,425
Third-party products liability	511			568
Stock-based compensation expense	5,576			3,365
Note payable	4,009			—
Other	5,458			5,373
Total deferred tax assets	$	140,153		$	107,059
Gross deferred tax liabilities:
Land and mineral property basis difference	$	(126,315	)	$	(63,488	)
Fixed assets and depreciation	(61,531		)	(54,913		)
Intangibles	(2,260		)	(8,049		)
Other	(122		)	(122		)
Total deferred tax liabilities	$	(190,228	)	$	(126,572	)
Net deferred tax liabilities	$	(50,075	)	$	(19,513	)

We have federal net operating loss carry forwards of approximately $170.4 million at December 31, 2016. The losses will expire in years 2027 through 2036. Approximately $69.0 million of the losses are subject to an annual limitation under Internal Revenue Code Section 382, but are expected to be fully realized.

At December 31, 2016 and 2015, we have an alternative minimum tax credit carry forward of approximately $19.4 million and $19.0 million, respectively. The credit carry forward may be carried forward indefinitely to offset any excess of regular tax liability over alternative minimum tax liability subject to certain limitations.

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, 2016 or December 31, 2015 and do not expect this to change significantly within the next twelve months. Tax returns filed with the IRS for the years 2013 through 2015 along with tax returns filed with numerous state entities remain subject to examination.

The income tax expense or 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, 2016, 2015 and 2014 due to the following:



	Years Ended December 31,
	2016			2015			2014
Income tax benefit (expense) computed at U.S. federal statutory rate	$	27,211		$	(41	)	$	(55,553	)
Decrease (increase) resulting from:
Statutory depletion	4,734			8,918			15,548
Prior year tax return reconciliation	435			393			1,018
State income taxes, net of federal benefit	2,369			1,370			(3,416		)
Domestic production deduction	—			—			3,911
Equity compensation	2,003			—			—
Other, net	(63		)	1,111			1,309
Income tax benefit (expense)	$	36,689		$	11,751		$	(37,183	)

Obligations Under Guarantees	12 Months Ended
Obligations Under Guarantees	Dec. 31, 2016
Guarantees [Abstract]
Obligations Under Guarantees	NOTE R—OBLIGATIONS UNDER GUARANTEES We have indemnified Travelers Casualty and Surety Company of America (“Travelers”) against any loss Travelers may incur in the event that holders of surety bonds, issued on behalf of us by Travelers, execute the bonds. As of December 31, 2016, Travelers had $10.5 million in bonds outstanding for us. The majority of these bonds ($10.1 million) relate to reclamation requirements issued by various governmental authorities. Reclamation bonds remain outstanding until the mining area is reclaimed and the authority issues a formal release. The remaining bonds relate to such indefinite purposes as licenses, permits, and tax collection.

Segment Reporting

12 Months Ended

Dec. 31, 2016

Segment Reporting [Abstract]

Segment Reporting

NOTE S—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.

An operating segment’s performance is primarily evaluated based on segment contribution margin, which excludes certain corporate costs not associated with the operations of the segment. These corporate costs are separately stated below and include costs that are related to functional areas such as operations management, corporate purchasing, accounting, treasury, information technology, legal and human resources. We believe that segment contribution margin, as defined above, is an appropriate measure for evaluating the operating performance of our segments. However, this measure should be considered in addition to, not a substitute for, or superior to, income from operations or other measures of financial performance prepared in accordance with generally accepted accounting principles. The other accounting policies of each of the two reporting segments are the same as those in Note B - Summary of Significant Accounting Policies.

In the Oil & Gas Proppants segment, we serve the oil and gas recovery market providing 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 natural gas and oil from the wells.

The Industrial & Specialty Products segment consists of over 215 products and materials used in a variety of industries including, container glass, fiberglass, specialty glass, flat glass, building products, fillers and extenders, foundry products, chemicals, recreation products and filtration products.

The following table presents sales and segment contribution margin (in thousands) for the reporting segments and other operating results not allocated to the reported segments for the years ended December 31, 2016, 2015 and 2014:



	Years Ended December 31,
	2016			2015			2014
Sales:
Oil & Gas Proppants	$	362,550		$	430,435		$	662,770
Industrial & Specialty Products	197,075			212,554			213,971
Total sales	$	559,625		$	642,989		$	876,741
Segment contribution margin:
Oil & Gas Proppants	$	11,445		$	88,928		$	256,137
Industrial & Specialty Products	78,988			70,137			61,102
Total segment contribution margin	$	90,433		$	159,065		$	317,239
Operating activities excluded from segment cost of goods sold	(8,103		)	(11,142		)	(7,082		)
Selling, general and administrative	(67,727		)	(62,777		)	(88,971		)
Depreciation, depletion and amortization	(68,134		)	(58,474		)	(45,019		)
Interest expense	(27,972		)	(27,283		)	(18,202		)
Other income, net, including interest income	3,758			728			758
Income tax benefit (expense)	$	36,689		11,751			(37,183		)
Net income (loss)	$	(41,056	)	$	11,868		$	121,540

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. Goodwill of $241.0 million has been allocated to these segments with $220.3 million assigned to Oil & Gas Proppants and $20.7 million to Industrial & Specialty Products.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8981-108599

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e9038-108599

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8971-108599

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8595-108599

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8380-108599

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8933-108599

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 26
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8844-108599

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 35
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8984-108599

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e9031-108599

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e9054-108599

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8538-108599

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 29
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8864-108599

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8924-108599

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8906-108599

+ Details

Unaudited Supplementary Data

12 Months Ended

Dec. 31, 2016

Quarterly Financial Information Disclosure [Abstract]

Unaudited Supplementary Data

NOTE T—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, 2016 and 2015. 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. The income tax benefit amounts for 2016 first quarter and second quarter include the impacts from the early adoption of ASU 2016-09 discussed in Note B - Summary of Significant Accounting Policies.



	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
2016:	(Unaudited)
Sales	$	122,510		$	116,994		$	137,748		$	182,373
Cost of goods sold (excluding depreciation, depletion and amortization)	106,751			102,707			119,426			148,411
Operating expenses
Selling, general and administrative	15,503			14,585			18,472			19,167
Depreciation, depletion and amortization	14,556			15,209			17,175			21,194
	$	30,059		$	29,794		$	35,647		$	40,361
Operating loss	(14,300		)	(15,507		)	(17,325		)	(6,399		)
Other income (expense)
Interest expense	(6,643		)	(6,647		)	(6,684		)	(7,998		)
Other income, net, including interest income	1,790			608			493			867
	$	(4,853	)	$	(6,039	)	$	(6,191	)	$	(7,131	)
Loss before income taxes	(19,153		)	(21,546		)	(23,516		)	(13,530		)
Income tax benefit	8,150			9,774			12,177			6,588
Net loss	$	(11,003	)	$	(11,772	)	$	(11,339	)	$	(6,942	)
Loss per share, basic	$	(0.20	)	$	(0.19	)	$	(0.17	)	$	(0.09	)
Loss per share, diluted	$	(0.20	)	$	(0.19	)	$	(0.17	)	$	(0.09	)
Weighted average shares outstanding, basic	54,470			63,417			66,676			75,539
Weighted average shares outstanding, diluted	54,470			63,417			66,676			75,539
Dividends declared per share	$	0.06		$	0.06		$	0.06		$	0.06

	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
2015:	(Unaudited)
Sales	$	203,958		$	147,511		$	155,408		$	136,112
Cost of goods sold (excluding depreciation, depletion and amortization)	138,653			117,200			122,599			116,614
Operating expenses
Selling, general and administrative	26,961			6,575			13,559			15,682
Depreciation, depletion and amortization	13,243			13,695			15,158			16,378
	$	40,204		$	20,270		$	28,717		$	32,060
Operating income (loss)	25,101			10,041			4,092			(12,562		)
Other income (expense)
Interest expense	(6,836		)	(6,928		)	(6,684		)	(6,835		)
Other income (loss), net, including interest income	11			498			309			(90		)
	$	(6,825	)	$	(6,430	)	$	(6,375	)	$	(6,925	)
Income before income taxes	18,276			3,611			(2,283		)	(19,487		)
Income tax benefit (expense)	(3,453		)	6,342			4,695			4,167
Net income (loss)	$	14,823		$	9,953		$	2,412		$	(15,320	)
Earnings (loss) per share, basic	$	0.28		$	0.19		$	0.05		$	(0.29	)
Earnings (loss) per share, diluted	$	0.28		$	0.18		$	0.04		$	(0.29	)
Weighted average shares outstanding, basic	53,416			53,303			53,321			53,323
Weighted average shares outstanding, diluted	53,869			53,857			53,742			53,323
Dividends declared per share	$	0.13		$	0.13		$	0.13		$	0.06

Parent Company Financials

12 Months Ended

Dec. 31, 2016

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Parent Company Financials

NOTE U—PARENT COMPANY FINANCIALS

U.S. SILICA HOLDINGS, INC.

(PARENT COMPANY ONLY)

CONDENSED BALANCE SHEETS



	December 31,
	2016			2015
	(in thousands)
ASSETS
Current Assets:
Cash and cash equivalents	$	534,378		$	58,579
Short-term investments	—			21,849
Total current assets	534,378			80,428
Investment in subsidiaries	854,860			417,462
Total assets	$	1,389,238		$	497,890
LIABILITIES AND STOCKHOLDERS’ EQUITY
Current Liabilities:
Accrued expenses and other current liabilities	$	461		$	107
Dividends payable	5,222			3,453
Due to affiliates	110,265			110,159
Total current liabilities	115,948			113,719
Deferred income taxes, net	—			4
Total liabilities	115,948			113,723
Stockholders’ Equity:
Preferred stock	—			—
Common stock	811			539
Additional paid-in capital	1,129,051			194,670
Retained earnings	163,173			220,974
Treasury stock, at cost	(3,869		)	(15,845		)
Accumulated other comprehensive loss	(15,876		)	(16,171		)
Total stockholders’ equity	1,273,290			384,167
Total liabilities and stockholders’ equity	$	1,389,238		$	497,890

U.S. SILICA HOLDINGS, INC.

(PARENT COMPANY ONLY)

CONDENSED STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS)



	Year Ended December 31,
	2016			2015			2014
	(in thousands, except per share amounts)
Revenue	$	—		$	—		$	—
Cost of revenue	—			—			—
Operating expenses
Selling, general and administrative	184			185			184
Other	10			19			—
	194			204			184
Operating loss	(194		)	(204		)	(184		)
Other income (expense)
Interest income	1,046			262			278
Early extinguishment of debt	—			—			—
Other income, net, including interest income	—			1			—
	1,046			263			278
Income before income taxes and equity in net earnings of subsidiaries	852			59			94
Income tax benefit (expense)	(344		)	(24		)	(38		)
Income before equity in net earnings of subsidiaries	508			35			56
Equity in earnings of subsidiaries, net of tax	(41,564		)	11,833			121,484
Net income (loss)	(41,056		)	11,868			121,540
Other comprehensive income (loss), net of deferred income taxes:
Unrealized gain (loss) on investments (net of tax of ($4), $29, and ($8) for 2016, 2015, and 2014, respectively)	(6		)	47			(14		)
Unrealized loss on derivatives, (net of tax of $29, $34 and ($32) for 2016, 2015 and 2014, respectively)	49			53			(55		)
Pension and post-retirement liability (net of tax of $152, $2,469, and ($9,678) for 2016, 2015 and 2014, respectively)	252			3,547			(15,732		)
Other comprehensive income (loss), net of deferred income taxes	295			3,647			(15,801		)
Comprehensive income (loss) attributable to U.S. Silica Holdings, Inc.	$	(40,761	)	$	15,515		$	105,739

U.S. SILICA HOLDINGS, INC.

(PARENT COMPANY ONLY)

CONDENSED STATEMENT OF STOCKHOLDERS' EQUITY



													Accumulated
						Additional				Retained			Other			Total
	Par		Treasury			Paid-In				Earnings-			Comprehensive			Stockholders'
	Value		Stock			Capital				Present			Income (Loss)			Equity
Balance at January 1, 2014	$	534	$	—		$	174,799			$	137,978		$	(4,017	)	$	309,294
Net income	—		—			—				121,540			—			121,540
Unrealized loss on derivatives	—		—			—				—			(55		)	(55		)
Unrealized loss on short-term investments	—		—			—			—	—			(14		)	(14		)
Pension and post-retirement liability	—		—			—				—			(15,732		)	(15,732		)
Cash dividend declared ($0.500 per share)	—		—			—				(26,967		)	—			(26,967		)
Common stock-based compensation plans activity:
Equity-based compensation	—		—			7,487				—			—			7,487
Excess tax benefit from equity compensation	—		—			3,813				—			—			3,813
Proceeds from options exercised	4		572			4,987				—			—			5,563
Shares withheld for employee taxes related to
vested restricted stock and stock units	1		(615		)	—				—			—			(614		)
Repurchase of common stock	—		(499		)	—				—			—			(499		)
Balance at December 31, 2014	539		(542		)	191,086				232,551			(19,818		)	403,816
Net income	—		—			—				11,868			—			11,868
Unrealized gain on derivatives	—		—			—				—			53			53
Unrealized gain on short-term investments	—		—			—				—			47			47
Pension and post-retirement liability	—		—			—				—			3,547			3,547
Cash dividend declared ($0.438 per share)	—		—			—				(23,445		)	—			(23,445		)
Common stock-based compensation plans activity:
Equity-based compensation	—		—			3,857				—			—			3,857
Proceeds from options exercised	—		744			(271		)		—			—			473
Shares withheld for employee taxes related to
vested restricted stock and stock units	—		(792		)	(2		)		—			—			(794		)
Repurchase of common stock	—		(15,255		)	—				—			—			(15,255		)
Balance at December 31, 2015	539		(15,845		)	194,670				220,974			(16,171		)	384,167
Net loss	—		—			—				(41,056		)	—			(41,056		)
Issuance of common stock (stock offerings net of issuance costs of $25,732)	272		—			931,016				—			—			931,288
Unrealized gain on derivatives	—		—			—				—			49			49
Unrealized loss on short-term investments	—		—			—				—			(6		)	(6		)
Pension and post-retirement liability	—		—			—				—			252			252
Cash dividend declared ($0.25 per share)	—		—			—				(16,893		)	—			(16,893		)
Common stock-based compensation plans activity:
Equity-based compensation	—		—			12,107				—			—			12,107
Excess tax benefit from equity-based compensation	—		—			—				148			—			148
Proceeds from options exercised	—		8,465			(3,640		)		—			—			4,825
Issuance of restricted stock	—		1,437			(1,437		)		—			—			—
Shares withheld for employee taxes related to
vested restricted stock and stock units	—		2,074			(3,665		)		—			—			(1,591		)
Balance at December 31, 2016	$	811	$	(3,869	)	$	1,129,051			$	163,173		$	(15,876	)	$	1,273,290

U.S. SILICA HOLDINGS, INC.

(PARENT COMPANY ONLY)

CONDENSED STATEMENT OF CASH FLOWS



	Year Ended December 31,
	2016			2015			2014
	(in thousands)
Operating activities:
Net income (loss)	$	(41,056	)	$	11,868		$	121,540
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Undistributed (Income) loss from equity method investment, net	41,564			(11,833		)	(121,484		)
Other	(30		)	(195		)	(213		)
Changes in assets and liabilities, net of effects of acquisitions:
Accounts payable and accrued liabilities	353			29			36
Net cash provided by (used in) operating activities	831			(131		)	(121		)
Investing activities:
Proceeds from sales and maturities of short-term investments	21,872			53,568			—
Investment in subsidiary	(188,177		)	—			—
Net cash provided by (used in) investing activities	(166,305		)	53,568			—
Financing activities:
Dividends paid	(15,125		)	(26,797		)	(26,871		)
Repurchase of common stock	—			(15,255		)	(499		)
Proceeds from options exercised	4,603			473			5,563
Tax payments related to shares withheld for vested restricted stock and stock units	(1,590		)	(794		)	(614		)
Issuance of common stock (secondary offering)	678,791			—			—
Issuance of treasury stock	221			—			—
Costs of common stock issuance	(25,733		)	—			—
Net financing activities with subsidiaries	106			223			211
Net cash provided by (used in) financing activities	641,273			(42,150		)	(22,210		)
Net increase in cash and cash equivalents	475,799			11,287			(22,331		)
Cash and cash equivalents, beginning of period	58,579			47,292			69,623
Cash and cash equivalents, end of period	$	534,378		$	58,579		$	47,292
Non-cash financing activities:
Supplemental cash flow information:
Cash paid (received) during the period for:
Interest	$	(1,046	)	$	(263	)	$	(278	)
Non-cash transactions
Common stock issued for business acquisitions	$	278,229		$	—		$	—

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 senior credit facility, as discussed in Note I - Debt and Capital Leases to the audited consolidated 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.

- Definition

The entire disclosure for condensed financial information, including the financial position, cash flows, and the results of operations of the registrant (parent company) as of the same dates or for the same periods for which audited consolidated financial statements are being presented. Alternatively, the details of this disclosure can be reported by the specific parent company taxonomy elements, indicating the appropriate date and period contexts in an instance document.

+ References + Details

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2016
Accounting Policies [Abstract]
Basis of Presentation and Consolidation	Basis of Presentation and Consolidation The accompanying Consolidated Financial Statements (the “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 Financial Statements have been included. Such adjustments are of a normal, recurring nature. We have reclassified certain immaterial amounts in the prior years’ operating activities section section of the consolidated statement of cash flows to conform to the current year presentation. In order to make this report easier to read, we refer throughout 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 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”). For the periods presented herein, we have identified no entities over which we maintain any level of control that would qualify for consolidation under ASC guidance.
Use of Estimates and Assumptions	Use of Estimates and Assumptions The preparation of the 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 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 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 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; 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.
Revenue Recognition	Revenue Recognition We derive most of our sales by mining and processing minerals that our customers purchase for various uses. Our sales are primarily a function of the price per ton and the number of tons sold. The amount invoiced reflects product, transportation and additional services as applicable, such as storage, transloading the product from railcars to trucks and last mile logistics to the customer site. Revenue is recognized from a sale when persuasive evidence of an arrangement exists, the price is fixed and determinable, the product has been delivered, legal title has been transferred to the customer or services are completed and collection of the sale is reasonably assured. Amounts received from customers in advance of revenue recognition are deferred as liabilities. We primarily sell our products under short-term price agreements or at prevailing market rates. For a limited number of customers, we sell under long-term, competitively-bid take-or-pay supply agreements. As of December 31, 2016, we had seven take-or-pay supply agreements in the Oil & Gas Proppants segment with initial terms expiring between 2017 and 2019. 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 that our customers will pay for each product. Prices under these agreements are generally fixed and subject to upward adjustment in response to certain cost increases. Some of these existing agreements are under active 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 take-or-pay supply agreements. We invoice the majority of our clients on a per shipment basis, although for some larger customers, we consolidate invoices weekly or monthly. Standard terms are net 30 days, although extended terms are offered in competitive situations. Sales and other transaction taxes imposed by government entities are reported on a net basis.
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 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. Checks we issued but have not cleared our bank accounts frequently result in book overdraft balances. In 2015, we changed the presentation of book overdraft from being classified as a liability to a reduction to our cash and cash equivalents.
Accounts Receivable	Accounts Receivable The majority of our accounts receivable are due from companies in the oil and natural gas drilling, glass, building products, filler and extenders, foundries and other major industries. Our ten largest customers accounted for approximately 52%, 56%, and 57% of sales in the years ended December 31, 2016, 2015 and 2014, respectively. Sales to our largest customer, Halliburton Company, which is an Oil & Gas Proppants customer, accounted for 13% of our total revenues during the year ended December 31, 2016. No other customer accounted for 10% or more of our total revenues. 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 and silica and other industrial sand available for shipment, as well as spare parts and supplies for routine facility maintenance. We value inventory at the lower of cost or net realizable value. Cost is determined using the first-in, first-out and average cost methods. Costs of our raw stockpiles and silica and other industrial sand inventories 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 life 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 has 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. 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 reclamation obligations. 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. In connection with our annual review of our reclamation obligations, we have determined that some of our estimates required revision due primarily to the additions of new plant and transload facilities and other changes in cost estimates and settlement dates at various sites. These additions and changes in estimates resulted in an additional $(2.1) million and $0.2 million of asset retirement obligations in 2016 and 2015, respectively.
Impairment or Disposal of Property, Plant and Mine Development	Impairment or Disposal of Property, Plant and Mine Development 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. 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.
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 was acquired in connection with our Sandbox acquisition and mainly consists of patents and technology. It is amortized on a straight-line basis over an average useful life of 15 years. As of December 31, 2016, the gross carrying amount of the intellectual property intangible asset was $58.7 million with accumulated amortization of $1.4 million. During the year ended December 31, 2016, we capitalized $0.9 million in legal costs and patent filing costs. As of December 31, 2016, the remaining useful life was 14.6 years. The estimated annual amortization in each of the next five years is $3.8 million. Amortization expense for intellectual property was $1.4 million for the year ended December 31, 2016. Customer relationships are amortized on a straight-line basis over their useful life of 20, 15 or 13 years. We acquired additional customer relationships in connection with our NBI and Sandbox acquisitions during the year ended December 31, 2016. As of December 31, 2016, the gross carrying amount of the customer relationships intangible asset was $55.7 million with accumulated amortization of $4.8 million. As of December 31, 2016, the weighted average remaining useful life of our customer relationships was 13.0 years. The estimated annual amortization in each of the next five years is $4.0 million. Amortization expense was $1.8 million, $0.5 million and $0.4 million for the years ended December 31, 2016, 2015 and 2014, respectively. Goodwill represents the excess of purchase price over the fair value of net assets from business acquisitions. Goodwill and trade names are reviewed for impairment annually as of October 31 or more frequently whenever events or circumstances change that would more likely than not reduce the fair value of those assets. 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 comparison of the fair value with the carrying amount, including goodwill. If this comparison reflects impairment, then the loss would be measured as the excess of recorded goodwill, or other intangible assets with indefinite lives, over its implied fair value. Implied fair value is the excess of our fair value over the fair value of all recognized and unrecognized assets and liabilities. As of December 31, 2016, our qualitative assessment did not indicate that it was more likely than not that an impairment had occurred.
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 (the “Term Loan”) and the straight-line method for our revolving line-of-credit (the "Revolver"). Debt issuance costs related to long-term debt are reflected as direct deduction from the carrying amount of the debt. Amortization included in interest expense was $1.4 million, $1.4 million and $0.9 million for the years ended December 31, 2016, 2015 and 2014, respectively.
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. 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. For December 31, 2016 and 2015, our self-insurance reserves totaled $5.3 million and $5.7 million, respectively, and $1.3 million and $1.8 million was classified as current
Equity-based Compensation	Our expected forfeiture rate is the estimated percentage of options granted that are expected to be forfeited or canceled on an annual basis before becoming fully vested. 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. Equity-based Compensation We recognize the cost of employee services rendered in exchange for awards of equity instruments, including stock options, restricted stock, restricted stock units and performance share units. Vesting of restricted stock and restricted stock units is based on the individual continuing to render service over a three year vesting schedule. 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. During the year ended December 31, 2016, we granted 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 the three year period from January 1, 2016 through December 31, 2018. 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. The 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 options granted, we estimate the fair value of each grant using the Black-Scholes option-pricing model. The weighted-average fair value per share of options granted during the years ended December 31, 2015 and 2014 was $13.11 and $19.37, respectively. The fair value of stock options granted have been calculated based on the exercise price of the option and the following assumptions, which are evaluated and revised, as necessary, to reflect market conditions and experience. There were no options granted during the year ended December 31, 2016.
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.
Earnings per Share	Earnings per Share Basic and diluted earnings per share is presented for net income (loss). 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. In accordance with the applicable accounting guidance for calculating earnings per share, we did not include in our calculation of diluted earnings per share for the applicable periods stock options where the exercise prices were greater than the average market prices.
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, unrealized gain or loss on our short term investments and the effective portion of changes in fair value of derivative instruments that qualify as cash flow hedges.
Short-term Investments	Short-term Investments Our short-term investments consist of fixed income securities that have been classified and accounted for as available-for-sale. We determine the appropriate classification of our investments at the time of purchase and reevaluate the designations at each balance sheet date. We classify these securities as either short-term or long-term based on each instrument’s underlying contractual maturity date. Fixed income securities with maturities of 12 months or less are classified as short-term and fixed income securities with maturities greater than 12 months are classified as long-term. These investments are carried at fair value, with the unrealized gains and losses, net of taxes, reported as a separate component of accumulated other comprehensive income. The cost of securities sold is based upon the specific identification method. We typically invest in highly-rated securities, and our investment policy generally limits the amount of credit exposure to any one issuer. The policy requires investments generally to be investment grade, with the primary objective of minimizing the potential risk of principal loss. Fair values were determined for each individual security in the investment portfolio. When evaluating an investment for other-than-temporary impairment, we review factors such as the length of time and extent to which fair value has been below its cost basis, the financial condition of the issuer and any changes thereto, changes in market interest rates, and our intent to sell, or whether it is more likely than not we will be required to sell, the investment before recovery of the investment’s cost basis. As of December 31, 2015, we considered any losses in our short-term investment portfolio to be temporary in nature and did not consider any of our investments other-than-temporarily impaired. All short-term investments have matured as of December 31, 2016.
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 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. Additional disclosures for derivative instruments are presented in Note M to these financial statements.
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.
Recently Adopted and Issued Accounting Pronouncements	Recently Adopted Accounting Pronouncements In April 2015, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2015-03, Interest-Imputation of Interest, which simplifies presentation of debt issuance costs. The new standard requires that debt issuance costs be presented in the balance sheet as a direct deduction from the carrying amount of debt liability, consistent with debt discounts or premiums. The new standard was effective for financial statements issued for fiscal years beginning after December 15, 2015, and interim periods within fiscal years beginning after December 15, 2016. Early adoption of the amendments in this Update is permitted for financial statements that have not been previously issued. We have elected to adopt the standard early and have presented debt issuance costs as a direct deduction from the carrying amount of debt on our Balance Sheets as of December 31, 2016 and December 31, 2015. In November 2015, the FASB issued ASU 2015-17, Income Taxes - Balance Sheet Classification of Deferred Taxes, which will require the presentation of deferred tax liabilities and assets be classified as non-current on balance sheets. The amendments in this update are effective for financial statements issued for annual periods beginning after December 15, 2016, and interim periods within those annual periods. Early application is permitted for all entities as of the beginning of an interim or annual reporting period. We have elected to early adopt this guidance prospectively as of December 31, 2015. The adoption only impacted deferred tax presentation on our Balance Sheets and related disclosure. No prior periods were retrospectively adjusted. In July 2015, the FASB issued ASU 2015-11, Simplifying the Measurement of Inventory. The new standard requires an entity to measure most inventory at the lower of cost and net realizable value, thereby simplifying the current guidance under which an entity must measure inventory at the lower of cost or market. The new standard will not apply to inventories that are measured using either the last-in, first-out (LIFO) method or the retail inventory method. This Update is effective for public entities for financial statements issued for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years; early application is permitted. We elected to prospectively early adopt the standard effective January 1, 2016 and have measured our inventory at the lower of cost and net realizable value on our Balance Sheet. The impacts of the early adoption of this Update on our Financial Statements are not significant. In March 2016, the FASB issued ASU 2016-09, "Compensation-Stock Compensation." The update requires that excess tax benefits and deficiencies be recorded in the income statement when the awards vest or are settled. It also eliminates the requirement that excess tax benefits be realized (reduce cash taxes payable) before being recognized. Previously, an entity could not recognize excess tax benefits if the tax deduction increased a net operating loss ("NOL") or tax credit carryforward. The updated standard no longer requires cash flows related to excess tax benefits to be presented as a financing activity separate from other income tax cash flows. The update also allows the employer to repurchase more of an employee's shares for tax withholding purposes without triggering liability accounting, clarifies that all cash payments to taxing authorities made on an employee's behalf for withheld shares should be presented as a financing activity on the statement of cash flows, and provides for an accounting policy election to account for forfeitures as they occur. The update is effective for annual periods beginning after December 15, 2016 and interim periods within those annual periods and permits early adoption. We elected to early adopt this update during the three months ended September 30, 2016, which requires any adjustments to be reflected as of January 1, 2016. This resulted in the recognition of excess tax benefits on our Balance Sheet that were previously not recognized, as the benefits would have increased our NOL or tax credit carryforwards. The recognition decreased net deferred tax liability by $0.1 million and $2.2 million as of January 1, 2016 and December 31, 2016, respectively. Retained earnings on January 1, 2016 was increased accordingly by $0.1 million. In addition, we will recognize excess tax benefits or deficiencies in the provision for income taxes rather than paid-in capital for 2016 and future periods. Adoption of the update resulted in the reduction in the provision for income taxes of $2.2 million for the year ended December 31, 2016. The effect of the adoption of this update on our previously reported income tax provision on our Income Statement was a decrease in tax benefit of $0.3 million for the three months ended March 31, 2016 and an increase in tax benefit of $0.2 million for the three months ended June 30, 2016, respectively. We elected to include excess tax benefits as operating activities in the Cash Flow on a prospective basis. Prior periods are not adjusted. We also made the accounting policy election to account for forfeitures as they occur. Recently Issued Accounting Pronouncements In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers, which supersedes previous revenue recognition guidance. The new guidance introduces a new principles-based framework for revenue recognition and disclosure. Since its issuance, the FASB has issued an additional six ASUs, including ASU 2016-20 in December 2016, amending the guidance and the effective dates of amendments, and the SEC has rescinded certain related SEC guidance; the most recent of which was issued in May 2016. The pronouncements are effective for annual reporting periods beginning after December 15, 2017, including interim reporting periods within that reporting period. Earlier application is permitted only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period. We have not yet completed our final review of the impact of this guidance, although we currently do not anticipate a material impact on our revenue recognition practices. We continue to review our existing contracts with our customers, any variable consideration, potential disclosures, and our method of adoption to complete our evaluation of the impact on our consolidated financial statements. In addition, we continue to monitor additional changes, modifications, clarifications or interpretations being undertaken by the FASB, which may impact our current conclusions. In February 2016, the FASB issued ASU 2016-02, Leases, which supersedes the existing lease guidance and requires all leases with a term greater than 12 months to be recognized on the balance sheet as assets and obligations. This Update is effective for public entities for financial statements issued for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years; early application is permitted. This standard mandates a modified retrospective transition method. We have not yet determined the impact from adoption of this new accounting pronouncement on our financial statements. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments. The Update provides amendments that clarify guidance or correct references in the Accounting Standards Codification that addresses current diversity in practice and could potentially result in changes in current practice because of either misapplication or misunderstanding of current guidance. Early adoption is permitted for the amendments that require transition guidance. We are currently evaluating the effect that the transition guidance will have on our financial statements and related disclosures. In December 2016, the FASB issued ASU 2016-19, Technical Corrections and Improvements. Most of the amendments are effective upon issuance. Six amendments clarify guidance or correct references in the Accounting Standards Codification that could potentially result in changes in current practice because of either misapplication or misunderstanding of current guidance. The transition guidance effective dates for these six amendments varies depending upon the amendment, relevant Subtopic and applicability to other ASUs. Early adoption is permitted for the amendments that require transition guidance. We are currently evaluating the effect that the transition guidance will have on our financial statements and related disclosures.

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2016

Accounting Policies [Abstract]

Changes in Asset Retirement Obligation

The changes in these obligations (in thousands) during the year ending December 31, 2016 and 2015 are as follows:



	2016			2015
Beginning balance	$	12,254		$	11,283
Accretion	979			812
Additions and revisions of prior estimates	(2,074		)	159
Ending balance	$	11,159		$	12,254

Summary of Valuation Assumptions



	Weighted-average
	Year ended December 31,
		2015		2014
Risk-free interest rate		1.68	%	1.81	%
Expected volatility		48	%	45	%
Expected term		6.25 years		6.25 years
Expected dividend yield		1	%	1	%
Expected forfeiture rate		0	%	0	%

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share

The weighted-average stock options (in thousands) that are antidilutive and are therefore excluded from the calculation of diluted earnings per common share are:



	For the Year Ended December 31,
	2016	2015	2014
Weighted-average outstanding stock options excluded	573	528	33
Weighted-average outstanding restricted stock awards excluded	166	66	20

Capital Structure and Accumulated Comprehensive Income (Tables)

12 Months Ended

Dec. 31, 2016

Equity [Abstract]

Schedule of Declared Quarterly Dividends

In 2016, our Board of Directors declared quarterly cash dividends as follows:



Dividends per Common Share		Declaration Date	Record Date	Payable Date
$	0.0625	February 22, 2016	March 15, 2016	April 5, 2016
$	0.0625	May 5, 2016	June 15, 2016	July 6, 2016
$	0.0625	July 21, 2016	September 15, 2016	October 4, 2016
$	0.0625	November 3, 2016	December 15, 2016	January 5, 2017

Changes in Accumulated Other Comprehensive Income

The following table presents the changes in accumulated other comprehensive income by component (in thousands) during the year ended December 31, 2016:



	For the Year Ended December 31, 2016
	Unrealized gain (loss) on cash flow hedges			Unrealized gain (loss) on short-term investments			Pension and other post- retirement benefits liability			Total
Beginning Balance	$	(81	)	$	6		$	(16,096	)	$	(16,171	)
Other comprehensive income before reclassifications	(32		)	(6		)	(760		)	(798		)
Amounts reclassed from accumulated other comprehensive income	81			—			1,012			1,093
Ending Balance	$	(32	)	$	—		$	(15,844	)	$	(15,876	)

Business Combinations (Tables)

12 Months Ended

Dec. 31, 2016

Business Combinations [Abstract]

Schedule of Business Acquisitions, by Acquisition

The calculation of preliminary purchase price (in thousands, except shares) is as follows:




Cash consideration paid			$	70,760
Number of Holdings common shares delivered	4,195,180
Multiplied by closing market price per share of U.S. Silica common stock on August 22, 2016	$	40.92
Total value of Holdings common shares delivered			$	171,667
Less, cash acquired			$	(1,306	)
Total purchase price			$	241,121

The calculation of the preliminary purchase price (in thousands, except shares) is as follows:




Cash consideration paid			$	116,165
Number of Holdings common shares delivered	2,630,513
Multiplied by closing market price per share of U.S. Silica common stock on August 16, 2016	$	40.51
Total value of Holdings common shares delivered			$	106,562
Less, cash acquired			$	(9,002	)
Total purchase price			$	213,725

Schedule of Identifiable Assets Acquired and Liabilities Assumed

The following table sets forth the preliminary allocation of the purchase price to the identifiable tangible and intangible assets acquired and liabilities assumed (in thousands):



Allocation of Purchase price:
Accounts receivable	$	2,680
Inventories	3,494
Other current assets	428
Income tax deposits	6,657
Property, plant and mine development	210,913
Identifiable intangible assets	1,600
Goodwill	86,228
Total assets acquired	312,000
Accounts payable, accrued expenses and other current liabilities	1,938
Deferred revenue	500
Notes payable	24,361
Capital lease liabilities	3,331
Asset retirement obligations	710
Deferred tax liabilities	67,435
Total liabilities assumed	98,275
Net assets acquired	$	213,725

The following table sets forth a preliminary allocation of the purchase price to Sandbox’s identifiable tangible and intangible assets acquired and liabilities assumed (in thousands):



Allocation of Purchase price:	(in thousands)
Accounts receivable	$	13,392
Prepaid expenses and other	1,465
Property, plant and mine development	32,336
Identifiable intangible assets	120,144
Goodwill	86,100
Total assets acquired	253,437
Accounts payable	4,122
Deferred revenue	4,902
Accrued expenses and other current liabilities	3,292
Total liabilities assumed	12,316
Net assets acquired	$	241,121

Summary of Identifiable Intangible Assets

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	$	1,600	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)
Indefinite lived intangible assets - Trade names	$	17,844	Indefinite
Definite lived intangible assets - Technology and intellectual property	57,700		15
Definite lived intangible asset - Customer relationships	44,600		13
Total fair value of identifiable intangible assets	$	120,144

Pro Forma Summary

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,
	2016			2015
Sales	$	615,552		$	753,287
Net income (loss)	$	(45,161	)	$	43,163
Basic earnings per share	$	(0.69	)	$	0.81
Diluted earnings per share	$	(0.69	)	$	0.81

Accounts Receivable (Tables)

12 Months Ended

Dec. 31, 2016

Receivables [Abstract]

Schedule of Accounts Receivable

Changes in our allowance for doubtful accounts (in thousands) during the years ended December 31, 2016 and 2015 are as follows:



	Allowance for Doubtful Accounts
	2016			2015
Balance at January 1,	$	7,686		$	10,429
Bad debt provision	(1,232		)	(290		)
Write-offs and recoveries	588			(2,453		)
Balance at December 31,	$	7,042		$	7,686

At December 31, 2016 and 2015, accounts receivable (in thousands) consisted of the following:



	At December 31,
	2016			2015
Trade receivables	$	93,982		$	64,821
Less: Allowance for doubtful accounts	(7,042		)	(7,686		)
Net trade receivables	86,940			57,135
Other receivables	2,066			1,571
Total accounts receivable	$	89,006		$	58,706

Inventories (Tables)

12 Months Ended

Dec. 31, 2016

Inventory Disclosure [Abstract]

Schedule of Inventories

At December 31, 2016 and 2015, inventories (in thousands) consisted of the following:



	At December 31,
	2016		2015
Supplies	$	18,824	$	18,029
Raw materials and work in process	25,161		18,113
Finished goods	34,724		28,862
Total inventories	$	78,709	$	65,004

Property, Plant and Mine Development (Tables)

12 Months Ended

Dec. 31, 2016

Property, Plant and Equipment [Abstract]

Schedule of Property, Plant and Mine Development

At December 31, 2016 and 2015, property, plant and mine development (in thousands) consisted of the following:



	At December 31,
	2016			2015
Mining property and mine development	$	414,434		$	222,439
Asset retirement cost	8,062			9,889
Land	35,052			30,322
Land improvements	42,738			37,791
Buildings	52,178			51,280
Machinery and equipment	450,881			360,817
Furniture and fixtures	2,566			1,917
Construction-in-progress	43,790			56,130
	1,049,701			770,585
Accumulated depletion, depreciation and amortization	(266,388		)	(209,389		)
Total property, plant and mine development, net	$	783,313		$	561,196

Debt and Capital Leases (Tables)

12 Months Ended

Dec. 31, 2016

Debt Disclosure [Abstract]

Schedule of Debt

At December 31, 2016 and 2015, debt (in thousands) consisted of the following:



	December 31, 2016			December 31, 2015
Senior secured credit facility:
Revolver expiring July 23, 2018 (5.25% at December 31, 2016 and 5% at December 31, 2015)	$	—		$	—
Term loan facility—final maturity July 23, 2020 (4% - 4.5% at December 31, 2016 and December 31, 2015)	494,175			499,275
Less: Unamortized original issue discount	(1,318		)	(1,696		)
Less: Unamortized debt issuance cost	(4,482		)	(5,874		)
Note payable secured by royalty interest (includes $3,053 unamortized fair value premium)	23,076			—
Customer note payable	1,787			—
Total debt	513,238			491,705
Less: current portion	(4,821		)	(3,330		)
Total long-term portion of debt	$	508,417		$	488,375

Schedule of Contractual Maturities of Debt

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



2017	$	1,750
2018	1,750
2019	1,750
2020	1,750
2021	1,750

At December 31, 2016, contractual maturities of senior secured credit facility (in thousands) are as follows:



2017	$	5,100
2018	5,100
2019	5,100
2020	478,875
	$	494,175

Debt and Capital Leases Disclosures

At December 31, 2016, scheduled future minimum lease payments under capital lease obligations (in thousands) are as follows:



2017	$	2,315
2018	722
Total minimum lease payments	3,037
Less: amount representing interest	(83		)
Present value of minimum lease payments	2,954
Less: current portion of capital lease obligations	(2,237		)
Non-current portion of capital lease obligations	$	717

Fair Value Accounting (Tables)

12 Months Ended

Dec. 31, 2016

Fair Value Disclosures [Abstract]

Schedule of Measure at Fair Value on Recurring Basis



	December 31, 2016						December 31, 2015
	Level 1		Level 2		Total		Level 1		Level 2		Total
Short-term investments	$	—	$	—	$	—	$	1	$	21,848	$	21,849
Interest rate derivatives	—		72		72		—		—		—
Net asset	$	—	$	72	$	72	$	1	$	21,848	$	21,849

Short-Term Investments (Tables)

12 Months Ended

Dec. 31, 2016

Investments, Debt and Equity Securities [Abstract]

Summary of Available-for-sale Short-Term Investments

The following table summarizes our available-for-sale short-term investments (in thousands) as of December 31, 2015:



	Aggregate Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
December 31, 2015
Money market mutual funds	$	1	$	—	$	—		$	1
Fixed income securities:
Certificates of deposit	10,535		—		(3		)	10,532
Commercial paper	5,689		19		—			5,708
Corporate notes and bonds	2,006		—		—			2,006
Government agencies	3,598		4		—			3,602
U.S. Treasuries	—		—		—			—
Variable rate demand obligations	—		—		—			—
Total available-for-sale investments	$	21,829	$	23	$	(3	)	$	21,849

- Definition

Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities.

+ References + Details

Derivative Instruments (Tables)

12 Months Ended

Dec. 31, 2016

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Estimated Fair Values of Derivative Instruments



		December 31, 2016								December 31, 2015
	Maturity Date	Contract/Notional Amount			Carrying Amount		Fair Value		Maturity Date	Contract/Notional Amount			Carrying Amount		Fair Value
Interest rate cap agreement⁽¹⁾	2019	$	249	million	$	72	$	72	2016	$	252	million	$	—	$	—

⁽¹⁾Agreements limit the LIBOR floating interest rate base to 4%.

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



	2016			2015			2014
Deferred losses from derivatives in OCI, beginning of period	$	(81	)	$	(134	)	$	(79	)
Loss recognized in OCI from derivative instruments	(32		)	—			(65		)
Loss reclassified from Accumulated OCI	81			53			10
Deferred losses from derivatives in OCI, end of period	$	(32	)	$	(81	)	$	(134	)

Equity-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of Activity with Respect to Stock Options

The following table summarizes the status of and changes in our stock option grants during the year ended December 31, 2016:



	Number of Shares		Weighted Average Exercise Price	Aggregate Intrinsic Value (in thousands)		Weighted Average Remaining Contractual Term in Years
Outstanding at December 31, 2015	1,307,067		24.61
Granted	—		—
Exercised	(326,884	)	14.76
Forfeited	(27,490	)	24.81
Outstanding at December 31, 2016	952,693		27.99	$	27,332	7.00 years
Exercisable at December 31, 2016	597,799		23.71	$	19,712	6.33 years

Summary of Restricted Stock Award Activity

The following table summarizes the status of and changes in our performance share unit awards during the year ended December 31, 2016:



	Number of Shares		Grant Date Weighted Average Fair Value
Unvested, December 31, 2015	277,066		$	29.05
Granted	850,143		39.36
Vested	—		—
Forfeited	(163,596	)	33.30
Unvested, December 31, 2016	963,613		$	32.63

The following table summarizes the status of and changes in our unvested restricted stock awards during the year ended December 31, 2016:



	Number of Shares		Grant Date Weighted Average Fair Value
Unvested, December 31, 2015	398,987		$	26.65
Granted	364,710		22.97
Vested	(180,419	)	26.28
Forfeited	(25,562	)	27.26
Unvested, December 31, 2016	557,716		$	24.33

Pension and Post-Retirement Benefits (Tables)

12 Months Ended

Dec. 31, 2016

Compensation and Retirement Disclosure [Abstract]

Summarizes Information about Pension and Post-Retirement Benefit Plans

Net pension benefit cost (in thousands) consisted of the following for the years ended December 31, 2016, 2015 and 2014:



	Years Ended December 31,
	2016			2015			2014
Service cost—benefits earned during the period	$	1,078		$	1,295		$	1,080
Interest cost	4,067			4,813			4,811
Expected return on plan assets	(5,495		)	(5,498		)	(5,146		)
Net amortization and deferral	1,592			2,665			1,037
Net pension benefit costs	$	1,242		$	3,275		$	1,782

Net post-retirement cost (in thousands) consisted of the following for the years ended December 31, 2016, 2015 and 2014:



	Years Ended December 31,
	2016			2015			2014
Service cost—benefits earned during the period	$	132		$	176		$	151
Interest cost	876			1,074			1,030
Expected return on plan assets	(1		)	(1		)	(4		)
Net amortization and deferral	—			281			—
Special termination benefit	21			48			—
Net post-retirement costs	$	1,028		$	1,578		$	1,177

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, 2016 and 2015 are as follows:



	Pension Benefits						Post-retirement Benefits
	2016			2015			2016			2015
Benefit obligation at January 1,	$	115,420		$	122,336		$	25,091		$	28,289
Service cost	1,078			1,295			132			176
Interest cost	4,067			4,813			876			1,074
Actuarial (gain) loss	1,640			(7,492		)	(802		)	(3,631		)
Benefits paid	(6,517		)	(6,106		)	(1,332		)	(1,288		)
Amendments	457			574			—			—
Special termination benefits	—			—			21			48
Other	—			—			407			423
Benefit obligation at December 31,	$	116,145		$	115,420		$	24,393		$	25,091
Fair value of plan assets at January 1,	$	84,716		$	90,897		$	17		$	19
Actual return on plan assets	5,651			(2,100		)	(3		)	(2		)
Employer contributions	—			2,025			925			864
Benefits paid	(6,517		)	(6,106		)	(1,332		)	(1,288		)
Other	—			—			407			424
Fair value of plan assets at December 31,	$	83,850		$	84,716		$	14		$	17
Plan assets less than benefit obligations at December 31 recognized as liability for pension and other post-retirement benefits	$	(32,295	)	$	(30,704	)	$	(24,379	)	$	(25,074	)

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, 2016 are as follows:



	Benefits
			Post-retirement
	Pension		Before Medicare Subsidy		After Medicare Subsidy
2017	$	6,824	$	1,570	$	1,429
2018	7,050		1,544		1,402
2019	7,201		1,521		1,379
2020	7,343		1,598		1,452
2021	7,419		1,676		1,528
2022-2026	38,158		8,627		7,839

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

The amounts in accumulated other comprehensive income expected to be recognized as components of net periodic benefit cost (in thousands) during the year ended December 31, 2016 are as follows:



	Benefits
	Pension		Post-retirement		Total
Net actuarial loss	$	1,372	$	—	$	1,372
Prior service cost	411		—		411
	$	1,783	$	—	$	1,783

Company's Obligations Determined under Weighted-Average Assumptions

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



	Pension Benefits				Post-retirement Benefits
	2016		2015		2016		2015
Discount rate	4.2	%	4.5	%	4.2	%	4.5	%
Long-term rate of compensation increase	3.5	%	3.5	%	N/A		N/A
Long-term rate of return on plan assets	7.0	%	7.0	%	7.0	%	7.0	%
Health care cost trend rate:
Pre-65 initial rate/ultimate rate	N/A		N/A		7.3%/5.0%		7.8%/5.0%
Pre-65 ultimate year	N/A		N/A		—		—
Post-65 initial rate/ultimate rate	N/A		N/A		8.5%/5.0%		9.0%/5.0%
Post-65 ultimate year	N/A		N/A		2024/2025		2024/2025

Schedule of Mortality Tables Used

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



	Pension Benefits and Post-retirement Benefits
	2016	2015
Healthy lives	RP-2014 mortality table, adjusted back to 2006 base rates, with generational mortality improvements using Scale MP-2016	RP-2014 mortality table, adjusted back to 2006 base rates, with generational mortality improvements using Scale MP-2015
Disabled lives	RP-2014 disabled retiree mortality table, adjusted back to 2006 base rates, with generational mortality improvements using Scale MP-2016	RP-2014 disabled retiree mortality table, adjusted back to 2006 base rates, with generational mortality improvements using Scale MP-2015

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	$	144	$	(120	)
Effect on post-retirement benefit obligation	2,827		(2,406		)

Fair Value of Pension Plan Assets

The major investment categories and their relative percentage of the fair value of total plan assets as invested at December 31, 2016, and 2015 are as follows:



	Pension Benefits				Post-retirement Benefits
	2016		2015		2016		2015
Equity securities	59.4	%	58.1	%	64.0	%	52.5	%
Debt securities	38.3	%	40.0	%	39.1	%	35.3	%
Cash	2.3	%	1.9	%	(3.1	)%	12.2	%

Fair Value of Pension Plan Assets, by Asset Category

The fair values of the pension plan assets (in thousands) at December 31, 2016, by asset category, are as follows:



	Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	—	$	1,893	$	—	$	1,893
Mutual funds:
Diversified emerging markets	7,700		—		—		7,700
Foreign large blend	12,621		—		—		12,621
Large-cap blend	16,687		—		—		16,687
Mid-cap blend	8,674		—		—		8,674
Real estate	4,070		—		—		4,070
Fixed income securities:
Corporate notes and bonds	21,357		—		—		21,357
Government agencies	301		—		—		301
U.S. Treasuries	7,495		—		—		7,495
Mortgage-backed securities	—		2,022		—		2,022
Asset-backed securities	—		983		—		983
Insurance policies	—		—		47		47
Net asset	$	78,905	$	4,898	$	47	$	83,850

The fair values of the pension plan assets (in thousands) at December 31, 2015, by asset category, are as follows:



	Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	—	$	1,635	$	—	$	1,635
Mutual funds:
Diversified emerging markets	6,890		—		—		6,890
Foreign large blend	13,111		—		—		13,111
Large-cap blend	16,855		—		—		16,855
Mid-cap blend	7,769		—		—		7,769
Real estate	4,369		—		—		4,369
Fixed income securities:
Corporate notes and bonds	22,559		—		—		22,559
Government agencies	607		—		—		607
U.S. Treasuries	5,384		—		—		5,384
Mortgage-backed securities	—		3,111		—		3,111
Asset-backed securities	—		2,375		—		2,375
Insurance policies	—		—		51		51
Net asset	$	77,544	$	7,121	$	51	$	84,716

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

2016

2015

2016

2015

2014

LIUNA

52-6074345/001

Red

Yes

167

182

149

Yes

5/31/2017

IUOE

36-6052390/001

Green

7/29/2018

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.

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Summary of Income Tax (Expense) Benefit

The expense or benefit for income taxes (in thousands) consisted of the following for the years ended December 31, 2016, 2015 and 2014:



	Years Ended December 31,
	2016			2015			2014
Current:
Federal	$	60		$	(170	)	$	(34,790	)
State	(274		)	1,448			(4,835		)
	$	(214	)	$	1,278		$	(39,625	)
Deferred:
Federal	32,944			7,439			(308		)
State	3,959			3,034			2,750
	$	36,903		$	10,473		$	2,442
Income tax benefit (expense)	$	36,689		$	11,751		$	(37,183	)

Summary 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, 2016 and 2015 consisted of the following:



	At December 31,
	2016			2015
Gross deferred tax assets:
Net operating loss carry forward and state tax credits	$	65,022		$	39,280
Pension and post-retirement benefit costs	22,920			22,577
Alternative minimum tax credit carry forward	19,431			19,049
Property, plant and equipment	6,112			6,657
Accrued expenses	6,752			3,765
Inventories	4,362			6,425
Third-party products liability	511			568
Stock-based compensation expense	5,576			3,365
Note payable	4,009			—
Other	5,458			5,373
Total deferred tax assets	$	140,153		$	107,059
Gross deferred tax liabilities:
Land and mineral property basis difference	$	(126,315	)	$	(63,488	)
Fixed assets and depreciation	(61,531		)	(54,913		)
Intangibles	(2,260		)	(8,049		)
Other	(122		)	(122		)
Total deferred tax liabilities	$	(190,228	)	$	(126,572	)
Net deferred tax liabilities	$	(50,075	)	$	(19,513	)

Summary of Effective Income Tax Rate on Pretax Earnings



	Years Ended December 31,
	2016			2015			2014
Income tax benefit (expense) computed at U.S. federal statutory rate	$	27,211		$	(41	)	$	(55,553	)
Decrease (increase) resulting from:
Statutory depletion	4,734			8,918			15,548
Prior year tax return reconciliation	435			393			1,018
State income taxes, net of federal benefit	2,369			1,370			(3,416		)
Domestic production deduction	—			—			3,911
Equity compensation	2,003			—			—
Other, net	(63		)	1,111			1,309
Income tax benefit (expense)	$	36,689		$	11,751		$	(37,183	)

Segment Reporting (Tables)

12 Months Ended

Dec. 31, 2016

Segment Reporting [Abstract]

Presentation of Sales and Segment Contribution Margin for Reporting Segments and Other Operating Results



	Years Ended December 31,
	2016			2015			2014
Sales:
Oil & Gas Proppants	$	362,550		$	430,435		$	662,770
Industrial & Specialty Products	197,075			212,554			213,971
Total sales	$	559,625		$	642,989		$	876,741
Segment contribution margin:
Oil & Gas Proppants	$	11,445		$	88,928		$	256,137
Industrial & Specialty Products	78,988			70,137			61,102
Total segment contribution margin	$	90,433		$	159,065		$	317,239
Operating activities excluded from segment cost of goods sold	(8,103		)	(11,142		)	(7,082		)
Selling, general and administrative	(67,727		)	(62,777		)	(88,971		)
Depreciation, depletion and amortization	(68,134		)	(58,474		)	(45,019		)
Interest expense	(27,972		)	(27,283		)	(18,202		)
Other income, net, including interest income	3,758			728			758
Income tax benefit (expense)	$	36,689		11,751			(37,183		)
Net income (loss)	$	(41,056	)	$	11,868		$	121,540

Unaudited Supplementary Data (Tables)

12 Months Ended

Dec. 31, 2016

Quarterly Financial Information Disclosure [Abstract]

Unaudited Quarterly Information



	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
2016:	(Unaudited)
Sales	$	122,510		$	116,994		$	137,748		$	182,373
Cost of goods sold (excluding depreciation, depletion and amortization)	106,751			102,707			119,426			148,411
Operating expenses
Selling, general and administrative	15,503			14,585			18,472			19,167
Depreciation, depletion and amortization	14,556			15,209			17,175			21,194
	$	30,059		$	29,794		$	35,647		$	40,361
Operating loss	(14,300		)	(15,507		)	(17,325		)	(6,399		)
Other income (expense)
Interest expense	(6,643		)	(6,647		)	(6,684		)	(7,998		)
Other income, net, including interest income	1,790			608			493			867
	$	(4,853	)	$	(6,039	)	$	(6,191	)	$	(7,131	)
Loss before income taxes	(19,153		)	(21,546		)	(23,516		)	(13,530		)
Income tax benefit	8,150			9,774			12,177			6,588
Net loss	$	(11,003	)	$	(11,772	)	$	(11,339	)	$	(6,942	)
Loss per share, basic	$	(0.20	)	$	(0.19	)	$	(0.17	)	$	(0.09	)
Loss per share, diluted	$	(0.20	)	$	(0.19	)	$	(0.17	)	$	(0.09	)
Weighted average shares outstanding, basic	54,470			63,417			66,676			75,539
Weighted average shares outstanding, diluted	54,470			63,417			66,676			75,539
Dividends declared per share	$	0.06		$	0.06		$	0.06		$	0.06

	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
2015:	(Unaudited)
Sales	$	203,958		$	147,511		$	155,408		$	136,112
Cost of goods sold (excluding depreciation, depletion and amortization)	138,653			117,200			122,599			116,614
Operating expenses
Selling, general and administrative	26,961			6,575			13,559			15,682
Depreciation, depletion and amortization	13,243			13,695			15,158			16,378
	$	40,204		$	20,270		$	28,717		$	32,060
Operating income (loss)	25,101			10,041			4,092			(12,562		)
Other income (expense)
Interest expense	(6,836		)	(6,928		)	(6,684		)	(6,835		)
Other income (loss), net, including interest income	11			498			309			(90		)
	$	(6,825	)	$	(6,430	)	$	(6,375	)	$	(6,925	)
Income before income taxes	18,276			3,611			(2,283		)	(19,487		)
Income tax benefit (expense)	(3,453		)	6,342			4,695			4,167
Net income (loss)	$	14,823		$	9,953		$	2,412		$	(15,320	)
Earnings (loss) per share, basic	$	0.28		$	0.19		$	0.05		$	(0.29	)
Earnings (loss) per share, diluted	$	0.28		$	0.18		$	0.04		$	(0.29	)
Weighted average shares outstanding, basic	53,416			53,303			53,321			53,323
Weighted average shares outstanding, diluted	53,869			53,857			53,742			53,323
Dividends declared per share	$	0.13		$	0.13		$	0.13		$	0.06

Parent Company Financials (Tables)

12 Months Ended

Dec. 31, 2016

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Condensed Balance Sheet



	December 31,
	2016			2015
	(in thousands)
ASSETS
Current Assets:
Cash and cash equivalents	$	534,378		$	58,579
Short-term investments	—			21,849
Total current assets	534,378			80,428
Investment in subsidiaries	854,860			417,462
Total assets	$	1,389,238		$	497,890
LIABILITIES AND STOCKHOLDERS’ EQUITY
Current Liabilities:
Accrued expenses and other current liabilities	$	461		$	107
Dividends payable	5,222			3,453
Due to affiliates	110,265			110,159
Total current liabilities	115,948			113,719
Deferred income taxes, net	—			4
Total liabilities	115,948			113,723
Stockholders’ Equity:
Preferred stock	—			—
Common stock	811			539
Additional paid-in capital	1,129,051			194,670
Retained earnings	163,173			220,974
Treasury stock, at cost	(3,869		)	(15,845		)
Accumulated other comprehensive loss	(15,876		)	(16,171		)
Total stockholders’ equity	1,273,290			384,167
Total liabilities and stockholders’ equity	$	1,389,238		$	497,890

Condensed Income Statement



	Year Ended December 31,
	2016			2015			2014
	(in thousands, except per share amounts)
Revenue	$	—		$	—		$	—
Cost of revenue	—			—			—
Operating expenses
Selling, general and administrative	184			185			184
Other	10			19			—
	194			204			184
Operating loss	(194		)	(204		)	(184		)
Other income (expense)
Interest income	1,046			262			278
Early extinguishment of debt	—			—			—
Other income, net, including interest income	—			1			—
	1,046			263			278
Income before income taxes and equity in net earnings of subsidiaries	852			59			94
Income tax benefit (expense)	(344		)	(24		)	(38		)
Income before equity in net earnings of subsidiaries	508			35			56
Equity in earnings of subsidiaries, net of tax	(41,564		)	11,833			121,484
Net income (loss)	(41,056		)	11,868			121,540
Other comprehensive income (loss), net of deferred income taxes:
Unrealized gain (loss) on investments (net of tax of ($4), $29, and ($8) for 2016, 2015, and 2014, respectively)	(6		)	47			(14		)
Unrealized loss on derivatives, (net of tax of $29, $34 and ($32) for 2016, 2015 and 2014, respectively)	49			53			(55		)
Pension and post-retirement liability (net of tax of $152, $2,469, and ($9,678) for 2016, 2015 and 2014, respectively)	252			3,547			(15,732		)
Other comprehensive income (loss), net of deferred income taxes	295			3,647			(15,801		)
Comprehensive income (loss) attributable to U.S. Silica Holdings, Inc.	$	(40,761	)	$	15,515		$	105,739

Condensed Equity Statement



													Accumulated
						Additional				Retained			Other			Total
	Par		Treasury			Paid-In				Earnings-			Comprehensive			Stockholders'
	Value		Stock			Capital				Present			Income (Loss)			Equity
Balance at January 1, 2014	$	534	$	—		$	174,799			$	137,978		$	(4,017	)	$	309,294
Net income	—		—			—				121,540			—			121,540
Unrealized loss on derivatives	—		—			—				—			(55		)	(55		)
Unrealized loss on short-term investments	—		—			—			—	—			(14		)	(14		)
Pension and post-retirement liability	—		—			—				—			(15,732		)	(15,732		)
Cash dividend declared ($0.500 per share)	—		—			—				(26,967		)	—			(26,967		)
Common stock-based compensation plans activity:
Equity-based compensation	—		—			7,487				—			—			7,487
Excess tax benefit from equity compensation	—		—			3,813				—			—			3,813
Proceeds from options exercised	4		572			4,987				—			—			5,563
Shares withheld for employee taxes related to
vested restricted stock and stock units	1		(615		)	—				—			—			(614		)
Repurchase of common stock	—		(499		)	—				—			—			(499		)
Balance at December 31, 2014	539		(542		)	191,086				232,551			(19,818		)	403,816
Net income	—		—			—				11,868			—			11,868
Unrealized gain on derivatives	—		—			—				—			53			53
Unrealized gain on short-term investments	—		—			—				—			47			47
Pension and post-retirement liability	—		—			—				—			3,547			3,547
Cash dividend declared ($0.438 per share)	—		—			—				(23,445		)	—			(23,445		)
Common stock-based compensation plans activity:
Equity-based compensation	—		—			3,857				—			—			3,857
Proceeds from options exercised	—		744			(271		)		—			—			473
Shares withheld for employee taxes related to
vested restricted stock and stock units	—		(792		)	(2		)		—			—			(794		)
Repurchase of common stock	—		(15,255		)	—				—			—			(15,255		)
Balance at December 31, 2015	539		(15,845		)	194,670				220,974			(16,171		)	384,167
Net loss	—		—			—				(41,056		)	—			(41,056		)
Issuance of common stock (stock offerings net of issuance costs of $25,732)	272		—			931,016				—			—			931,288
Unrealized gain on derivatives	—		—			—				—			49			49
Unrealized loss on short-term investments	—		—			—				—			(6		)	(6		)
Pension and post-retirement liability	—		—			—				—			252			252
Cash dividend declared ($0.25 per share)	—		—			—				(16,893		)	—			(16,893		)
Common stock-based compensation plans activity:
Equity-based compensation	—		—			12,107				—			—			12,107
Excess tax benefit from equity-based compensation	—		—			—				148			—			148
Proceeds from options exercised	—		8,465			(3,640		)		—			—			4,825
Issuance of restricted stock	—		1,437			(1,437		)		—			—			—
Shares withheld for employee taxes related to
vested restricted stock and stock units	—		2,074			(3,665		)		—			—			(1,591		)
Balance at December 31, 2016	$	811	$	(3,869	)	$	1,129,051			$	163,173		$	(15,876	)	$	1,273,290

Condensed Cash Flow Statement



	Year Ended December 31,
	2016			2015			2014
	(in thousands)
Operating activities:
Net income (loss)	$	(41,056	)	$	11,868		$	121,540
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Undistributed (Income) loss from equity method investment, net	41,564			(11,833		)	(121,484		)
Other	(30		)	(195		)	(213		)
Changes in assets and liabilities, net of effects of acquisitions:
Accounts payable and accrued liabilities	353			29			36
Net cash provided by (used in) operating activities	831			(131		)	(121		)
Investing activities:
Proceeds from sales and maturities of short-term investments	21,872			53,568			—
Investment in subsidiary	(188,177		)	—			—
Net cash provided by (used in) investing activities	(166,305		)	53,568			—
Financing activities:
Dividends paid	(15,125		)	(26,797		)	(26,871		)
Repurchase of common stock	—			(15,255		)	(499		)
Proceeds from options exercised	4,603			473			5,563
Tax payments related to shares withheld for vested restricted stock and stock units	(1,590		)	(794		)	(614		)
Issuance of common stock (secondary offering)	678,791			—			—
Issuance of treasury stock	221			—			—
Costs of common stock issuance	(25,733		)	—			—
Net financing activities with subsidiaries	106			223			211
Net cash provided by (used in) financing activities	641,273			(42,150		)	(22,210		)
Net increase in cash and cash equivalents	475,799			11,287			(22,331		)
Cash and cash equivalents, beginning of period	58,579			47,292			69,623
Cash and cash equivalents, end of period	$	534,378		$	58,579		$	47,292
Non-cash financing activities:
Supplemental cash flow information:
Cash paid (received) during the period for:
Interest	$	(1,046	)	$	(263	)	$	(278	)
Non-cash transactions
Common stock issued for business acquisitions	$	278,229		$	—		$	—

Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016 USD ($) Agreement $ / shares	Dec. 31, 2015 USD ($) $ / shares	Dec. 31, 2014 USD ($)
Organization And Significant Accounting Policies
Weighted average fair value, grants during period (in dollars per share) \| $ / shares	$ 13.11	$ 19.37
Number of customers in the oil & gas proppants segment \| Agreement	7
Book overdrafts	$ 3,200,000	$ 6,700,000	$ 4,200,000
Additions and revisions of prior estimates	$ (2,074,000)	159,000
Percentage of fair value of reporting unit less than carrying amount	50.00%
Amortization in interest expense	$ 1,392,000	1,401,000	912,000
Self insurance reserve	5,300,000	5,700,000
Self-insurance reserve current	$ 1,300,000	1,800,000
Buildings
Organization And Significant Accounting Policies
Depreciation over the assets estimated useful life	15 years
Land improvements
Organization And Significant Accounting Policies
Depreciation over the assets estimated useful life	10 years
Furniture and fixtures
Organization And Significant Accounting Policies
Depreciation over the assets estimated useful life	8 years
Customer Relationships
Organization And Significant Accounting Policies
Weighted average amortization useful life	15 years
Remaining useful life	13 years
Gross carrying amount of intangible asset	$ 55,700,000
Amortization of Intangible Assets	1,800,000	$ 500,000	$ 400,000
Accumulated amortization	4,800,000
Estimated annual amortization, 2017	4,000,000
Estimated annual amortization, 2018	4,000,000
Estimated annual amortization, 2019	4,000,000
Estimated annual amortization, 2020	4,000,000
Estimated annual amortization, 2021	$ 4,000,000
Intellectual Property
Organization And Significant Accounting Policies
Weighted average amortization useful life	15 years
Remaining useful life	14 years 7 months 8 days
Gross carrying amount of intangible asset	$ 58,700,000
Amortization of Intangible Assets	1,400,000
Accumulated amortization	1,400,000
Estimated annual amortization, 2017	3,800,000
Estimated annual amortization, 2018	3,800,000
Estimated annual amortization, 2019	3,800,000
Estimated annual amortization, 2020	3,800,000
Estimated annual amortization, 2021	3,800,000
Intellectual Property, Capitalized Legal and Patent Filing Costs
Organization And Significant Accounting Policies
Gross carrying amount of intangible asset	900,000
Minimum
Organization And Significant Accounting Policies
Self-insured retentions	$ 100,000
Minimum \| Machinery and equipment
Organization And Significant Accounting Policies
Depreciation over the assets estimated useful life	3 years
Minimum \| Customer Relationships
Organization And Significant Accounting Policies
Weighted average amortization useful life	13 years
Maximum
Organization And Significant Accounting Policies
Self-insured retentions	$ 500,000
Maximum \| Machinery and equipment
Organization And Significant Accounting Policies
Depreciation over the assets estimated useful life	10 years
Maximum \| Customer Relationships
Organization And Significant Accounting Policies
Weighted average amortization useful life	20 years
Ten Largest Customers \| Product concentration risk \| Sales Revenue, Net
Organization And Significant Accounting Policies
Percentage of sales in which customers accounted	52.00%	56.00%	57.00%
Halliburton Company \| Product concentration risk \| Sales Revenue, Net
Organization And Significant Accounting Policies
Percentage of sales in which customers accounted	13.00%

Summary of Significant Accounting Policies - Change in Asset Retirement Obligation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Asset Retirement Obligation
Beginning balance	$ 12,254	$ 11,283
Accretion	979	812
Additions and revisions of prior estimates	(2,074)	159
Ending balance	$ 11,159	$ 12,254

Summary of Significant Accounting Policies - Equity-Based Compensation (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value, grants during period (in dollars per share)	$ 13.11	$ 19.37
Granted (in shares)	0
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Risk-free interest rate		1.68%	1.81%
Expected volatility		48.00%	45.00%
Expected term		6 years 3 months	6 years 3 months
Expected dividend yield		1.00%	1.00%
Expected forfeiture rate		0.00%	0.00%
Restricted stock and restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock vesting period	3 years
Minimum \| Stock option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock vesting period	3 years
Maximum \| Stock option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock vesting period	4 years

Summary of Significant Accounting Policies - Weighted-average Outstanding Stock Options Excluded Schedule (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average outstanding stock options excluded (in shares)	573	528	33
Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average outstanding stock options excluded (in shares)	166	66	20

Summary of Significant Accounting Policies - Recently Adopted Accounting Pronouncements (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
New Accounting Pronouncement, Early Adoption [Line Items]
Deferred income taxes, net	$ 50,075				$ 19,513				$ 50,075	$ 19,513
Reduction in provision for income taxes									2,200
Income tax benefit (expense)	(6,588)	$ (12,177)	$ (9,774)	$ (8,150)	(4,167)	$ (4,695)	$ (6,342)	$ 3,453	(36,689)	(11,751)	$ 37,183
New Accounting Pronouncement, Early Adoption, Effect \| Accounting Standards Update 2016-09
New Accounting Pronouncement, Early Adoption [Line Items]
Deferred income taxes, net	$ (2,200)				(100)				$ (2,200)	(100)
Income tax benefit (expense)			$ (200)	$ 300
Retained Earnings \| New Accounting Pronouncement, Early Adoption, Effect \| Accounting Standards Update 2016-09
New Accounting Pronouncement, Early Adoption [Line Items]
Effect of new accounting pronouncement in period of adoption					$ 100					$ 100

Capital Structure and Accumulated Comprehensive Income - Additional Information (Detail) - USD ($)					1 Months Ended			3 Months Ended								12 Months Ended
	Nov. 03, 2016	Jul. 21, 2016	May 05, 2016	Feb. 22, 2016	Nov. 30, 2016	Aug. 31, 2016	Mar. 31, 2016	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Common stock authorized (in shares)								500,000,000								500,000,000
Common stock, par value (in dollars per share)								$ 0.01								$ 0.01
Secondary offering (in shares)							10,000,000				10,000,000
Public offering, proceeds from issuance of common stock					$ 467,000,000		$ 186,200,000									$ 931,288,000
Common stock issued (in shares)								81,028,898				53,390,136				81,028,898	53,390,136
Common stock, shares outstanding (in shares)								81,028,898				53,390,136				81,028,898	53,390,136
Dividend declared per share (in usd per share)	$ 0.0625	$ 0.0625	$ 0.0625	$ 0.0625				$ 0.0625	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.125	$ 0.125	$ 0.125	$ 0.25	$ 0.438	$ 0.50
Declaration Date	Nov. 03, 2016	Jul. 21, 2016	May 05, 2016	Feb. 22, 2016
Record Date	Dec. 15, 2016	Sep. 15, 2016	Jun. 15, 2016	Mar. 15, 2016
Payable Date	Jan. 05, 2017	Oct. 04, 2016	Jul. 06, 2016	Apr. 05, 2016
Preferred stock, shares authorized (in shares)								10,000,000								10,000,000
Preferred stock, par value (in dollars per share)								$ 0.01								$ 0.01
Preferred stock issued (in shares)								0				0				0	0
Preferred stock, shares outstanding (in shares)								0				0				0	0
Authorization to repurchase common stock								$ 50,000,000								$ 50,000,000
Repurchase of common stock (shares)																706,093
Average price per common share of repurchase common stock (in dollars per share)																$ 23.83
Remaining authorized repurchase of common stock amount								$ 33,200,000								$ 33,200,000
Common Stock
Class of Stock [Line Items]
Additional offering, shares issued (in shares)						6,825,693										6,825,693
Common Stock
Class of Stock [Line Items]
Public offering, proceeds from issuance of common stock																$ 272,000
Additional offering, shares issued (in shares)					10,350,000

Capital Structure and Accumulated Comprehensive Income - Changes in Accumulated Other Comprehensive Income (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 384,167
Ending balance	1,273,290
Unrealized gain (loss) on cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(81)
Other comprehensive income before reclassifications	(32)
Amounts reclassed from accumulated other comprehensive income	81
Ending balance	(32)
Unrealized gain (loss) on short-term investments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	6
Other comprehensive income before reclassifications	(6)
Amounts reclassed from accumulated other comprehensive income	0
Ending balance	0
Pension and other post- retirement benefits liability
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(16,096)
Other comprehensive income before reclassifications	(760)
Amounts reclassed from accumulated other comprehensive income	1,012
Ending balance	(15,844)
Accumulated Other Comprehensive (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(16,171)
Other comprehensive income before reclassifications	(798)
Amounts reclassed from accumulated other comprehensive income	1,093
Ending balance	$ (15,876)

Business Combinations - Additional Information (Detail) $ in Thousands			1 Months Ended	3 Months Ended	12 Months Ended
	Aug. 22, 2016 USD ($) shares	Aug. 16, 2016 USD ($) shares	Aug. 31, 2016 shares	Mar. 31, 2013 USD ($)	Dec. 31, 2016 USD ($) acquisition shares	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Business Acquisition [Line Items]
Payments to acquire businesses, net of cash acquired					$ 176,617	$ 0	$ 98,317
Number of acquisitions \| acquisition					2
Payments of Stock Issuance Costs				$ 0	$ 25,732	$ 0
New Birmingham, Inc
Business Acquisition [Line Items]
Cash acquired		$ 9,002
Payments to acquire businesses, net of cash acquired		$ 107,200
Number of U.S. Silica common shares delivered \| shares		2,630,513
Acquisition related costs					1,400
Inventory write-down					1,700
Cash payments to acquire business		$ 116,165
Sandbox Enterprises LLC
Business Acquisition [Line Items]
Cash acquired	$ 1,306
Payments to acquire businesses, net of cash acquired	$ 69,500
Number of U.S. Silica common shares delivered \| shares	4,195,180
Acquisition related costs					3,000
Revenue					$ 31,000
Cash payments to acquire business	$ 70,760
Common Stock
Business Acquisition [Line Items]
Shares issued to complete acquisitions (in shares) \| shares			6,825,693		6,825,693
Payments of Stock Issuance Costs					$ 300

Business Combination - Schedule of Purchase Price Calculation (Details) - USD ($) $ / shares in Units, $ in Thousands	Aug. 22, 2016	Aug. 16, 2016
Business Acquisition [Line Items]
Multiplied by closing market price per share of U.S. Silica common stock on August 16, 2016	$ 40.92	$ 40.51
Sandbox Enterprises LLC
Business Acquisition [Line Items]
Cash consideration paid	$ 70,760
Number of Holdings common shares delivered	4,195,180
Total value of Holdings common shares delivered	$ 171,667
Less, cash acquired	(1,306)
Total purchase price	$ 241,121
New Birmingham, Inc
Business Acquisition [Line Items]
Cash consideration paid		$ 116,165
Number of Holdings common shares delivered		2,630,513
Total value of Holdings common shares delivered		$ 106,562
Less, cash acquired		(9,002)
Total purchase price		$ 213,725

Business Combination - Schedule of Purchase Price Allocation (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Aug. 22, 2016	Aug. 16, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Goodwill	$ 240,975			$ 68,647
Sandbox Enterprises LLC
Business Acquisition [Line Items]
Accounts receivable		$ 13,392
Prepaid expenses and other		1,465
Property, plant and mine development		32,336
Identifiable intangible assets		120,144
Goodwill		86,100
Total assets acquired		253,437
Accounts payable		4,122
Deferred revenue		4,902
Accrued expenses and other current liabilities		3,292
Total liabilities assumed		12,316
Net assets acquired		$ 241,121
New Birmingham, Inc
Business Acquisition [Line Items]
Accounts receivable			$ 2,680
Inventories			3,494
Other current assets			428
Income tax deposits			6,657
Property, plant and mine development			210,913
Identifiable intangible assets			1,600
Goodwill			86,228
Total assets acquired			312,000
Accounts payable, accrued expenses and other current liabilities			1,938
Deferred revenue			500
Notes payable			24,361
Capital lease liabilities			3,331
Asset retirement obligations			710
Deferred tax liabilities			67,435
Total liabilities assumed			98,275
Net assets acquired			$ 213,725

Business Combination - Schedule of Intangible Assets Acquired as Part of Business Combination (Details) - USD ($) $ in Thousands			12 Months Ended
	Aug. 22, 2016	Aug. 16, 2016	Dec. 31, 2016
Sandbox Enterprises LLC
Business Acquisition [Line Items]
Definite lived intangible assets - approximate fair value	$ 120,144
New Birmingham, Inc
Business Acquisition [Line Items]
Finite-lived intangible asset, useful life		15 years
Customer Relationships
Business Acquisition [Line Items]
Finite-lived intangible asset, useful life			15 years
Customer Relationships \| Sandbox Enterprises LLC
Business Acquisition [Line Items]
Definite lived intangible assets - approximate fair value	$ 44,600
Finite-lived intangible asset, useful life	13 years
Customer Relationships \| New Birmingham, Inc
Business Acquisition [Line Items]
Definite lived intangible assets - approximate fair value		$ 1,600
Developed Technology Rights \| Sandbox Enterprises LLC
Business Acquisition [Line Items]
Definite lived intangible assets - approximate fair value	$ 57,700
Finite-lived intangible asset, useful life	15 years
Trade Names \| Sandbox Enterprises LLC
Business Acquisition [Line Items]
Indefinite lived intangible assets - Trade names	$ 17,844

Business Combinations - Pro Forma Information (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Business Combinations [Abstract]
Sales	$ 615,552	$ 753,287
Net income	$ (45,161)	$ 43,163
Basic earnings per share (in dollars per share)	$ (0.69)	$ 0.81
Diluted earnings per share (in dollars per share)	$ (0.69)	$ 0.81

Accounts Receivable - Schedule of Accounts Receivable (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Receivables [Abstract]
Trade receivables	$ 93,982	$ 64,821
Less: Allowance for doubtful accounts	(7,042)	(7,686)
Net trade receivables	86,940	57,135
Other receivables	2,066	1,571
Total accounts receivable	$ 89,006	$ 58,706

Inventories - Schedule of Inventories (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Inventory Disclosure [Abstract]
Supplies	$ 18,824	$ 18,029
Raw materials and work in process	25,161	18,113
Finished goods	34,724	28,862
Total inventories	$ 78,709	$ 65,004

Accounts Receivable - Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at January 1,	$ 7,686	$ 10,429
Bad debt provision	(1,232)	(290)	$ 10,200
Write-offs and recoveries	588	(2,453)
Balance at December 31,	$ 7,042	$ 7,686	$ 10,429

Property, Plant and Mine Development - Schedule of Property, Plant and Mine Development (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment
Property, plant and mine development	$ 1,049,701	$ 770,585
Accumulated depletion, depreciation and amortization	(266,388)	(209,389)
Total property, plant and mine development, net	783,313	561,196
Mining property and mine development
Property, Plant and Equipment
Property, plant and mine development	414,434	222,439
Asset retirement cost
Property, Plant and Equipment
Property, plant and mine development	8,062	9,889
Land
Property, Plant and Equipment
Property, plant and mine development	35,052	30,322
Land improvements
Property, Plant and Equipment
Property, plant and mine development	42,738	37,791
Buildings
Property, Plant and Equipment
Property, plant and mine development	52,178	51,280
Machinery and equipment
Property, Plant and Equipment
Property, plant and mine development	450,881	360,817
Furniture and fixtures
Property, Plant and Equipment
Property, plant and mine development	2,566	1,917
Construction-in-progress
Property, Plant and Equipment
Property, plant and mine development	$ 43,790	$ 56,130

Property, Plant and Mine Development - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment
Machinery and equipment acquired under capital lease	$ 1,049,701,000	$ 770,585,000
Accumulated depletion, depreciation and amortization	266,388,000	209,389,000
Impairment of long-lived assets to be disposed of		1,100,000
Property plant equipment interest capitalization	200,000	500,000	$ 1,400,000
Assets Held under Capital Leases
Property, Plant and Equipment
Machinery and equipment acquired under capital lease	4,700,000	$ 0
Accumulated depletion, depreciation and amortization	$ 300,000

Accrued Liabilities - Schedule of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Payables and Accruals [Abstract]
Accrued salaries and wages	$ 3,794	$ 1,309
Accrued vacation liability	2,471	2,593
Current portion of liability for pension and post-retirement benefits	1,553	1,505
Accrued healthcare liability	1,307	1,830
Accrued property taxes and sales taxes	1,815	1,940
Other accrued liabilities	2,094	2,531
Total accrued liabilities	$ 13,034	$ 11,708

Debt and Capital Leases - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016 USD ($)	Aug. 16, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 05, 2014 USD ($)	Jul. 23, 2013 USD ($)
Short-term Debt
Available borrowing base					$ 425,000,000
Incurrence ratio	3
Facility consolidated total net leverage ratio	3.75
Increase of commitment	25.00%
Long-term debt	$ 513,238,000		$ 491,705,000
Revolving Credit Facility
Short-term Debt
Available borrowing base	50,000,000				50,000,000
Long-term line of credit	0
Remaining borrowing capacity under Revolver	46,000,000
Long-term debt	0		0
Swingline loans
Short-term Debt
Available borrowing base					5,000,000
Letter of Credit
Short-term Debt
Available borrowing base					20,000,000
Letters of credit outstanding, amount	4,000,000
Term loan facility
Short-term Debt
Available borrowing base				$ 502,000,000	$ 375,000,000.0
Increase in borrowing capacity				$ 135,000,000
Notes Payable, Other Payables \| Note Payable Secured by Royalty Interest
Short-term Debt
Annual minimum payments	500,000
Debt instrument, fair value	$ 22,500,000
Fair value inputs, discount rate	14.00%
Outstanding principal	$ 23,100,000.0
Long-term debt	23,076,000		0
Notes Payable, Other Payables \| Customer Note Payable
Short-term Debt
Annual minimum payments	500,000
Outstanding principal	$ 2,500,000.0
Debt instrument, stated interest rate percentage	0.00%
Consumer notes payable, term	60 months
Interest rate, effective percentage	3.50%
Long-term debt	$ 1,787,000	$ 1,900,000	$ 0
Payment in Kind (PIK) Interest \| Note Payable Secured by Royalty Interest
Short-term Debt
Increase in notes payable	$ 600,000

Debt and Capital Leases - Schedule of Debt (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Aug. 16, 2016	Dec. 31, 2015
Line of Credit Facility
Total debt	$ 513,238		$ 491,705
Less: Unamortized original issue discount	(1,318)		(1,696)
Less: Unamortized debt issuance cost	(4,482)		(5,874)
Less: current portion	(4,821)		(3,330)
Total long-term portion of debt	508,417		488,375
Revolving Credit Facility
Line of Credit Facility
Total debt	0		0
Senior Secured Credit Facility \| Term loan facility
Line of Credit Facility
Total debt	494,175		499,275
Notes Payable, Other Payables \| Note Payable Secured by Royalty Interest
Line of Credit Facility
Total debt	23,076		0
Notes Payable, Other Payables \| Customer Note Payable
Line of Credit Facility
Total debt	$ 1,787	$ 1,900	$ 0

Debt and Capital Leases - Schedule of Debt (Phantom) (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Senior Secured Credit Facility \| Revolver
Line of Credit Facility
Credit facility, interest rate	5.25%	5.00%
Senior Secured Credit Facility \| Minimum \| Term loan facility
Line of Credit Facility
Credit facility, interest rate	4.00%	4.00%
Senior Secured Credit Facility \| Maximum \| Term loan facility
Line of Credit Facility
Credit facility, interest rate	4.50%	4.50%
Notes Payable, Other Payables \| Note Payable Secured by Royalty Interest
Line of Credit Facility
Unamortized premium	$ 3,053

Debt and Capital Leases - Schedule of Contractual Maturities of Debt (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Total debt	$ 513,238	$ 491,705
Term loan facility \| Senior Secured Credit Facility
Debt Instrument [Line Items]
2017	5,100
2018	5,100
2019	5,100
2020	478,875
Total debt	$ 494,175	$ 499,275

Debt and Capital Leases - Schedule of Debt Backed by Secured Royalty Interest (Details) - Notes Payable, Other Payables - Note Payable Secured by Royalty Interest $ in Thousands	Dec. 31, 2016 USD ($)
Debt Instrument [Line Items]
2017	$ 1,750
2018	1,750
2019	1,750
2020	1,750
2021	$ 1,750

Debt and Capital Leases - Schedule of Capital Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Debt Disclosure [Abstract]
2017	$ 2,315
2018	722
Total minimum lease payments	3,037
Less: amount representing interest	83
Present value of minimum lease payments	2,954
Current portion of capital leases	2,237	$ 0
Obligations under capital lease	$ 717	$ 0

Deferred Revenue (Detail) - Supply Agreement $ in Millions	Jul. 03, 2014 USD ($)
Deferred Revenue Arrangement [Line Items]
Advances received from a customer	$ 100.0
Deferred revenue, interest rate on unused customer deposits	0.049

Fair Value Accounting - Schedule of Measure at Fair Value on Recurring Basis (Detail) - Measured at Fair Value on Recurring Basis - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Pension Plans, Postretirement and Other Employee Benefits
Short-term investments	$ 0	$ 21,849
Interest rate derivatives	72	0
Net asset	72	21,849
Level 1
Pension Plans, Postretirement and Other Employee Benefits
Short-term investments	0	1
Interest rate derivatives	0	0
Net asset	0	1
Level 2
Pension Plans, Postretirement and Other Employee Benefits
Short-term investments	0	21,848
Interest rate derivatives	72	0
Net asset	$ 72	$ 21,848

- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(12))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Trading Securities
-URI http://asc.fasb.org/extlink&oid=6526789

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(5))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 35
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=27723805&loc=d3e24584-111560

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=65884222&loc=d3e22054-111558

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(1))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Available-for-Sale Securities
-URI http://asc.fasb.org/extlink&oid=6505594

+ Details

Short-Term Investments - Schedule of Available-for-Sale Short-Term Investments (Detail) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities
Aggregate Cost		$ 21,829,000
Gross Unrealized Gains		23,000
Gross Unrealized Losses		(3,000)
Fair Value	$ 0	21,849,000
Money market mutual funds
Schedule of Available-for-sale Securities
Aggregate Cost		1,000
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Fair Value		1,000
Certificates of deposit
Schedule of Available-for-sale Securities
Aggregate Cost		10,535,000
Gross Unrealized Gains		0
Gross Unrealized Losses		(3,000)
Fair Value		10,532,000
Commercial paper
Schedule of Available-for-sale Securities
Aggregate Cost		5,689,000
Gross Unrealized Gains		19,000
Gross Unrealized Losses		0
Fair Value		5,708,000
Corporate notes and bonds
Schedule of Available-for-sale Securities
Aggregate Cost		2,006,000
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Fair Value		2,006,000
Government agencies
Schedule of Available-for-sale Securities
Aggregate Cost		3,598,000
Gross Unrealized Gains		4,000
Gross Unrealized Losses		0
Fair Value		3,602,000
U.S. Treasuries
Schedule of Available-for-sale Securities
Aggregate Cost		0
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Fair Value		0
Variable rate demand obligations
Schedule of Available-for-sale Securities
Aggregate Cost		0
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Fair Value		$ 0

Derivative Instruments - Estimated Fair Values of Derivative Instruments (Detail) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Interest Rate Cap Agreement
Derivative Instruments, Gain (Loss)
Contract/Notional Amount	$ 249,000,000	$ 252,000,000
Carrying Amount	$ 72,000	0
Maximum
Derivative Instruments, Gain (Loss)
Derivative, basis spread on variable rate	4.00%
Fair Value, Measurements, Recurring
Derivative Instruments, Gain (Loss)
Fair Value	$ 72,000	0
Fair Value, Inputs, Level 2 \| Fair Value, Measurements, Recurring
Derivative Instruments, Gain (Loss)
Fair Value	72,000	0
Fair Value, Inputs, Level 2 \| Fair Value, Measurements, Recurring \| Interest Rate Cap Agreement
Derivative Instruments, Gain (Loss)
Fair Value	$ 72,000	$ 0

Derivative Instruments - Effect of Derivatives Instruments on Combined Statements of Operations and Comprehensive Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred Losses from Derivatives in OCI [Roll Forward]
Deferred losses from derivatives in OCI, beginning of period	$ (81)	$ (134)	$ (79)
Loss recognized in OCI from derivative instruments	(32)	0	(65)
Loss reclassified from Accumulated OCI	81	53	10
Deferred losses from derivatives in OCI, end of period	$ (32)	$ (81)	$ (134)

Equity-Based Compensation - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Option Indexed to Issuer's Equity
Intrinsic value of stock options exercised	$ 7.6	$ 0.4	$ 10.9
Cash received from options exercised	4.8
Actual tax benefit realized for the tax deductions from option exercises	2.9	0.0	4.2
Stock option
Option Indexed to Issuer's Equity
Recognized compensation expense (benefit)	3.0	3.4	1.9
Unrecognized compensation expense related to stock options	$ 3.7
Recognized weighted-average period	1 year 6 months
Restricted Stock and Restricted Stock Units
Option Indexed to Issuer's Equity
Recognized compensation expense (benefit)	$ 5.7	3.9	2.2
Total unrecognized compensation expense	$ 9.5
Recognized weighted-average period	1 year 9 months 18 days
Performance Shares
Option Indexed to Issuer's Equity
Recognized compensation expense (benefit)	$ 3.3	$ (3.4)	$ 3.4
Total unrecognized compensation expense	$ 17.6
Recognized weighted-average period	1 year 8 months 12 days
2011 Incentive Compensation Plan
Option Indexed to Issuer's Equity
Issuable shares remaining under plan (in shares)	4,437,767

Equity-Based Compensation - Summary of Activity with Respect to Stock Options (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) $ / shares shares
Number of Shares
Outstanding at beginning of period (in shares) \| shares	1,307,067
Granted (in shares) \| shares	0
Exercised (in shares) \| shares	(326,884)
Forfeited (in shares) \| shares	(27,490)
Outstanding at period end (in shares) \| shares	952,693.000
Exercisable at period end (in shares) \| shares	597,799,000
Weighted Average Exercise Price
Outstanding at beginning of period, weighted average exercise price (in dollars per share) \| $ / shares	$ 24.61
Granted, weighted average exercise price (in dollars per share) \| $ / shares	0.00
Exercised, weighted average exercise price (in dollars per share) \| $ / shares	14.76
Forfeited, weighted average exercise price (in dollars per share) \| $ / shares	24.81
Outstanding at period end, weighted average exercise price (in dollars per share) \| $ / shares	27.99
Exercisable at period end, weighted average exercise price (in dollars per share) \| $ / shares	$ 23.71
Weighted Average Remaining Contractual Term in Years
Outstanding at period end, weighted average remaining contractual term in years	7 years
Exercisable at period end, weighted average remaining contractual term in years	6 years 4 months
Aggregate Intrinsic Value (in thousands)
Intrinsic value options outstanding \| $	$ 27,332
Intrinsic value options exercisable \| $	$ 19,712

Equity-Based Compensation - Restricted Stock Activity (Details) - Restricted Stock	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Number of Shares
Unvested at beginning of period (in shares) \| shares	398,987
Granted (in shares) \| shares	364,710
Vested (in shares) \| shares	(180,419)
Forfeited (in shares) \| shares	(25,562)
Unvested at period end (in shares) \| shares	557,716
Grant Date Weighted Average Fair Value
Unvested at beginning of period (in dollars per share) \| $ / shares	$ 26.65
Granted (in dollars per share) \| $ / shares	22.97
Vested (in dollars per share) \| $ / shares	26.28
Forfeited (in dollars per share) \| $ / shares	27.26
Unvested at period end (in dollars per share) \| $ / shares	$ 24.33

Equity-Based Compensation - Performance Stock Activity (Details) - Performance Shares	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Number of Shares
Unvested at beginning of period (in shares) \| shares	277,066
Granted (in shares) \| shares	850,143
Vested (in shares) \| shares	0
Forfeited (in shares) \| shares	(163,596)
Unvested at period end (in shares) \| shares	963,613
Weighted Average
Unvested at beginning of period (in dollars per share) \| $ / shares	$ 29.05
Granted (in dollars per share) \| $ / shares	39.36
Vested (in dollars per share) \| $ / shares	0.00
Forfeited (in dollars per share) \| $ / shares	33.30
Unvested at period end (in dollars per share) \| $ / shares	$ 32.63

Commitments and Contingencies - Contractual Obligations (Details) $ in Thousands	Dec. 31, 2016 USD ($)
Operating Lease Minimum Rental Payments
2017	$ 55,525
2018	63,221
2019	56,171
2020	48,774
2021	42,824
Thereafter	114,905
Total future lease and purchase commitments	381,420
Minimum Purchase Commitments
2017	20,739
2018	19,332
2019	17,590
2020	9,175
2021	3,450
Thereafter	12,800
Total future lease and purchase commitments	$ 83,086

Commitments and Contingencies - Additional Information (Detail) $ in Thousands		12 Months Ended
	Jun. 09, 2015 USD ($)	Dec. 31, 2016 USD ($) claim	Dec. 31, 2015 USD ($) claim	Dec. 31, 2014 USD ($) claim
Insurance [Abstract]
Expense related to operating leases and rental agreements		$ 54,100	$ 48,200	$ 33,300
Current portion of capital leases		$ 2,237	$ 0
New claims filed \| claim		2	0	1
Products liability claims outstanding \| claim		74
Third-party products claims liability under insurance in other assets		$ 300	$ 300
Third-party products claims liability under insurance in other long-term obligations		$ 1,300	$ 1,500
Selling, General and Administrative Expenses
Payments for legal settlements	$ 6,500

Pension and Post-Retirement Benefits - Summarizes Information about Pension and Post-Retirement Benefit Plans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Benefits
Pension Plans, Postretirement and Other Employee Benefits
Service cost—benefits earned during the period	$ 1,078	$ 1,295	$ 1,080
Interest cost	4,067	4,813	4,811
Expected return on plan assets	(5,495)	(5,498)	(5,146)
Net amortization and deferral	1,592	2,665	1,037
Net pension benefit or post-retirement costs	1,242	3,275	1,782
Post-retirement Benefits
Pension Plans, Postretirement and Other Employee Benefits
Service cost—benefits earned during the period	132	176	151
Interest cost	876	1,074	1,030
Expected return on plan assets	(1)	(1)	(4)
Net amortization and deferral	0	281	0
Special termination benefit	21	48	0
Net pension benefit or post-retirement costs	$ 1,028	$ 1,578	$ 1,177

Pension and Post-Retirement Benefits - Changes in Benefit Obligations and Plan Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, beginning balance	$ 115,420	$ 122,336
Service cost	1,078	1,295	$ 1,080
Interest cost	4,067	4,813	4,811
Actuarial (gain) loss	1,640	(7,492)
Benefits paid	(6,517)	(6,106)
Amendments	457	574
Special termination benefit	0	0
Other	0	0
Benefit obligation, ending balance	116,145	115,420	122,336
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, beginning balance	84,716	90,897
Actual return on plan assets	5,651	(2,100)
Employer contributions	0	2,025
Benefits paid	(6,517)	(6,106)
Other	0	0
Fair value of plan assets, ending balance	83,850	84,716	90,897
Plan assets less than benefit obligations at December 31 recognized as liability for pension and other post-retirement benefits	(32,295)	(30,704)
Post-retirement Benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, beginning balance	25,091	28,289
Service cost	132	176	151
Interest cost	876	1,074	1,030
Actuarial (gain) loss	(802)	(3,631)
Benefits paid	(1,332)	(1,288)
Amendments	0	0
Special termination benefit	21	48
Other	407	423
Benefit obligation, ending balance	24,393	25,091	28,289
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, beginning balance	17	19
Actual return on plan assets	(3)	(2)
Employer contributions	925	864
Benefits paid	(1,332)	(1,288)
Other	407	424
Fair value of plan assets, ending balance	14	17	$ 19
Plan assets less than benefit obligations at December 31 recognized as liability for pension and other post-retirement benefits	$ (24,379)	$ (25,074)

Pension and Post-Retirement Benefits - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Plans, Postretirement and Other Employee Benefits
Projected benefit obligation, nonqualified pension plan	$ 1.6	$ 1.6
Defined benefit plan, pension plans with accumulated benefit obligations in excess of plan assets, aggregate accumulated benefit obligation	1.6	1.6
Fair value of plan assets, nonqualified pension plan	0.0	0.0
Defined benefit plan, accumulated other comprehensive income net gains (losses), after tax	(13.8)	$ (14.1)
Defined benefit plan, accumulated other comprehensive income net prior service cost (credit), after tax	$ 1.8
Percentage of contributions to individual multiemployer pension funds	5.00%	5.00%	5.00%
Company contribution over defined benefit plan	4.00%
Company contributing percentage on defined benefit plan	25.00%
Employee contribution over defined benefit plan	8.00%
Company contributions to defined contribution plan	$ 2.4	$ 2.8	$ 2.1
Pension Benefits
Pension Plans, Postretirement and Other Employee Benefits
Accumulated benefit obligation	116.0	$ 115.3
Expected contributions to the plans for fiscal year	2.1
Post-retirement Benefits
Pension Plans, Postretirement and Other Employee Benefits
Expected contributions to the plans for fiscal year	$ 1.4
Certain Employees
Pension Plans, Postretirement and Other Employee Benefits
Employee contribution over defined benefit plan	8.00%
Company contribution on profit sharing match	25.00%
Other Employees
Pension Plans, Postretirement and Other Employee Benefits
Company contribution on profit sharing match	25.00%

Pension and Post-Retirement Benefits - Estimated Future Pension and Post-Retirement Benefit Payments (Detail) $ in Thousands	Dec. 31, 2016 USD ($)
Pension Benefits
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2017	$ 6,824
2018	7,050
2019	7,201
2020	7,343
2021	7,419
2022-2026	38,158
Post-retirement Benefits \| Before Medicare Subsidy
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2017	1,570
2018	1,544
2019	1,521
2020	1,598
2021	1,676
2022-2026	8,627
Post-retirement Benefits \| After Medicare Subsidy
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2017	1,429
2018	1,402
2019	1,379
2020	1,452
2021	1,528
2022-2026	$ 7,839

Pension and Post-Retirement Benefits - Amounts in Accumulated Other Comprehensive Income Expected to be Recognized as Components of Net Periodic Benefit Cost (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
Pension Plans, Postretirement and Other Employee Benefits
Net actuarial loss	$ 1,372
Prior service cost	411
Total	1,783
Pension Benefits
Pension Plans, Postretirement and Other Employee Benefits
Net actuarial loss	1,372
Prior service cost	411
Total	1,783
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 - Company's Obligations Determined under Weighted-Average Assumptions (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Pension Benefits
Pension Plans, Postretirement and Other Employee Benefits
Discount rate	4.20%	4.50%
Long-term rate of compensation increase	3.50%	3.50%
Long-term rate of return on plan assets	7.00%	7.00%
Post-retirement Benefits
Pension Plans, Postretirement and Other Employee Benefits
Discount rate	4.20%	4.50%
Long-term rate of return on plan assets	7.00%	7.00%
Post-retirement Benefits \| Pre-65
Pension Plans, Postretirement and Other Employee Benefits
Ultimate rate	5.00%	5.00%
Post-retirement Benefits \| Pre-65 \| Maximum
Pension Plans, Postretirement and Other Employee Benefits
Initial rate	7.30%	7.80%
Post-retirement Benefits \| Post-65
Pension Plans, Postretirement and Other Employee Benefits
Ultimate rate	5.00%	5.00%
Post-retirement Benefits \| Post-65 \| Minimum
Pension Plans, Postretirement and Other Employee Benefits
Initial rate	8.50%	9.00%

Pension and Post-Retirement Benefits - Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
Compensation and Retirement Disclosure [Abstract]
Effect on total of service and interest cost, increase	$ 144
Effect on post-retirement benefit obligation, increase	2,827
Effect on total of service and interest cost, decrease	(120)
Effect on post-retirement benefit obligation, decrease	$ (2,406)

Pension and Post-Retirement Benefits - Fair Value of Pension Plan Assets (Detail)	Dec. 31, 2016	Dec. 31, 2015
Pension Benefits \| Equity securities
Pension Plans, Postretirement and Other Employee Benefits
Percentage of the fair value of the total plan assets	59.40%	58.10%
Pension Benefits \| Debt securities
Pension Plans, Postretirement and Other Employee Benefits
Percentage of the fair value of the total plan assets	38.30%	40.00%
Pension Benefits \| Cash
Pension Plans, Postretirement and Other Employee Benefits
Percentage of the fair value of the total plan assets	2.30%	1.90%
Post-retirement Benefits \| Equity securities
Pension Plans, Postretirement and Other Employee Benefits
Percentage of the fair value of the total plan assets	64.00%	52.50%
Post-retirement Benefits \| Debt securities
Pension Plans, Postretirement and Other Employee Benefits
Percentage of the fair value of the total plan assets	39.10%	35.30%
Post-retirement Benefits \| Cash
Pension Plans, Postretirement and Other Employee Benefits
Percentage of the fair value of the total plan assets	(3.10%)	12.20%

Pension and Post-Retirement Benefits - Summary of Multiemployer Pension Plan (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
LIUNA
Pension Plans, Postretirement and Other Employee Benefits
EIN/ Pension Plan No.	52-6074345/001
Pension Protection Act Zone Status	Red	Red
Company Contributions (in thousands)	$ 167,000	$ 182,000	$ 149,000
Surcharge Imposed	Yes
Expiration Date of CBA	May 31, 2017
IUOE
Pension Plans, Postretirement and Other Employee Benefits
EIN/ Pension Plan No.	36-6052390/001
Pension Protection Act Zone Status	Green	Green
Company Contributions (in thousands)	$ 28,000	$ 29,000	28,000
Surcharge Imposed	No
Expiration Date of CBA	Jul. 29, 2018
CSSS
Pension Plans, Postretirement and Other Employee Benefits
EIN/ Pension Plan No.	36-6044243/001
Pension Protection Act Zone Status	Red	Red
Company Contributions (in thousands)	$ 51,000	$ 51,000	$ 51,000
Surcharge Imposed	NA
Central States, Southeast and Southwest Areas Pension Plan
Pension Plans, Postretirement and Other Employee Benefits
Withdrawal liability from pension plan	$ 1,000,000
Withdrawal liability paid on monthly installments	$ 4,000

Income Taxes - Summary of Income Tax (Expense) Benefit (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current:
Federal									$ 60	$ (170)	$ (34,790)
State									(274)	1,448	(4,835)
Current income tax total									(214)	1,278	(39,625)
Deferred:
Federal									32,944	7,439	(308)
State									3,959	3,034	2,750
Deferred income tax total									36,903	10,473	2,442
Income tax benefit (expense)	$ 6,588	$ 12,177	$ 9,774	$ 8,150	$ 4,167	$ 4,695	$ 6,342	$ (3,453)	$ 36,689	$ 11,751	$ (37,183)

Income Taxes - Summary of Tax Effects on Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Gross deferred tax assets:
Net operating loss carry forward and state tax credits	$ 65,022	$ 39,280
Pension and post-retirement benefit costs	22,920	22,577
Alternative minimum tax credit carry forward	19,431	19,049
Property, plant and equipment	6,112	6,657
Accrued expenses	6,752	3,765
Inventories	4,362	6,425
Third-party products liability	511	568
Stock-based compensation expense	5,576	3,365
Note payable	4,009	0
Other	5,458	5,373
Deferred Tax Assets, Gross	140,153	107,059
Gross deferred tax liabilities:
Land and mineral property basis difference	(126,315)	(63,488)
Fixed assets and depreciation	(61,531)	(54,913)
Intangibles	(2,260)	(8,049)
Other	(122)	(122)
Total deferred tax liabilities	(190,228)	(126,572)
Net deferred tax liabilities	$ (50,075)	$ (19,513)

Income Taxes - Operating Loss Carryforwards (Details) - IRS $ in Millions	Dec. 31, 2016 USD ($)
Operating Loss Carryforwards [Line Items]
Federal net operating loss carryforwards	$ 170.4
Cadre Services, Inc.
Operating Loss Carryforwards [Line Items]
Federal net operating loss carryforwards	$ 69.0

Income Taxes - Additional Information (Detail) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Alternative minimum tax credit carry forward	$ 19,400,000	$ 19,000,000
Unrecognized tax benefits	$ 0	$ 0

Income Taxes - Summary of Effective Income Tax Rate on Pretax Earnings (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income tax benefit (expense) computed at U.S. federal statutory rate									$ 27,211	$ (41)	$ (55,553)
Decrease (increase) resulting from:
Statutory depletion									4,734	8,918	15,548
Prior year tax return reconciliation									435	393	1,018
State income taxes, net of federal benefit									2,369	1,370	(3,416)
Domestic production deduction									0	0	3,911
Equity compensation									2,003	0	0
Other, net									(63)	1,111	1,309
Income tax benefit (expense)	$ 6,588	$ 12,177	$ 9,774	$ 8,150	$ 4,167	$ 4,695	$ 6,342	$ (3,453)	$ 36,689	$ 11,751	$ (37,183)

Obligations Under Guarantees (Detail) - Travelers Casualty and Surety Company $ in Millions	Dec. 31, 2016 USD ($)
Surety Bonds
Loss Contingencies
Surety bonds outstanding	$ 10.5
Reclamation Bonds
Loss Contingencies
Bonds related to reclamation requirements	$ 10.1

Segment Reporting - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) Segment Product	Dec. 31, 2015 USD ($)
Segment Reporting Information
Number of reportable segments \| Segment	2
Number of products \| Product	215
Goodwill	$ 240,975	$ 68,647
Operating Segments \| Oil & Gas Proppants
Segment Reporting Information
Goodwill	220,300
Operating Segments \| Industrial & Specialty Products
Segment Reporting Information
Goodwill	$ 20,700

Segment Reporting - Presentation of Sales and Segment Contribution Margin for Reporting Segments and Other Operating Results (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information
Sales	$ 182,373	$ 137,748	$ 116,994	$ 122,510	$ 136,112	$ 155,408	$ 147,511	$ 203,958	$ 559,625	$ 642,989	$ 876,741
Selling, general and administrative	(19,167)	(18,472)	(14,585)	(15,503)	(15,682)	(13,559)	(6,575)	(26,961)	(67,727)	(62,777)	(88,971)
Depreciation, depletion and amortization	(21,194)	(17,175)	(15,209)	(14,556)	(16,378)	(15,158)	(13,695)	(13,243)	(68,134)	(58,474)	(45,019)
Interest expense	(7,998)	(6,684)	(6,647)	(6,643)	(6,835)	(6,684)	(6,928)	(6,836)
Income tax benefit (expense)	6,588	12,177	9,774	8,150	4,167	4,695	6,342	(3,453)	36,689	11,751	(37,183)
Net income (loss)	$ (6,942)	$ (11,339)	$ (11,772)	$ (11,003)	$ (15,320)	$ 2,412	$ 9,953	$ 14,823	(41,056)	11,868	121,540
Operating Segments
Segment Reporting Information
Sales									559,625	642,989	876,741
Total segment contribution margin									90,433	159,065	317,239
Operating Segments \| Oil & Gas Proppants
Segment Reporting Information
Sales									362,550	430,435	662,770
Total segment contribution margin									11,445	88,928	256,137
Operating Segments \| Industrial & Specialty Products
Segment Reporting Information
Sales									197,075	212,554	213,971
Total segment contribution margin									78,988	70,137	61,102
Segment Reconciling Items
Segment Reporting Information
Operating activities excluded from segment cost of goods sold									(8,103)	(11,142)	(7,082)
Selling, general and administrative									(67,727)	(62,777)	(88,971)
Depreciation, depletion and amortization									(68,134)	(58,474)	(45,019)
Interest expense									(27,972)	(27,283)	(18,202)
Other income, net, including interest income									$ 3,758	$ 728	$ 758

Unaudited Supplementary Data (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands					3 Months Ended								12 Months Ended
	Nov. 03, 2016	Jul. 21, 2016	May 05, 2016	Feb. 22, 2016	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Sales					$ 182,373	$ 137,748	$ 116,994	$ 122,510	$ 136,112	$ 155,408	$ 147,511	$ 203,958	$ 559,625	$ 642,989	$ 876,741
Cost of goods sold (excluding depreciation, depletion and amortization)					148,411	119,426	102,707	106,751	116,614	122,599	117,200	138,653	477,295	495,066	566,584
Operating expenses
Selling, general and administrative					19,167	18,472	14,585	15,503	15,682	13,559	6,575	26,961	67,727	62,777	88,971
Depreciation, depletion and amortization					21,194	17,175	15,209	14,556	16,378	15,158	13,695	13,243	68,134	58,474	45,019
Total operating expenses					40,361	35,647	29,794	30,059	32,060	28,717	20,270	40,204	135,861	121,251	133,990
Operating income (loss)					(6,399)	(17,325)	(15,507)	(14,300)	(12,562)	4,092	10,041	25,101	(53,531)	26,672	176,167
Other income (expense)
Interest expense					(7,998)	(6,684)	(6,647)	(6,643)	(6,835)	(6,684)	(6,928)	(6,836)
Other income, net, including interest income					867	493	608	1,790	(90)	309	498	11	3,758	728	758
Total other (expenses) income					(7,131)	(6,191)	(6,039)	(4,853)	(6,925)	(6,375)	(6,430)	(6,825)	(24,214)	(26,555)	(17,444)
Income (loss) before income taxes					(13,530)	(23,516)	(21,546)	(19,153)	(19,487)	(2,283)	3,611	18,276	(77,745)	117	158,723
Income tax benefit (expense)					6,588	12,177	9,774	8,150	4,167	4,695	6,342	(3,453)	36,689	11,751	(37,183)
Net income (loss)					$ (6,942)	$ (11,339)	$ (11,772)	$ (11,003)	$ (15,320)	$ 2,412	$ 9,953	$ 14,823	$ (41,056)	$ 11,868	$ 121,540
Earnings (loss) per share, basic (in usd per share)					$ (0.09)	$ (0.17)	$ (0.19)	$ (0.20)	$ (0.29)	$ 0.05	$ 0.19	$ 0.28	$ (0.63)	$ 0.22	$ 2.26
Earnings (loss) per share, diluted (in usd per share)					$ (0.09)	$ (0.17)	$ (0.19)	$ (0.20)	$ (0.29)	$ 0.04	$ 0.18	$ 0.28	$ (0.63)	$ 0.22	$ 2.24
Weighted average common shares outstanding, basic (in shares)					75,539	66,676	63,417	54,470	53,323	53,321	53,303	53,416	65,037	53,344	53,719
Weighted average common shares outstanding, diluted (in shares)					75,539	66,676	63,417	54,470	53,323	53,742	53,857	53,869
Dividend declared per share (in usd per share)	$ 0.0625	$ 0.0625	$ 0.0625	$ 0.0625	$ 0.0625	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.125	$ 0.125	$ 0.125	$ 0.25	$ 0.438	$ 0.50

Parent Company Financials - Balance Sheet - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current Assets:
Cash and cash equivalents	$ 711,225	$ 277,077	$ 263,066	$ 73,597
Short-term investments	0	21,849
Total current assets	892,945	439,140
Total assets	2,073,220	1,108,619
Current Liabilities:
Dividends payable	5,221	3,453
Total current liabilities	109,960	83,918
Deferred income taxes, net	50,075	19,513
Total liabilities	799,930	724,452
Stockholders’ Equity:
Preferred stock	0	0
Common stock	811	539
Additional paid-in capital	1,129,051	194,670
Retained earnings	163,173	220,974
Treasury stock, at cost	(3,869)	(15,845)
Accumulated other comprehensive loss	(15,876)	(16,171)
Total stockholders’ equity	1,273,290	384,167	403,816	309,294
Total liabilities and stockholders’ equity	2,073,220	1,108,619
Parent Company
Current Assets:
Cash and cash equivalents	534,378	58,579	47,292	69,623
Short-term investments	0	21,849
Total current assets	534,378	80,428
Investment in subsidiaries	854,860	417,462
Total assets	1,389,238	497,890
Current Liabilities:
Accrued expenses and other current liabilities	461	107
Dividends payable	5,222	3,453
Due to affiliates	110,265	110,159
Total current liabilities	115,948	113,719
Deferred income taxes, net	0	4
Total liabilities	115,948	113,723
Stockholders’ Equity:
Preferred stock	0	0
Common stock	811	539
Additional paid-in capital	1,129,051	194,670
Retained earnings	163,173	220,974
Treasury stock, at cost	(3,869)	(15,845)
Accumulated other comprehensive loss	(15,876)	(16,171)
Total stockholders’ equity	1,273,290	384,167	$ 403,816	$ 309,294
Total liabilities and stockholders’ equity	$ 1,389,238	$ 497,890

Parent Company Financials- Income Statement (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Income (Loss) [Abstract]
Revenue	$ 182,373	$ 137,748	$ 116,994	$ 122,510	$ 136,112	$ 155,408	$ 147,511	$ 203,958	$ 559,625	$ 642,989	$ 876,741
Cost of revenue	148,411	119,426	102,707	106,751	116,614	122,599	117,200	138,653	477,295	495,066	566,584
Operating expenses
Selling, general and administrative	19,167	18,472	14,585	15,503	15,682	13,559	6,575	26,961	67,727	62,777	88,971
Total operating expenses	40,361	35,647	29,794	30,059	32,060	28,717	20,270	40,204	135,861	121,251	133,990
Operating income (loss)	(6,399)	(17,325)	(15,507)	(14,300)	(12,562)	4,092	10,041	25,101	(53,531)	26,672	176,167
Other income (expense)
Interest income									(27,972)	(27,283)	(18,202)
Other income, net, including interest income	867	493	608	1,790	(90)	309	498	11	3,758	728	758
Total other (expenses) income	(7,131)	(6,191)	(6,039)	(4,853)	(6,925)	(6,375)	(6,430)	(6,825)	(24,214)	(26,555)	(17,444)
Income tax benefit (expense)	6,588	12,177	9,774	8,150	4,167	4,695	6,342	(3,453)	36,689	11,751	(37,183)
Net income (loss)	$ (6,942)	$ (11,339)	$ (11,772)	$ (11,003)	$ (15,320)	$ 2,412	$ 9,953	$ 14,823	(41,056)	11,868	121,540
Other comprehensive income (loss), net of deferred income taxes:
Unrealized gain (loss) on investments (net of tax of ($4), $29 and ($8) for 2016, 2015, and 2014, respectively)									(6)	47	(14)
Unrealized gain (loss) on derivatives (net of tax of $29, $34 and ($32) for 2016, 2015, and 2014, respectively)									49	53	(55)
Pension and other post-retirement benefits liability adjustment (net of tax of $152, $2,469 and ($9,678) for 2016, 2015, and 2014, respectively)									252	3,547	(15,732)
Comprehensive income									(40,761)	15,515	105,739
Pension and post-retirement liability									252	3,547	(15,732)
Tax expense (benefit) on unrealized gain (loss) on investments									(4)	29	(8)
Tax expense (benefit) on unrealized gain (loss) on derivatives									29	34	(32)
Tax expense (benefit) on pension and other post-retirement benefits liability adjustment									152	2,469	(9,678)
Parent Company
Operating Income (Loss) [Abstract]
Revenue									0	0	0
Cost of revenue									0	0	0
Operating expenses
Selling, general and administrative									184	185	184
Other									10	19	0
Total operating expenses									194	204	184
Operating income (loss)									(194)	(204)	(184)
Other income (expense)
Interest income									1,046	262	278
Early extinguishment of debt									0	0	0
Other income, net, including interest income									0	1	0
Total other (expenses) income									1,046	263	278
Income before income taxes and equity in net earnings of subsidiaries									852	59	94
Income tax benefit (expense)									(344)	(24)	(38)
Income before equity in net earnings of subsidiaries									508	35	56
Equity in earnings of subsidiaries, net of tax									(41,564)	11,833	121,484
Net income (loss)									(41,056)	11,868	121,540
Other comprehensive income (loss), net of deferred income taxes:
Unrealized gain (loss) on investments (net of tax of ($4), $29 and ($8) for 2016, 2015, and 2014, respectively)									(6)	47	(14)
Unrealized gain (loss) on derivatives (net of tax of $29, $34 and ($32) for 2016, 2015, and 2014, respectively)									49	53	(55)
Pension and other post-retirement benefits liability adjustment (net of tax of $152, $2,469 and ($9,678) for 2016, 2015, and 2014, respectively)									252	3,547	(15,732)
Other comprehensive income (loss), net of deferred income taxes									295	3,647	(15,801)
Comprehensive income									(40,761)	15,515	105,739
Pension and post-retirement liability									252	3,547	(15,732)
Tax expense (benefit) on unrealized gain (loss) on investments									(4)	29	(8)
Tax expense (benefit) on unrealized gain (loss) on derivatives									29	34	(32)
Tax expense (benefit) on pension and other post-retirement benefits liability adjustment									$ 152	$ 2,469	$ (9,678)

Parent Company Financials - Statement of Equity (Details) - USD ($)					1 Months Ended		3 Months Ended								12 Months Ended
	Nov. 03, 2016	Jul. 21, 2016	May 05, 2016	Feb. 22, 2016	Nov. 30, 2016	Mar. 31, 2016	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Beginning balance										$ 384,167,000				$ 403,816,000	$ 384,167,000	$ 403,816,000	$ 309,294,000
Net income (loss)							$ (6,942,000)	$ (11,339,000)	$ (11,772,000)	$ (11,003,000)	$ (15,320,000)	$ 2,412,000	$ 9,953,000	$ 14,823,000	(41,056,000)	11,868,000	121,540,000
Issuance of common stock (stock offerings net of issuance costs of $25,732)					$ 467,000,000	$ 186,200,000									931,288,000
Unrealized gain (loss) on derivatives															49,000	53,000	(55,000)
Unrealized gain (loss) on short-term investments															(6,000)	47,000	(14,000)
Pension and post-retirement liability															252,000	3,547,000	(15,732,000)
Cash dividends declared ($0.25, $0.438 and $0.500 per share of common stock for 2016, 2015 and 2014 respectively))															(16,893,000)	(23,445,000)	(26,967,000)
Equity-based compensation															12,107,000	3,857,000	7,487,000
Excess tax benefit from equity-based compensation															148,000		3,813,000
Proceeds from options exercised															4,825,000	473,000	5,563,000
Issuance of restricted stock															0
Shares withheld for employee taxes related to vested restricted stock and stock units															(1,591,000)	(794,000)	(614,000)
Repurchase of common stock																(15,255,000)	(499,000)
Ending balance							$ 1,273,290,000				$ 384,167,000				$ 1,273,290,000	$ 384,167,000	$ 403,816,000
Dividend declared per share (in usd per share)	$ 0.0625	$ 0.0625	$ 0.0625	$ 0.0625			$ 0.0625	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.125	$ 0.125	$ 0.125	$ 0.25	$ 0.438	$ 0.50
Common stock issuance costs															$ 25,732
Common Stock
Beginning balance										$ 539,000				$ 539,000	539,000	$ 539,000	$ 534,000
Issuance of common stock (stock offerings net of issuance costs of $25,732)															272,000
Proceeds from options exercised																	4,000
Shares withheld for employee taxes related to vested restricted stock and stock units																	1,000
Ending balance							$ 811,000				$ 539,000				811,000	539,000	539,000
Treasury Stock
Beginning balance										(15,845,000)				(542,000)	(15,845,000)	(542,000)	0
Proceeds from options exercised															8,465,000	744,000	572,000
Issuance of restricted stock															1,437,000
Shares withheld for employee taxes related to vested restricted stock and stock units															2,074,000	(792,000)	(615,000)
Repurchase of common stock																(15,255,000)	(499,000)
Ending balance							(3,869,000)				(15,845,000)				(3,869,000)	(15,845,000)	(542,000)
Additional Paid-In Capital
Beginning balance										194,670,000				191,086,000	194,670,000	191,086,000	174,799,000
Issuance of common stock (stock offerings net of issuance costs of $25,732)															931,016,000
Equity-based compensation															12,107,000	3,857,000	7,487,000
Excess tax benefit from equity-based compensation																	3,813,000
Proceeds from options exercised															(3,640,000)	(271,000)	4,987,000
Issuance of restricted stock															(1,437,000)
Shares withheld for employee taxes related to vested restricted stock and stock units															(3,665,000)	(2,000)	0
Ending balance							1,129,051,000				194,670,000				1,129,051,000	194,670,000	191,086,000
Retained Earnings
Beginning balance										220,974,000				232,551,000	220,974,000	232,551,000	137,978,000
Net income (loss)															(41,056,000)	11,868,000	121,540,000
Cash dividends declared ($0.25, $0.438 and $0.500 per share of common stock for 2016, 2015 and 2014 respectively))															(16,893,000)	(23,445,000)	(26,967,000)
Excess tax benefit from equity-based compensation															148,000
Ending balance							163,173,000				220,974,000				163,173,000	220,974,000	232,551,000
Accumulated Other Comprehensive (Loss)
Beginning balance										(16,171,000)				(19,818,000)	(16,171,000)	(19,818,000)	(4,017,000)
Unrealized gain (loss) on derivatives															49,000	53,000	(55,000)
Unrealized gain (loss) on short-term investments															(6,000)	47,000	(14,000)
Pension and post-retirement liability															252,000	3,547,000	(15,732,000)
Ending balance							(15,876,000)				(16,171,000)				(15,876,000)	(16,171,000)	(19,818,000)
Parent Company
Beginning balance										384,167,000				403,816,000	384,167,000	403,816,000	309,294,000
Net income (loss)															(41,056,000)	11,868,000	121,540,000
Issuance of common stock (stock offerings net of issuance costs of $25,732)															931,288,000
Unrealized gain (loss) on derivatives															49,000	53,000	(55,000)
Unrealized gain (loss) on short-term investments															(6,000)	47,000	(14,000)
Pension and post-retirement liability															252,000	3,547,000	(15,732,000)
Cash dividends declared ($0.25, $0.438 and $0.500 per share of common stock for 2016, 2015 and 2014 respectively))															(16,893,000)	(23,445,000)	(26,967,000)
Equity-based compensation															12,107,000	3,857,000	7,487,000
Excess tax benefit from equity-based compensation															148,000		3,813,000
Proceeds from options exercised															4,825,000	473,000	5,563,000
Issuance of restricted stock															0
Shares withheld for employee taxes related to vested restricted stock and stock units															(1,591,000)	(794,000)	(614,000)
Repurchase of common stock																(15,255,000)	(499,000)
Ending balance							1,273,290,000				384,167,000				$ 1,273,290,000	$ 384,167,000	$ 403,816,000
Dividend declared per share (in usd per share)															$ 0.25	$ 0.438	$ 0.500
Common stock issuance costs															$ 25,732
Parent Company \| Common Stock
Beginning balance										539,000				539,000	539,000	$ 539,000	$ 534,000
Issuance of common stock (stock offerings net of issuance costs of $25,732)															272,000
Proceeds from options exercised																	4,000
Shares withheld for employee taxes related to vested restricted stock and stock units																	1,000
Ending balance							811,000				539,000				811,000	539,000	539,000
Parent Company \| Treasury Stock
Beginning balance										(15,845,000)				(542,000)	(15,845,000)	(542,000)	0
Proceeds from options exercised															8,465,000	744,000	572,000
Issuance of restricted stock															1,437,000
Shares withheld for employee taxes related to vested restricted stock and stock units															2,074,000	(792,000)	(615,000)
Repurchase of common stock																(15,255,000)	(499,000)
Ending balance							(3,869,000)				(15,845,000)				(3,869,000)	(15,845,000)	(542,000)
Parent Company \| Additional Paid-In Capital
Beginning balance										194,670,000				191,086,000	194,670,000	191,086,000	174,799,000
Issuance of common stock (stock offerings net of issuance costs of $25,732)															931,016,000
Equity-based compensation															12,107,000	3,857,000	7,487,000
Excess tax benefit from equity-based compensation																	3,813,000
Proceeds from options exercised															(3,640,000)	(271,000)	4,987,000
Issuance of restricted stock															(1,437,000)
Shares withheld for employee taxes related to vested restricted stock and stock units															(3,665,000)	(2,000)
Ending balance							1,129,051,000				194,670,000				1,129,051,000	194,670,000	191,086,000
Parent Company \| Retained Earnings
Beginning balance										220,974,000				232,551,000	220,974,000	232,551,000	137,978,000
Net income (loss)															(41,056,000)	11,868,000	121,540,000
Cash dividends declared ($0.25, $0.438 and $0.500 per share of common stock for 2016, 2015 and 2014 respectively))															(16,893,000)	(23,445,000)	(26,967,000)
Excess tax benefit from equity-based compensation															148,000
Ending balance							163,173,000				220,974,000				163,173,000	220,974,000	232,551,000
Parent Company \| Accumulated Other Comprehensive (Loss)
Beginning balance										$ (16,171,000)				$ (19,818,000)	(16,171,000)	(19,818,000)	(4,017,000)
Unrealized gain (loss) on derivatives															49,000	53,000	(55,000)
Unrealized gain (loss) on short-term investments															(6,000)	47,000	(14,000)
Pension and post-retirement liability															252,000	3,547,000	(15,732,000)
Ending balance							$ (15,876,000)				$ (16,171,000)				$ (15,876,000)	$ (16,171,000)	$ (19,818,000)

Parent Company Financials - Statement of Cash Flow (Details) - USD ($) $ in Thousands	3 Months Ended									12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Mar. 31, 2013	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities:
Net income (loss)	$ (6,942)	$ (11,339)	$ (11,772)	$ (11,003)	$ (15,320)	$ 2,412	$ 9,953	$ 14,823		$ (41,056)	$ 11,868	$ 121,540
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Other										3,643	(5,257)	367
Accounts payable and accrued liabilities										13,121	(42,353)	51,357
Net cash provided by (used in) operating activities										381	61,492	171,411
Investing activities:
Proceeds from sales and maturities of short-term investments										21,872	53,568	0
Net cash provided by (used in) investing activities										(201,657)	49	(190,906)
Financing activities:
Dividends paid										(15,125)	(26,797)	(26,871)
Repurchase of common stock										0	(15,255)	(499)
Proceeds from options exercised										4,825	473	5,563
Tax payments related to shares withheld for vested restricted stock and stock units										(1,591)	(794)	(614)
Issuance of common stock									$ 0	678,791	0
Common stock issuance costs									$ 0	(25,732)	0
Net cash provided by (used in) financing activities										635,424	(47,530)	208,964
Net increase in cash and cash equivalents										434,148	14,011	189,469
Cash and cash equivalents, beginning of period				277,077				263,066		277,077	263,066	73,597
Cash and cash equivalents, end of period	711,225				277,077					711,225	277,077	263,066
Cash paid (received) during the period for:
Interest										21,994	21,729	15,920
Common stock issued for business acquisitions										165	0	0
Parent Company
Operating activities:
Net income (loss)										(41,056)	11,868	121,540
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Undistributed (Income) loss from equity method investment, net										41,564	(11,833)	(121,484)
Other										(30)	(195)	(213)
Accounts payable and accrued liabilities										353	29	36
Net cash provided by (used in) operating activities										831	(131)	(121)
Investing activities:
Proceeds from sales and maturities of short-term investments										21,872	53,568	0
Investment in subsidiary										(188,177)	0	0
Net cash provided by (used in) investing activities										(166,305)	53,568	0
Financing activities:
Dividends paid										(15,125)	(26,797)	(26,871)
Repurchase of common stock										0	(15,255)	(499)
Proceeds from options exercised										4,603	473	5,563
Tax payments related to shares withheld for vested restricted stock and stock units										(1,590)	(794)	(614)
Issuance of common stock										678,791	0	0
Issuance of treasury stock										221	0	0
Common stock issuance costs										(25,733)	0	0
Net financing activities with subsidiaries										106	223	211
Net cash provided by (used in) financing activities										641,273	(42,150)	(22,210)
Net increase in cash and cash equivalents										475,799	11,287	(22,331)
Cash and cash equivalents, beginning of period				$ 58,579				$ 47,292		58,579	47,292	69,623
Cash and cash equivalents, end of period	$ 534,378				$ 58,579					534,378	58,579	47,292
Cash paid (received) during the period for:
Interest										(1,046)	(263)	(278)
Common stock issued for business acquisitions										$ 278,229	$ 0	$ 0

Subsequent Events (Detail) - USD ($) $ / shares in Units, $ in Millions							3 Months Ended								12 Months Ended
	Feb. 16, 2017	Jan. 05, 2017	Nov. 03, 2016	Jul. 21, 2016	May 05, 2016	Feb. 22, 2016	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Subsequent Event
Common stock cash dividend declared, per share			$ 0.0625	$ 0.0625	$ 0.0625	$ 0.0625	$ 0.0625	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.125	$ 0.125	$ 0.125	$ 0.25	$ 0.438	$ 0.50
Reduction in provision for income taxes															$ 2.2
Subsequent Event
Subsequent Event
Cash dividend paid		$ 0.0625
Common stock cash dividend declared, per share	$ 0.0625

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2016
Subsequent Events [Abstract]
Subsequent Events	NOTE V—SUBSEQUENT EVENTS On January 5, 2017, we paid a cash dividend of $0.0625 per share to common stockholders of record on December 15, 2016, as had been declared by our Board of Directors on November 7, 2016. On February 16, 2017, our Board of Directors declared a quarterly cash dividend of $0.0625 per share to common stockholders of record at the close of business on March 15, 2017, payable on April 5, 2017.

Organization - (Detail)	12 Months Ended
Organization - (Detail)	Dec. 31, 2016 Segment
Organization And Nature Of Business
Number of business segments	2