View Filing Data

In thousands

Three Months Ended
March 31,

Stock options excluded

Restricted stock and performance share units awards excluded

Accounts Receivable (Tables)

3 Months Ended

Mar. 31, 2020

Schedule of Accounts Receivable and Allowance for Doubtful Accounts

The following table is a rollforward of the allowance for credit losses (in thousands) for the three months ended March 31, 2020 disaggregated by portfolio segments:



	Oil & Gas Proppants		Industrial & Specialty Products			Total
Beginning balance, December 31, 2019	$	7,640	$	1,344		$	8,984
Provision for credit losses	840		62			902
Write-offs	—		(287		)	(287		)
Ending balance, March 31, 2020	$	8,480	$	1,119		$	9,599

At March 31, 2020 and December 31, 2019, accounts receivable (in thousands) consisted of the following:



	March 31, 2020			December 31, 2019
Trade receivables	$	193,372		$	178,182
Less: Allowance for credit losses	(9,599		)	(8,984		)
Net trade receivables	183,773			169,198
Other receivables⁽¹⁾	49,082			13,040
Total accounts receivable	$	232,855		$	182,238



(1	)	At March 31, 2020, other receivables included $16.1 million of refundable alternative minimum tax credits and $28 million of refunds attributable to the CARES Act provision for net operating loss ("NOL") carrybacks from 2014-2019. At December 31, 2019, other receivables included $8.1 million of refundable alternative minimum tax credits.

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current Assets:
Cash and cash equivalents	$ 144,701	$ 185,740
Accounts receivable, net	232,855	182,238
Inventories, net	119,084	124,432
Prepaid expenses and other current assets	17,926	16,155
Income tax deposits	0	475
Total current assets	514,566	509,040
Property, plant and mine development, net	1,487,221	1,517,587
Operating lease right-of-use assets	48,847	53,098
Goodwill	185,649	273,524
Intangible assets, net	181,597	183,815
Other assets	15,244	16,170
Total assets	2,433,124	2,553,234
Current Liabilities:
Accounts payable and accrued expenses	196,959	248,237
Current portion of operating lease liabilities	50,402	53,587
Current portion of long-term debt	40,233	18,463
Current portion of deferred revenue	9,799	15,111
Total current liabilities	297,393	335,398
Long-term debt, net	1,212,264	1,213,985
Deferred revenue	38,310	35,523
Liability for pension and other post-retirement benefits	65,475	58,453
Deferred income taxes, net	33,940	38,585
Operating lease liabilities	108,741	117,964
Other long-term obligations	37,407	36,746
Total liabilities	1,793,530	1,836,654
Commitments and Contingencies (Note O)
Stockholders’ Equity:
Preferred stock, $0.01 par value, 10,000,000 shares authorized; zero issued and outstanding at March 31, 2020 and December 31, 2019	0	0
Common stock, $0.01 par value, 500,000,000 shares authorized; 82,835,684 issued and 73,757,495 outstanding at March 31, 2020; 82,601,926 issued and 73,601,950 outstanding at December 31, 2019	824	823
Additional paid-in capital	1,187,962	1,185,116
Retained deficit	(353,862)	(279,956)
Treasury stock, at cost, 9,078,189 and 8,999,976 shares at March 31, 2020 and December 31, 2019, respectively	(181,369)	(180,912)
Accumulated other comprehensive loss	(25,060)	(19,854)
Total U.S. Silica Holdings, Inc. stockholders’ equity	628,495	705,217
Non-controlling interest	11,099	11,363
Total stockholders' equity	639,594	716,580
Total liabilities and stockholders’ equity	$ 2,433,124	$ 2,553,234

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net loss	$ (72,605)	$ (19,328)
Other comprehensive loss:
Unrealized gain (loss) on derivatives (net of tax of $67 and ($299) for the three months ended March 31, 2020 and 2019, respectively)	211	(940)
Foreign currency translation adjustment (net of tax of $(92) and $(60) for the three months ended March 31, 2020 and 2019, respectively)	(289)	(199)
Pension and other post-retirement benefits liability adjustment (net of tax of $(1,634) and $55 for the three months ended March 31, 2020 and 2019, respectively)	(5,128)	174
Comprehensive loss	(77,811)	(20,293)
Less: Comprehensive loss attributable to non-controlling interest	(260)	(4)
Comprehensive loss attributable to U.S. Silica Holdings, Inc.	$ (77,551)	$ (20,289)

- Definition

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

+ References

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Reference 6: http://www.xbrl.org/2003/role/exampleRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=116874947&loc=SL4591552-111686

+ Details

Capital Structure and Accumulated Other Comprehensive Income (Loss) - Additional Information (Details) - USD ($)	22 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	May 31, 2018
Capital Structure And Accumulated Comprehensive Income (Loss)
Common stock authorized (shares)	500,000,000	500,000,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock issued (shares)	82,835,684	82,601,926
Common stock outstanding (shares)	73,757,495	73,601,950
Preferred stock authorized (shares)	10,000,000	10,000,000
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock issued (shares)	0	0
Preferred stock outstanding (shares)	0	0
May 2018 Share Repurchase Program
Capital Structure And Accumulated Comprehensive Income (Loss)
Share repurchase program authorized amount			$ 200,000,000
Repurchase of common stock (shares)	5,036,139
Average price per common share of repurchase common stock (in dollars per share)	$ 14.59
Remaining authorized repurchase amount	$ 126,500,000

Derivative Instruments - Effect of Derivatives Instruments on Combined Statements of Operations and Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Deferred Losses from Derivatives in OCI [Roll Forward]
Deferred losses from derivatives in OCI, beginning of period	$ (3,053)	$ (1,621)
Unrealized gain (loss) on derivatives	211	(940)
Deferred losses from derivatives in OCI, end of period	$ (2,842)	$ (2,561)

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Stockholders' Equity [Abstract]
Cash dividend declared per share (in dollars per share)	$ 0.02	$ 0.0625

Debt - Additional Information (Details)		1 Months Ended
Debt - Additional Information (Details)	May 01, 2018 USD ($)	Sep. 30, 2019	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Aug. 16, 2016 USD ($)
Revolving Line-of-Credit \| Revolver
Debt Instrument [Line Items]
Available borrowing base			$ 100,000,000.0
Amount drawn from borrowing base			25,000,000.0
Amount available under the credit facility without consent of lenders			68,500,000
Letter of Credit \| Revolver
Debt Instrument [Line Items]
Amount allocated for letters of credit			$ 6,500,000
Current consolidated leverage ratio			4.71
Current borrowing availability under the credit facility without consent of lenders			$ 30,000,000.0
Senior Secured Credit Facility \| Revolver
Debt Instrument [Line Items]
Net leverage ratio, credit facility threshold percentage	30.00%
Senior Secured Credit Facility \| Term Loan
Debt Instrument [Line Items]
Credit facility consolidated total net leverage ratio	0.0375
Senior Secured Credit Facility
Debt Instrument [Line Items]
Debt issued	$ 1,380,000,000
Senior Secured Credit Facility \| Term Loan
Debt Instrument [Line Items]
Debt issued	1,280,000,000
Senior Secured Credit Facility \| Revolving Line-of-Credit \| Revolver
Debt Instrument [Line Items]
Available borrowing base	100,000,000
Capitalized debt issuance costs	$ 38,700,000
Notes Payable \| Note payable secured by royalty interest
Debt Instrument [Line Items]
Annual minimum payments			500,000
Debt instrument, fair value			10,300,000		$ 22,500,000
Notes Payable \| Note payable secured by royalty interest \| Measurement Input, Discount Rate
Debt Instrument [Line Items]
Fair value discount rate					0.14
Notes Payable \| Insurance financing notes payable
Debt Instrument [Line Items]
Debt interest rate percentage		4.50%
Debt term		10 months
Notes payable balance			$ 1,998,000	$ 5,055,000

Commitments and Contingencies - Future Minimum Annual Commitments (Details) $ in Thousands	Mar. 31, 2020 USD ($)
Minimum Purchase Commitments
2020 (remaining nine months)	$ 10,327
2021	9,527
2022	7,075
2023	7,075
2024	3,767
Thereafter	2,490
Total future purchase commitments	$ 40,261

Organization and Basis of Presentation (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($) Segment	Mar. 31, 2019 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2019 USD ($)
Organization And Nature Of Business
Number of business segments \| Segment	2
Water rights intangibles acquired in VIE	$ 494	$ 1,307
Total assets of VIE	2,433,124			$ 2,553,234
Total liabilities of VIE	1,793,530			$ 1,836,654
Variable Interest Entity, Primary Beneficiary [Member]
Organization And Nature Of Business
Equity ownership percentage acquired in VIE			50.00%
Payments to acquire interest in VIE			$ 3,200
Maximum capital contribution in VIE			7,000
Additional capital contribution paid to acquire interest in VIE	100
Total assets of VIE	17,700
Total liabilities of VIE	$ 100
Variable Interest Entity, Primary Beneficiary [Member] \| Water rights
Organization And Nature Of Business
Water rights intangibles acquired in VIE			$ 700

Accounts Receivable

3 Months Ended

Mar. 31, 2020

Receivables [Abstract]

ACCOUNTS RECEIVABLE

NOTE F—ACCOUNTS RECEIVABLE

Accounts receivable are recorded when billed or accrued and represent claims against third parties that will be settled in cash. The carrying value of our accounts receivable, net of the allowance for credit losses, represents their estimated net realizable value. At March 31, 2020 and December 31, 2019, accounts receivable (in thousands) consisted of the following:



	March 31, 2020			December 31, 2019
Trade receivables	$	193,372		$	178,182
Less: Allowance for credit losses	(9,599		)	(8,984		)
Net trade receivables	183,773			169,198
Other receivables⁽¹⁾	49,082			13,040
Total accounts receivable	$	232,855		$	182,238



(1	)	At March 31, 2020, other receivables included $16.1 million of refundable alternative minimum tax credits and $28 million of refunds attributable to the CARES Act provision for net operating loss ("NOL") carrybacks from 2014-2019. At December 31, 2019, other receivables included $8.1 million of refundable alternative minimum tax credits.

We classify our trade receivables into the following portfolio segments: Oil & Gas Proppants and Industrial & Speciality Products, which also aligns with our reporting segments. We estimate the allowance for credit losses based on historical collection trends, the age of outstanding receivables, risks attributable to specific customers, such as credit history, bankruptcy or other going concern issues, and current economic and industry conditions. If events or circumstances indicate that specific receivable balances may be impaired, further consideration is given to the collectability of those balances and the allowance is adjusted accordingly. Past due balances are written off when we have exhausted our internal and external collection efforts and have been unsuccessful in collecting the amount due.

The following table is a rollforward of the allowance for credit losses (in thousands) for the three months ended March 31, 2020 disaggregated by portfolio segments:



	Oil & Gas Proppants		Industrial & Specialty Products			Total
Beginning balance, December 31, 2019	$	7,640	$	1,344		$	8,984
Provision for credit losses	840		62			902
Write-offs	—		(287		)	(287		)
Ending balance, March 31, 2020	$	8,480	$	1,119		$	9,599

Our ten largest customers accounted for approximately 38% and 42% of total sales for the three months ended March 31, 2020 and 2019, respectively. Sales to one of our customers accounted for 10% and 12% of our total sales for the three months ended March 31, 2020 and 2019, respectively. No other customers accounted for 10% or more of our total sales. At March 31, 2020, one of our customer's accounts receivable represented 10% of our total trade accounts receivable. At December 31, 2019, the same customer's accounts receivable represented 12% of our total trade accounts receivable. At March 31, 2020, one other customer's accounts receivable represented 10% of our total trade accounts receivable. No other customers accounted for 10% or more of our total trade accounts receivable.

Goodwill and Intangible Assets - Estimated Amortization Expense Related to Definite-Lived Intangible Assets (Details) $ in Thousands	Mar. 31, 2020 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2020 (remaining nine months)	$ 8,138
2021	10,848
2022	10,833
2023	10,828
2024	$ 10,830

Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Lessee, Lease, Description [Line Items]
Lease costs	$ 10,159	$ 26,284
Cost of sales
Lessee, Lease, Description [Line Items]
Lease costs	9,617	25,115
Short-term operating lease costs	2,800	6,600
Selling, general and administrative
Lessee, Lease, Description [Line Items]
Lease costs	542	1,169
Short-term operating lease costs	$ 100	$ 200

Revenue - Changes in Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Unbilled Receivables
Beginning Balance	$ 144	$ 90
Reclassifications to billed receivables	(144)	(90)
Revenues recognized in excess of period billings	108	1,641
Ending Balance	108	1,641
Deferred Revenue
Beginning Balance	50,634	113,319
Revenues recognized from balances held at the beginning of the period	(2,525)	(6,704)
Revenues deferred from period collections on unfulfilled performance obligations	0	10,025
Revenues recognized from period collections	0	(872)
Ending Balance	$ 48,109	$ 115,768

Pension and Post-Retirement Benefits - Additional Information (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($) plan	Mar. 31, 2019 USD ($)
Pension Plans, Postretirement and Other Employee Benefits
Number of multiemployer defined benefit plans \| plan	3
Percentage of contributions to individual multiemployer pension funds	5.00%	5.00%
Company contributions to qualified pension plans	$ 1.4	$ 1.3
Certain Employees
Pension Plans, Postretirement and Other Employee Benefits
Percentage of contribution over defined benefit plan	4.00%
All Other Eligible Employees
Pension Plans, Postretirement and Other Employee Benefits
Percentage of contribution over defined benefit plan based on eligible earnings (up to)	6.00%
Pension Plans
Pension Plans, Postretirement and Other Employee Benefits
Company's contributions to qualified plans	$ 0.7	$ 0.7
Expected contributions to the plans for next fiscal year	5.1
Post-retirement Medical Plan
Pension Plans, Postretirement and Other Employee Benefits
Expected contributions to the plans for next fiscal year	$ 1.4

Capital Structure and Accumulated Other Comprehensive Income (Loss) - Declared Quarterly Cash Dividends (Details)	Feb. 10, 2020 $ / shares
Equity [Abstract]
Dividends per Common Share (in dollars per share)	$ 0.02

Debt - Contractual Maturities of Note Payable Secured by Royalty Interest (Details) - Notes Payable - Note payable secured by royalty interest - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
2020 (remaining nine months)	$ 248
2021	380
2022	437
2023	502
2024	572
Thereafter	8,120
Total	$ 10,259	$ 10,438

Commitments and Contingencies

3 Months Ended

Mar. 31, 2020

Commitments and Contingencies Disclosure [Abstract]

COMMITMENTS AND CONTINGENCIES

NOTE O—COMMITMENTS AND CONTINGENCIES

Future Minimum Annual Commitments at March 31, 2020 (in thousands):



Year ending December 31,	Minimum Purchase Commitments
2020 (remaining nine months)	$	10,327
2021	9,527
2022	7,075
2023	7,075
2024	3,767
Thereafter	2,490
Total future purchase commitments	$	40,261

Minimum Purchase Commitments

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

Contingent Liability on Royalty Agreement

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

Other Commitments and Contingencies

Our operating subsidiary, U.S. Silica Company (“U.S. Silica”), has been named as a defendant in various product liability claims alleging silica exposure causing silicosis. During the three months ended March 31, 2020, zero new claims were brought against U.S. Silica. As of March 31, 2020, there were 55 active silica-related product liability claims pending in which U.S. Silica is a defendant. Although the outcomes of these claims cannot be predicted with certainty, in the opinion of management, it is not reasonably possible that the ultimate resolution of these matters will have a material adverse effect on our financial position or results of operations that exceeds the accrual amounts.

We have recorded estimated liabilities for these claims in other long-term liabilities 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 March 31, 2020 and December 31, 2019, other non-current assets included zero for insurance for third-party product liability claims. As of March 31, 2020 and December 31, 2019 other long-term liabilities included $1.0 million and $0.9 million, respectively, for third-party product liability claims.

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

Obligations under Guarantees

We have indemnified our insurers against any loss they may incur in the event that holders of surety bonds, issued on our behalf, execute the bonds. As of March 31, 2020, there was $36.3 million in bonds outstanding, of which $30.9 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 licenses, permits, and tax collection.

Pension and Post-Retirement Benefits (Tables)

3 Months Ended

Mar. 31, 2020

Retirement Benefits [Abstract]

Schedule of Net Pension and Post-Retirement Benefit Plans

Net pension benefit cost (in thousands) consisted of the following for the three months ended March 31, 2020 and 2019:



	Three Months Ended March 31,
	2020			2019
Service cost	$	653		$	586
Interest cost	989			2,584
Expected return on plan assets	(1,421		)	(3,184		)
Net amortization and deferral	894			624
Net pension benefit costs	$	1,115		$	610

Net post-retirement benefit cost (in thousands) consisted of the following for the three months ended March 31, 2020 and 2019:



	Three Months Ended March 31,
	2020		2019
Service cost	$	25	$	24
Interest cost	129		196
Net post-retirement benefit costs	$	154	$	220

Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Line of Credit Facility
Less: Unamortized original issue discount	$ (5,152)	$ (5,412)
Less: Unamortized debt issuance cost	(24,100)	(25,390)
Finance leases	38	70
Total debt	1,252,497	1,232,448
Less: current portion	(40,233)	(18,463)
Total long-term portion of debt	1,212,264	1,213,985
Notes Payable \| Insurance financing notes payable
Line of Credit Facility
Short-term debt	1,998	5,055
Notes Payable \| Note payable secured by royalty interest
Line of Credit Facility
Long-term debt	10,259	10,438
Notes Payable \| Equipment notes payable
Line of Credit Facility
Long-term debt	54	87
Revolving Line-of-Credit \| Revolver
Line of Credit Facility
Long-term debt	$ 25,000	$ 0
Credit facility, interest rate	6.25%	7.75%
Senior Secured Credit Facility \| Term Loan
Line of Credit Facility
Long-term debt	$ 1,244,400	$ 1,247,600
Credit facility, interest rate	5.00%	5.81%

Equity-Based Compensation

3 Months Ended

Mar. 31, 2020

Share-based Payment Arrangement [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 March 31, 2020, we have 673,336 shares of common stock that may be issued under the 2011 Plan. We use a combination of treasury stock and new shares if necessary to satisfy option exercises or vesting of restricted awards and performance share units.

Stock Options

The following table summarizes the status of, and changes in, our stock option awards during the three months ended March 31, 2020:



	Number of Shares	Weighted Average Exercise Price		Aggregate Intrinsic Value		Weighted Average Remaining Contractual Term in Years
Outstanding at December 31, 2019	826,658	$	28.97	$	11,557	4.1 years
Granted	—	$	—	$	—
Exercised	—	$	—	$	—
Forfeited	—	$	—	$	—
Expired	—	$	—	$	—
Outstanding at March 31, 2020	826,658	$	28.97	$	—	3.9 years
Exercisable at March 31, 2020	826,658	$	28.97	$	—	3.9 years

There were no grants of stock options during the three months ended March 31, 2020 and 2019.

There were 0 and 10,000 stock options exercised during the three months ended March 31, 2020 and 2019, respectively. The total intrinsic value of stock options exercised was $12 thousand for the three months ended March 31, 2019. Cash received from stock options exercised during the three months ended March 31, 2019 was $128 thousand. The tax benefit realized from stock option exercises was $3 thousand for the three months ended March 31, 2019.

As of March 31, 2020 and 2019, there was no unrecognized compensation expense related to these options. We account for forfeitures as they occur.

Restricted Stock and Restricted Stock Unit Awards

The following table summarizes the status of, and changes in, our unvested restricted stock awards during the three months ended March 31, 2020:



	Number of Shares		Grant Date Weighted Average Fair Value
Unvested, December 31, 2019	1,020,248		$	15.86
Granted	900,852		$	5.56
Vested	(245,004	)	$	13.96
Forfeited	(96,467	)	$	14.61
Unvested, March 31, 2020	1,579,629		$	10.35

We granted 900,852 restricted stock and restricted stock unit awards during the three months ended March 31, 2020. We granted 732,860 restricted stock and restricted stock unit awards during the three months ended March 31, 2019. The fair value of the awards was based on the market price of our stock at date of grant.

Our Board of Directors approved and amendment and restatement of the 2011 Plan, effective February 1, 2020, subject to shareholder approval at our 2020 annual meeting of shareholders (the "Annual Meeting"). The amendment increases the current share reserve by 4.025 million shares. During the three months ended March 31, 2020, we granted 834,677 restricted stock units to our executive employees, subject to stockholder approval of the amendment of the 2011 Plan at the Annual Meeting. If this proposal is not approved at the Annual Meeting, these awards will be settled in cash rather than equity.

We recognized $1.5 million of equity-based compensation expense related to restricted stock awards during the three months ended March 31, 2020. We recognized $2.3 million of equity-based compensation expense related to restricted stock awards during the three months ended March 31, 2019. As of March 31, 2020, there was $12.2 million of unrecognized compensation expense related to these restricted stock awards, which is expected to be recognized over a weighted-average period of 2.1 years.

We also granted 315,931 awards during the three months ended March 31, 2020. These awards will vest over a period of one to three years and will be settled in cash. As such, these awards have been classified as liability instruments. We recognized $39 thousand of expense related to these awards for the three months ended March 31, 2020. The liability for these

awards is included in accounts payable and other accrued expenses on our balance sheets. These awards will be remeasured at fair value each reporting period with resulting changes reflected in our income statements. Estimated unrecognized expense related to these awards is $0.5 million over a period of 2.9 years.

Performance Share Unit Awards

The following table summarizes the status of, and changes in, our performance share unit awards during the three months ended March 31, 2020:



	Number of Shares		Grant Date Weighted Average Fair Value
Unvested, December 31, 2019	838,722		$	18.00
Granted	1,020,161		$	9.94
Vested	—		$	—
Forfeited/Cancelled	(121,083	)	$	37.12
Unvested, March 31, 2020	1,737,800		$	13.90

We granted 1,020,161 performance share units during the three months ended March 31, 2020. We granted 607,130 performance share units during the three months ended March 31, 2019. The grant date fair value for these awards was estimated using a Monte Carlo simulation model. The Monte Carlo simulation model requires the use of highly subjective assumptions. Our key assumptions in the model included the price and the expected volatility of our common stock and our self-determined peer group companies’ stock, risk-free rate of interest, dividend yields and cross-correlations between our common stock and our self-determined peer group companies' stock.

We recognized $1.3 million of compensation expense related to performance share unit awards during the three months ended March 31, 2020. We recognized $1.7 million of compensation expense related to performance share unit awards during the three months ended March 31, 2019. As of March 31, 2020, there was $16.6 million of unrecognized compensation expense related to these performance share unit awards, which is expected to be recognized over a weighted-average period of 2.3 years.

We also granted 870,275 awards during the three months ended March 31, 2020. These awards will vest over a period of one to three years and will be settled in cash. As such, these awards have been classified as liability instruments. We recognized $0.7 million of expense related to these awards for the three months ended March 31, 2020. The liability for these awards is included in accounts payable and other accrued expenses on our balance sheets. These awards will be remeasured at fair value each reporting period with resulting changes reflected in our income statements. Estimated unrecognized expense related to these awards is $13.6 million over a period of 2.9 years.

Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Numerator:
Net loss attributable to U.S. Silica Holdings, Inc.	$ (72,345)	$ (19,324)
Denominator:
Weighted average shares outstanding (in shares)	73,467	73,040
Diluted effect of stock awards (shares)	0	0
Weighted average shares outstanding assuming dilution (shares)	73,467	73,040
Loss per share attributable to U.S. Silica Holdings, Inc.:
Basic loss per share (in dollars per share)	$ (0.98)	$ (0.26)
Diluted loss per share (in dollars per share)	$ (0.98)	$ (0.26)

- Definition

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

+ References

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+ Details

- Definition

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

+ References

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+ Details

- Definition

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

+ References + Details

Business Combinations (Details) - SandBox Logistics - Arrows Up, LLC	3 Months Ended
	Mar. 31, 2020 USD ($)
Business Acquisition [Line Items]
Consideration paid	$ 0
Fair value of assets acquired	19,900,000
Fair value of liabilities assumed	2,500,000
Gain recognized on bargain purchase	$ 17,400,000

Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
	Apr. 03, 2020	Mar. 31, 2020	Mar. 31, 2019
Subsequent Event
Cash dividend paid amount		$ 1,561	$ 4,610
Subsequent Event
Subsequent Event
Cash dividend paid amount	$ 1,500
Cash dividend paid per share (in dollars per share)	$ 0.02

Accounts Receivable (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Receivables [Abstract]
Trade receivables	$ 193,372	$ 178,182
Less: Allowance for credit losses	(9,599)	(8,984)
Net trade receivables	183,773	169,198
Other receivables	49,082	13,040
Total accounts receivable	232,855	182,238
Accounts, Notes, Loans and Financing Receivable [Line Items]
Refundable alternative minimum tax credits	16,100	$ 8,100
CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Refunds attributable to NOL carrybacks	$ 28,000

Revenue (Tables)

3 Months Ended

Mar. 31, 2020

Revenue from Contract with Customer [Abstract]

Schedule of Sales by Major Source

The following table disaggregates our sales by major source for the three months ended March 31, 2020 and 2019 (in thousands):



	Three Months Ended March 31, 2020						Three Months Ended March 31, 2019
Category	Oil & Gas Proppants		Industrial & Specialty Products		Total Sales		Oil & Gas Proppants		Industrial & Specialty Products		Total Sales
Product	$	108,277	$	113,884	$	222,161	$	178,587	$	118,273	$	296,860
Service	47,438		—		47,438		81,890		—		81,890
Total Sales	$	155,715	$	113,884	$	269,599	$	260,477	$	118,273	$	378,750

Schedule of Changes in Contract Assets and Liabilities

The following tables reflect the changes in our contract assets, which we classify as unbilled receivables and our contract liabilities, which we classify as deferred revenues, for the three months ended March 31, 2020 and 2019 (in thousands):



	Unbilled Receivables
	March 31, 2020			March 31, 2019
Beginning Balance	$	144		$	90
Reclassifications to billed receivables	(144		)	(90		)
Revenues recognized in excess of period billings	108			1,641
Ending Balance	$	108		$	1,641



	Deferred Revenue
	March 31, 2020			March 31, 2019
Beginning Balance	$	50,634		$	113,319
Revenues recognized from balances held at the beginning of the period	(2,525		)	(6,704		)
Revenues deferred from period collections on unfulfilled performance obligations	—			10,025
Revenues recognized from period collections	—			(872		)
Ending Balance	$	48,109		$	115,768

Schedule of Revenue Related to Foreign Operations

The following table includes information related to our foreign operations for the three months ended March 31, 2020 and 2019:



	March 31, 2020		March 31, 2019
Total Sales	$	21,605	$	15,300
Pre-tax income	$	4,213	$	900
Net income	$	3,328	$	800

Consolidated Assets	$	29,705	$	10,100

Schedule of Consolidated Assets Related to Foreign Operations

The following table includes information related to our foreign operations for the three months ended March 31, 2020 and 2019:



	March 31, 2020		March 31, 2019
Total Sales	$	21,605	$	15,300
Pre-tax income	$	4,213	$	900
Net income	$	3,328	$	800

Consolidated Assets	$	29,705	$	10,100

Goodwill and Intangible Assets - Carrying Amount of Goodwill by Business Segment (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($)
Goodwill [Roll Forward]
Balance at December, 2019	$ 273,524
Impairment loss	(86,100)
Balance at March 31, 2020	185,649
EPM
Goodwill [Roll Forward]
Impairment loss	(86,100)
EPM acquisition adjustment	(1,775)
Oil & Gas Proppants
Goodwill [Roll Forward]
Balance at December, 2019	86,100
Balance at March 31, 2020	0
Oil & Gas Proppants \| EPM
Goodwill [Roll Forward]
Impairment loss	(86,100)
EPM acquisition adjustment	0
Industrial & Specialty Products
Goodwill [Roll Forward]
Balance at December, 2019	187,424
Balance at March 31, 2020	185,649
Industrial & Specialty Products \| EPM
Goodwill [Roll Forward]
Impairment loss	0
EPM acquisition adjustment	$ (1,775)

Derivative Instruments - Additional Information (Details)	3 Months Ended
	Mar. 31, 2020 USD ($) derivative	Dec. 31, 2019 USD ($) derivative
Interest rate swap
Derivative [Line Items]
Ineffectiveness for derivative contracts	$ 0
Interest rate swap \| Cash Flow Hedges
Derivative [Line Items]
Number of derivative instruments held \| derivative	2	2
Interest rate swap - notional amount $440 million
Derivative [Line Items]
Fair value of derivatives liabilities	$ 2,576,000	$ 2,768,000
Interest rate swap - notional amount $440 million \| Cash Flow Hedges \| Other long-term liabilities
Derivative [Line Items]
Fair value of derivatives liabilities	2,600,000	2,800,000
Interest rate swap - notional amount $200 million
Derivative [Line Items]
Fair value of derivatives liabilities	1,172,000	1,259,000
Interest rate swap - notional amount $200 million \| Cash Flow Hedges \| Other long-term liabilities
Derivative [Line Items]
Fair value of derivatives liabilities	$ 1,200,000	$ 1,300,000

Goodwill and Intangible Assets

3 Months Ended

Mar. 31, 2020

Goodwill and Intangible Assets Disclosure [Abstract]

GOODWILL AND INTANGIBLE ASSETS

NOTE I—GOODWILL AND INTANGIBLE ASSETS

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



	Oil & Gas Proppants Segment			Industrial & Specialty Products Segment			Totals
Balance at December, 2019	$	86,100		$	187,424		$	273,524
Impairment loss	(86,100		)	—			(86,100		)
EPM acquisition adjustment⁽¹⁾	—			(1,775		)	(1,775		)
Balance at March 31, 2020	$	—		$	185,649		$	185,649

⁽¹⁾ Adjustment was made in accordance with ASC 250 to correct an immaterial error to acquisition accounting. We reclassified $1.8 million between goodwill and deferred tax liabilities. There was no impact to the Condensed Consolidated Statements of Operations.

Goodwill and trade names are evaluated for impairment annually as of October 31, or more frequently when indicators of impairment exist. We evaluated events and circumstances since the date of our last qualitative assessment, including macroeconomic conditions, industry and market conditions, and our overall financial performance.

During the first quarter of 2020, there was an unprecedented drop in global demand combined with the breakdown of the OPEC+ agreement to restrict oil production that led to one of the largest annual crude oil inventory builds in history. This led to sharp reductions in global crude oil prices. Containment measures and other economic, travel, and business disruptions caused by COVID-19 also affected refinery activity and future demand for crude oil, and consequently, the services and products of our Oil & Gas Proppants Segment. As a result of these triggering events, we performed a quantitative analysis and determined that the goodwill of our Oil & Gas reporting unit was impaired. We recognized goodwill impairment charges of $86.1 million, which were recorded in "Goodwill and other asset impairments" in the Condensed Consolidated Statements of Operations.

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



	March 31, 2020									December 31, 2019
	Gross Carrying Amount		Accumulated Amortization			Impairments		Net		Gross Carrying Amount		Accumulated Amortization			Impairments			Net

Technology and intellectual property	$	86,676	$	(18,591	)	$	—	$	68,085	$	86,183	$	(17,080	)	$	—		$	69,103
Customer relationships	66,999		(19,577		)	—		47,422		68,599		(18,737		)	(1,240		)	48,622
Total definite-lived intangible assets:	$	153,675	$	(38,168	)	$	—	$	115,507	$	154,782	$	(35,817	)	$	(1,240	)	$	117,725
Trade names	65,390		—			—		65,390		65,390		—			—			65,390
Other	700		—			—		700		700		—			—			700
Total intangible assets:	$	219,765	$	(38,168	)	$	—	$	181,597	$	220,872	$	(35,817	)	$	(1,240	)	$	183,815

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

Amortization expense was $2.7 million and $2.7 million for the three months ended March 31, 2020 and 2019, respectively.

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



2020 (remaining nine months)	$	8,138
2021	10,848
2022	10,833
2023	10,828
2024	10,830

Leases - Additional Information (Details)	3 Months Ended
Leases - Additional Information (Details)	Mar. 31, 2020
Minimum
Lessee, Lease, Description [Line Items]
Remaining term of lease contracts	1 year
Maximum
Lessee, Lease, Description [Line Items]
Remaining term of lease contracts	20 years

Segment Reporting (Tables)

3 Months Ended

Mar. 31, 2020

Segment Reporting [Abstract]

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

The following table presents sales and segment contribution margin (in thousands) for the reportable segments and other operating results not allocated to the reportable segments for the three months ended March 31, 2020 and 2019:



	Three Months Ended March 31,
	2020			2019
Sales:
Oil & Gas Proppants	$	155,715		$	260,477
Industrial & Specialty Products	113,884			118,273
Total sales	269,599			378,750
Segment contribution margin:
Oil & Gas Proppants	32,891			58,588
Industrial & Specialty Products	43,348			44,561
Total segment contribution margin	76,239			103,149
Operating activities excluded from segment cost of sales	(7,957		)	(21,937		)
Selling, general and administrative	(30,052		)	(34,656		)
Depreciation, depletion and amortization	(38,449		)	(44,600		)
Goodwill and other asset impairments	(103,866		)	—
Interest expense	(22,277		)	(23,978		)
Other income, net, including interest income	17,671			722
Income tax benefit (expense)	36,086			1,972
Net loss	$	(72,605	)	$	(19,328	)
Less: Net loss attributable to non-controlling interest	(260		)	(4		)
Net loss attributable to U.S. Silica Holdings, Inc.	$	(72,345	)	$	(19,324	)

Leases - Maturities of Lease Liabilities (Details) $ in Thousands	Mar. 31, 2020 USD ($)
Leases [Abstract]
2020 (remaining nine months)	$ 46,362
2021	45,227
2022	34,067
2023	22,411
2024	16,268
Thereafter	22,284
Total lease payments	186,619
Less: Interest	27,476
Total	$ 159,143

Segment Reporting - Sales and Segment Contribution Margin for Reporting Segments and Other Operating Results (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information
Total sales	$ 269,599	$ 378,750
Operating activities excluded from segment cost of sales	(7,957)	(21,937)
Selling, general and administrative	(30,052)	(34,656)
Depreciation, depletion and amortization	(38,449)	(44,600)
Goodwill and other asset impairments	(103,866)	0
Interest expense	(22,277)	(23,978)
Other income, net, including interest income	17,671	722
Income tax benefit	36,086	1,972
Net loss	(72,605)	(19,328)
Less: Net income (loss) attributable to non-controlling interest	(260)	(4)
Net loss attributable to U.S. Silica Holdings, Inc.	(72,345)	(19,324)
Operating Segments
Segment Reporting Information
Total sales	269,599	378,750
Total segment contribution margin	76,239	103,149
Oil & Gas Proppants
Segment Reporting Information
Total sales	155,715	260,477
Oil & Gas Proppants \| Operating Segments
Segment Reporting Information
Total sales	155,715	260,477
Total segment contribution margin	32,891	58,588
Industrial & Specialty Products
Segment Reporting Information
Total sales	113,884	118,273
Industrial & Specialty Products \| Operating Segments
Segment Reporting Information
Total sales	113,884	118,273
Total segment contribution margin	$ 43,348	$ 44,561

Capital Structure and Accumulated Other Comprehensive Income (Loss)

3 Months Ended

Mar. 31, 2020

Equity [Abstract]

CAPITAL STRUCTURE AND ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)

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

Common Stock

Our Amended and Restated Certificate of Incorporation authorizes up to 500,000,000 shares of common stock, par value of $0.01. Subject to the rights of holders of any series of preferred stock, all of the voting power of the stockholders of Holdings shall be vested in the holders of the common stock. There were 82,835,684 shares issued and 73,757,495 shares outstanding at March 31, 2020. There were 82,601,926 shares issued and 73,601,950 shares outstanding at December 31, 2019.

During the three months ended March 31, 2020, our Board of Directors declared quarterly cash dividends as follows:



Dividends per Common Share		Declaration Date	Record Date	Payable Date
$	0.02	February 10, 2020	March 13, 2020	April 3, 2020

All dividends were paid as scheduled.

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

Preferred Stock

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

There were no shares of preferred stock issued or outstanding at March 31, 2020 or December 31, 2019. At present, we have no plans to issue any preferred stock.

Share Repurchase Program

In May 2018, our Board of Directors authorized the repurchase of up to $200 million of our common stock from time to time on the open market or in privately negotiated transactions. Stock repurchases, if any, will be funded using our available liquidity. The timing and amount of stock repurchases will depend on a variety of factors, including the market conditions as well as corporate and regulatory considerations. As of March 31, 2020, we have repurchased a total of 5,036,139 shares of our common stock at an average price of $14.59 and have $126.5 million of remaining availability under this program.

Accumulated Other Comprehensive Loss

Accumulated other comprehensive loss consists of fair value adjustments associated with cash flow hedges, accumulated adjustments for net experience losses and prior service costs related to employee benefit plans and foreign currency translation adjustments, net of tax. The following table presents the changes in accumulated other comprehensive loss by component (in thousands) during the three months ended March 31, 2020:



	For the Three Months Ended March 31, 2020
	Unrealized gain on cash flow hedges			Foreign currency translation adjustments			Pension and other post-retirement benefits liability			Total
Beginning Balance	$	(3,053	)	$	(808	)	$	(15,993	)	$	(19,854	)
Other comprehensive loss before reclassifications	211			(289		)	(5,823		)	(5,901		)
Amounts reclassified from accumulated other comprehensive loss	—			—			695			695
Ending Balance	$	(2,842	)	$	(1,097	)	$	(21,121	)	$	(25,060	)

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

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
Income Taxes (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Mar. 31, 2019
Operating Loss Carryforwards [Line Items]
Estimated deferred tax benefit	$ 36,979	$ 2,553
Income tax benefit	$ 36,086	$ 1,972
Effective tax rate	33.00%	9.00%
Effective tax rate without the effects of discrete tax items	24.00%	29.00%
Tax expense related equity compensation	$ 500	$ 3,900
CARES Act
Operating Loss Carryforwards [Line Items]
Estimated deferred tax benefit	$ 11,200

Pension and Post-Retirement Benefits - Net Pension and Post-Retirement Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Pension Benefits
Pension Plans, Postretirement and Other Employee Benefits
Service cost	$ 653	$ 586
Interest cost	989	2,584
Expected return on plan assets	(1,421)	(3,184)
Net amortization and deferral	894	624
Net benefit costs	1,115	610
Post-retirement Benefits
Pension Plans, Postretirement and Other Employee Benefits
Service cost	25	24
Interest cost	129	196
Net benefit costs	$ 154	$ 220

Fair Value Accounting	3 Months Ended
Fair Value Accounting	Mar. 31, 2020
Fair Value Disclosures [Abstract]
FAIR VALUE ACCOUNTING	NOTE L—FAIR VALUE ACCOUNTING Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Fair value is estimated by applying the following hierarchy, which prioritizes the inputs used to measure fair value into three levels and bases the categorization within the hierarchy upon the lowest level of input that is available and significant to the fair value measurement: Level 1—Quoted prices in active markets for identical assets or liabilities. Level 2—Observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3—Inputs that are generally unobservable and typically reflect management’s estimate of assumptions that market participants would use in pricing the asset or liability. Cash Equivalents Due to the short-term maturity, we believe our cash equivalent instruments at March 31, 2020 and December 31, 2019, approximate their reported carrying values. Long-Term Debt, Including Current Maturities We believe that the fair values of our long-term debt, including current maturities, approximate their carrying values based on their effective interest rates compared to current market rates. Changes in the fair value of the royalty note payable utilize Level 3 inputs, such as estimates of future tonnages sold and average sales price. See Note J - Debt for more information on the royalty note payable. Derivative Instruments The estimated fair value of our derivative instruments are recorded at each reporting period and are based upon widely accepted valuation techniques, including discounted cash flow analysis on the expected cash flows of each derivative contract. This analysis reflects the contractual terms of the derivatives, including the period to maturity, and uses observable market-based inputs, including interest rate curves and implied volatilities. We also incorporate credit valuation adjustments to appropriately reflect both our nonperformance risk as well as that of the respective counterparty in the fair value measurements. Although we have determined that the majority of the inputs used to value our derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with our derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default of ourselves and our counterparties. However, as of March 31, 2020, we have assessed that the impact of the credit valuation adjustments on the overall valuation of our derivative positions is not significant. As a result, we have determined that our derivative valuations in their entirety are classified in Level 2 of the fair value hierarchy. See Note M - Derivative Instruments for more information.

- Definition

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

+ References + Details

Revenue - Additional Information (Details)	Mar. 31, 2020
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining duration period of expected satisfaction of performance obligations	1 year

Business Combinations	3 Months Ended
Business Combinations	Mar. 31, 2020
Business Combinations [Abstract]
BUSINESS COMBINATIONS	NOTE E—BUSINESS COMBINATIONS During the first quarter of 2020, we settled multiple intellectual property and contractual lawsuits involving our SandBox Logistics unit and Arrows Up, LLC. As part of the settlement, SandBox Logistics took control of Arrows Up's existing business, including all equipment and sand logistics contracts while also receiving a cash payment. We have accounted for the acquisition of Arrows Up, LLC under the acquisition method of accounting in accordance with ASC 805, Business Combinations. Estimates of fair value included in the Condensed Consolidated Financial Statements represent our best estimates and valuations. In accordance with the acquisition method of accounting, the fair values are subject to adjustment until we complete our analysis, within a period of time not to exceed one year after the date of acquisition, or March 7, 2021. This business combination resulted in a bargain purchase pursuant to ASC 805-30-25 because no consideration was paid for the fair value of assets acquired and liabilities assumed. The fair value of assets acquired, which included cash, accounts receivable, inventories, lease right-of-use assets, and property plant, and equipment, was $19.9 million. The fair value of liabilities assumed, which included lease liabilities and other long-term liabilities, was $2.5 million. A gain on bargain purchase of $17.4 million was recorded in "Other income, net, including interest income" in the Condensed Consolidated Statement of Operations.

Equity-Based Compensation - Restricted Stock and Restricted Stock Units Awards (Details) - Restricted Stock and Restricted Stock Units - $ / shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Number of Shares
Unvested, December 31, 2019 (in shares)	1,020,248
Granted (in shares)	900,852	732,860
Vested (in shares)	(245,004)
Forfeited (in shares)	(96,467)
Unvested, March 31, 2020 (in shares)	1,579,629
Grant Date Weighted Average Fair Value
Unvested, December 31, 2019 (in dollars per share)	$ 15.86
Granted (in dollars per share)	5.56
Vested (in dollars per share)	13.96
Forfeited (in dollars per share)	14.61
Unvested, March 31, 2020 (in dollars per share)	$ 10.35

Capital Structure and Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 639,594	$ 716,580	$ 1,034,098	$ 1,052,304
Ending Balance	628,495
Unrealized gain on cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(2,842)	(3,053)
Other comprehensive loss before reclassifications	211
Amounts reclassified from accumulated other comprehensive loss	0
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(1,097)	(808)
Other comprehensive loss before reclassifications	(289)
Amounts reclassified from accumulated other comprehensive loss	0
Pension and other post-retirement benefits liability
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(21,121)	(15,993)
Other comprehensive loss before reclassifications	(5,823)
Amounts reclassified from accumulated other comprehensive loss	695
Total
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(25,060)	$ (19,854)	$ (15,985)	$ (15,020)
Other comprehensive loss before reclassifications	(5,901)
Amounts reclassified from accumulated other comprehensive loss	$ 695

Debt (Tables)

3 Months Ended

Mar. 31, 2020

Debt Disclosure [Abstract]

Schedule of Debt

At March 31, 2020 and December 31, 2019, debt (in thousands) consisted of the following:



	March 31, 2020			December 31, 2019
Senior secured credit facility:
Revolver expiring May 1, 2023 (6.25% at March 31, 2020 and 7.75% at December 31, 2019)	$	25,000		$	—
Term Loan—final maturity May 1, 2025 (5.0% at March 31, 2020 and 5.81% at December 31, 2019)	1,244,400			1,247,600
Less: Unamortized original issue discount	(5,152		)	(5,412		)
Less: Unamortized debt issuance cost	(24,100		)	(25,390		)
Note payable secured by royalty interest	10,259			10,438
Insurance financing notes payable	1,998			5,055
Equipment notes payable	54			87
Finance leases	38			70
Total debt	1,252,497			1,232,448
Less: current portion	(40,233		)	(18,463		)
Total long-term portion of debt	$	1,212,264		$	1,213,985

Schedule of Contractual Maturities of Debt

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



2020 (remaining nine months)	$	248
2021	380
2022	437
2023	502
2024	572
Thereafter	8,120
Total	$	10,259

At March 31, 2020, contractual maturities of our Term Loan (in thousands) are as follows:



2020 (remaining nine months)	$	9,600
2021	12,800
2022	12,800
2023	12,800
2024	12,800
Thereafter	1,183,600
Total	$	1,244,400

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

3 Months Ended

Mar. 31, 2020

Equity [Abstract]

Schedule of Declared Quarterly Cash Dividends

During the three months ended March 31, 2020, our Board of Directors declared quarterly cash dividends as follows:



Dividends per Common Share		Declaration Date	Record Date	Payable Date
$	0.02	February 10, 2020	March 13, 2020	April 3, 2020

Schedule of Changes in Accumulated Other Comprehensive Income (Loss)

The following table presents the changes in accumulated other comprehensive loss by component (in thousands) during the three months ended March 31, 2020:



	For the Three Months Ended March 31, 2020
	Unrealized gain on cash flow hedges			Foreign currency translation adjustments			Pension and other post-retirement benefits liability			Total
Beginning Balance	$	(3,053	)	$	(808	)	$	(15,993	)	$	(19,854	)
Other comprehensive loss before reclassifications	211			(289		)	(5,823		)	(5,901		)
Amounts reclassified from accumulated other comprehensive loss	—			—			695			695
Ending Balance	$	(2,842	)	$	(1,097	)	$	(21,121	)	$	(25,060	)

Leases - Supplemental Balance Sheet Information (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease right-of-use assets	$ 48,847	$ 53,098
Current portion of operating lease liabilities	50,402	53,587
Non-current operating lease liabilities	108,741	117,964
Total lease liabilities	$ 159,143	$ 171,551
Operating leases, weighted average remaining lease term	4 years 4 months 24 days	4 years 6 months
Operating leases, weighted average discount rate	5.70%	5.70%

Derivative Instruments (Tables)

3 Months Ended

Mar. 31, 2020

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Estimated Fair Values of Derivative Instruments

The following table summarizes the fair value of our derivative instruments (in thousands, except contract/notional amount). See Note L - Fair Value Accounting for more information regarding the estimated fair values of our derivative instruments at March 31, 2020 and December 31, 2019.



	March 31, 2020										December 31, 2019
	Maturity Date	Contract/Notional Amount			Carrying Amount			Fair Value			Maturity Date	Contract/Notional Amount			Carrying Amount			Fair Value
LIBOR⁽¹⁾ interest rate swap agreement	2020		$440	million	$	(2,576	)	$	(2,576	)	2020		$440	million	$	(2,768	)	$	(2,768	)
LIBOR⁽¹⁾interest rate swap agreement	2020		$200	million	$	(1,172	)	$	(1,172	)	2020		$200	million	$	(1,259	)	$	(1,259	)

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

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

The following table summarizes the effect of derivative instruments (in thousands) on our income statements and our consolidated statements of comprehensive income for the three months ended March 31, 2020 and 2019:



	Three Months Ended March 31,
	2020			2019
Deferred losses from derivatives in OCI, beginning of period	$	(3,053	)	$	(1,621	)
Gain (loss) recognized in OCI from derivative instruments	211			(940		)
Deferred losses from derivatives in OCI, end of period	$	(2,842	)	$	(2,561	)

Cover Page - shares	3 Months Ended
Cover Page - shares	Mar. 31, 2020	Apr. 28, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2020
Document Transition Report	false
Entity File Number	001-35416
Entity Registrant Name	U.S. Silica Holdings, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	26-3718801
Entity Address, Address Line One	24275 Katy Freeway, Suite 600
Entity Address, City or Town	Katy
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77494
City Area Code	281
Local Phone Number	258-2170
Title of 12(b) Security	Common Stock, $0.01 par value
Trading Symbol	SLCA
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		73,807,128
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Entity Central Index Key	0001524741
Current Fiscal Year End Date	--12-31

Subsequent Events	3 Months Ended
Subsequent Events	Mar. 31, 2020
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	NOTE V— SUBSEQUENT EVENTS On April 3, 2020, we paid a cash dividend of $1.5 million or $0.02 per share to common stockholders of record as of the close of business on March 13, 2020, which had been declared by our Board of Directors on February 10, 2020.

Asset Retirement Obligations

3 Months Ended

Mar. 31, 2020

Asset Retirement Obligation Disclosure [Abstract]

ASSET RETIREMENT OBLIGATIONS

NOTE K—ASSET RETIREMENT OBLIGATIONS

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

As of March 31, 2020 and 2019, we had a liability of $25.3 million and $18.8 million, respectively, in other long-term liabilities related to our asset retirement obligations. Changes in the asset retirement obligations (in thousands) during the three months ended March 31, 2020 and 2019 are as follows:



	Three Months Ended March 31,
	2020			2019
Beginning balance	$	25,825		$	18,413
Accretion	373			373
Additions and revisions of estimates	(890		)	—
Ending balance	$	25,308		$	18,786

Equity-Based Compensation - Performance Share Awards (Details) - Performance Share Units - $ / shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Number of Shares
Unvested, December 31, 2019 (in shares)	838,722
Granted (in shares)	1,020,161	607,130
Vested (in shares)	0
Forfeited/Cancelled (in shares)	(121,083)
Unvested, March 31, 2020 (in shares)	1,737,800
Grant Date Weighted Average Fair Value
Unvested, December 31, 2019 (in dollars per share)	$ 18.00
Granted (in dollars per share)	9.94
Vested (in dollars per share)	0
Forfeited/Cancelled (in dollars per share)	37.12
Unvested, March 31, 2020 (in dollars per share)	$ 13.90

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock authorized (shares)	10,000,000	10,000,000
Preferred stock issued (shares)	0	0
Preferred stock outstanding (shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock authorized (shares)	500,000,000	500,000,000
Common stock issued (shares)	82,835,684	82,601,926
Common stock outstanding (shares)	73,757,495	73,601,950
Treasury stock, at cost (shares)	9,078,189	8,999,976

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Total U.S. Silica Holdings Inc., Stockholders’ Equity	Common Stock	Treasury Stock	Additional Paid-In Capital	Retained Deficit	Accumulated Other Comprehensive Loss	Non-controlling Interest
Beginning Balance at Dec. 31, 2018	$ 1,052,304	$ 1,044,820	$ 818	$ (178,215)	$ 1,169,383	$ 67,854	$ (15,020)	$ 7,484
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(19,328)	(19,324)				(19,324)		(4)
Unrealized gain (loss) on derivatives	(940)	(940)					(940)
Foreign currency translation adjustment	(199)	(199)					(199)
Pension and post-retirement liability	174	174					174
Cash dividend declared	(4,610)	(4,610)				(4,610)
Distributions to non-controlling interest	4,729							4,729
Common stock-based compensation plans activity:
Equity-based compensation	4,045	4,045			4,045
Proceeds from options exercised	128	128		295	(167)
Tax payments related to shares withheld for vested restricted stock and stock units	(2,205)	(2,205)	2	(2,205)	(2)
Ending Balance at Mar. 31, 2019	1,034,098	1,021,889	820	(180,125)	1,173,259	43,920	(15,985)	12,209
Beginning Balance at Dec. 31, 2019	716,580	705,217	823	(180,912)	1,185,116	(279,956)	(19,854)	11,363
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(72,605)	(72,345)				(72,345)		(260)
Unrealized gain (loss) on derivatives	211	211					211
Foreign currency translation adjustment	(289)	(289)					(289)
Pension and post-retirement liability	(5,128)	(5,128)					(5,128)
Cash dividend declared	(1,561)	(1,561)				(1,561)
Distributions to non-controlling interest	(4)							(4)
Common stock-based compensation plans activity:
Equity-based compensation	2,847	2,847			2,847
Tax payments related to shares withheld for vested restricted stock and stock units	(457)	(457)	1	(457)	(1)
Ending Balance at Mar. 31, 2020	$ 639,594	$ 628,495	$ 824	$ (181,369)	$ 1,187,962	$ (353,862)	$ (25,060)	$ 11,099

Goodwill and Intangible Assets (Tables)

3 Months Ended

Mar. 31, 2020

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Carrying Amount of Goodwill by Business Segment

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



	Oil & Gas Proppants Segment			Industrial & Specialty Products Segment			Totals
Balance at December, 2019	$	86,100		$	187,424		$	273,524
Impairment loss	(86,100		)	—			(86,100		)
EPM acquisition adjustment⁽¹⁾	—			(1,775		)	(1,775		)
Balance at March 31, 2020	$	—		$	185,649		$	185,649

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

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



	March 31, 2020									December 31, 2019
	Gross Carrying Amount		Accumulated Amortization			Impairments		Net		Gross Carrying Amount		Accumulated Amortization			Impairments			Net

Technology and intellectual property	$	86,676	$	(18,591	)	$	—	$	68,085	$	86,183	$	(17,080	)	$	—		$	69,103
Customer relationships	66,999		(19,577		)	—		47,422		68,599		(18,737		)	(1,240		)	48,622
Total definite-lived intangible assets:	$	153,675	$	(38,168	)	$	—	$	115,507	$	154,782	$	(35,817	)	$	(1,240	)	$	117,725
Trade names	65,390		—			—		65,390		65,390		—			—			65,390
Other	700		—			—		700		700		—			—			700
Total intangible assets:	$	219,765	$	(38,168	)	$	—	$	181,597	$	220,872	$	(35,817	)	$	(1,240	)	$	183,815

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

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



	March 31, 2020									December 31, 2019
	Gross Carrying Amount		Accumulated Amortization			Impairments		Net		Gross Carrying Amount		Accumulated Amortization			Impairments			Net

Technology and intellectual property	$	86,676	$	(18,591	)	$	—	$	68,085	$	86,183	$	(17,080	)	$	—		$	69,103
Customer relationships	66,999		(19,577		)	—		47,422		68,599		(18,737		)	(1,240		)	48,622
Total definite-lived intangible assets:	$	153,675	$	(38,168	)	$	—	$	115,507	$	154,782	$	(35,817	)	$	(1,240	)	$	117,725
Trade names	65,390		—			—		65,390		65,390		—			—			65,390
Other	700		—			—		700		700		—			—			700
Total intangible assets:	$	219,765	$	(38,168	)	$	—	$	181,597	$	220,872	$	(35,817	)	$	(1,240	)	$	183,815

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

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



2020 (remaining nine months)	$	8,138
2021	10,848
2022	10,833
2023	10,828
2024	10,830

Pension and Post-Retirement Benefits

3 Months Ended

Mar. 31, 2020

Retirement Benefits [Abstract]

PENSION AND POST-RETIREMENT BENEFITS

NOTE P—PENSION AND POST-RETIREMENT BENEFITS

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

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

Net pension benefit cost (in thousands) consisted of the following for the three months ended March 31, 2020 and 2019:



	Three Months Ended March 31,
	2020			2019
Service cost	$	653		$	586
Interest cost	989			2,584
Expected return on plan assets	(1,421		)	(3,184		)
Net amortization and deferral	894			624
Net pension benefit costs	$	1,115		$	610

Net post-retirement benefit cost (in thousands) consisted of the following for the three months ended March 31, 2020 and 2019:



	Three Months Ended March 31,
	2020		2019
Service cost	$	25	$	24
Interest cost	129		196
Net post-retirement benefit costs	$	154	$	220

We contributed $0.7 million to the qualified pension plans for both of the three months ended March 31, 2020 and 2019. Our best estimate of expected contributions to the pension and post-retirement medical benefit plans for the 2020 fiscal year are $5.1 million and $1.4 million, respectively.

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. Our contributions to individual multiemployer pension funds did not exceed 5% of the fund’s total contributions for the three months ended March 31, 2020 and 2019. Additionally, our contributions to multiemployer post-retirement benefit plans were immaterial for all periods presented in the accompanying condensed 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. For all other eligible employees, we make a contribution up to 6% of eligible earnings. Contributions were $1.4 million and $1.3 million for the three months ended March 31, 2020 and 2019, respectively.

Earnings Per Share (Tables)

3 Months Ended

Mar. 31, 2020

Earnings Per Share [Abstract]

Schedule of Computation of Basic and Diluted Earnings Per Share

The following table shows the computation of basic and diluted earnings per share for the three months ended March 31, 2020 and 2019:



In thousands, except per share amounts	Three Months Ended March 31,
	2020			2019
Numerator:
Net loss attributable to U.S. Silica Holdings, Inc.	$	(72,345	)	$	(19,324	)

Denominator:
Weighted average shares outstanding	73,467			73,040
Diluted effect of stock awards	—			—
Weighted average shares outstanding assuming dilution	73,467			73,040

Loss per share attributable to U.S. Silica Holdings, Inc.:
Basic loss per share	$	(0.98	)	$	(0.26	)
Diluted loss per share	$	(0.98	)	$	(0.26	)

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

Stock awards (in thousands) excluded from the calculation of diluted loss per common share were as follows:

Property, Plant and Mine Development

3 Months Ended

Mar. 31, 2020

Property, Plant and Equipment [Abstract]

PROPERTY, PLANT AND MINE DEVELOPMENT

NOTE H—PROPERTY, PLANT AND MINE DEVELOPMENT

At March 31, 2020 and December 31, 2019, property, plant and mine development (in thousands) consisted of the following:



	March 31, 2020			December 31, 2019
Mining property and mine development	$	788,574		$	794,899
Asset retirement cost	18,011			18,260
Land	57,494			57,082
Land improvements	74,027			73,203
Buildings	69,373			69,112
Machinery and equipment	1,177,350			1,152,898
Furniture and fixtures	4,071			4,068
Construction-in-progress	42,330			54,675
	2,231,230			2,224,197
Accumulated depletion, depreciation, amortization and impairment charges	(744,009		)	(706,610		)
Total property, plant and mine development, net	$	1,487,221		$	1,517,587

Depreciation, depletion, and amortization expense related to property, plant and mine development was $28.4 million and $34.2 million for the three months ended March 31, 2020 and 2019, respectively. At March 31, 2020 and December 31, 2019, the aggregate cost of machinery and equipment acquired under finance leases was $0.3 million and $0.3 million, respectively, reduced by accumulated depreciation of $0.2 million and $0.2 million, respectively. The amount of interest costs capitalized in property, plant and mine development was $33 thousand and $1.0 million for the three months ended March 31, 2020 and 2019, respectively.

During the first quarter of 2020, there was an unprecedented drop in global demand combined with the breakdown of the OPEC+ agreement to restrict oil production that led to one of the largest annual crude oil inventory builds in history. This led to sharp reductions in global crude oil prices. Containment measures and other economic, travel, and business disruptions caused by COVID-19 also affected refinery activity and future demand for crude oil, and consequently, the services and products of our Oil & Gas Proppants Segment. As a result of these events, we recorded impairment charges of $10.3 million related primarily to our Kosse, Texas facility, which has been idled. These impairment charges related to the Oil & Gas Proppants Segment and were recorded in "Goodwill and other asset impairments" in the Condensed Consolidated Statements of Operations.

On March 21, 2018, we completed the sale of three transload facilities located in the Permian, Eagle Ford, and Marcellus Basins to CIG Logistics (“CIG”) for total consideration of $86.1 million, including the assumption by CIG of $2.2 million of

Company obligations. Total cash consideration was $83.9 million. The consideration includes receipt of a vendor incentive from CIG to enter into master transloading service arrangements. Of the total consideration, $25.8 million was allocated to the fair value of the transload facilities, which had a net book value of $20.0 million and resulted in a gain on sale of $5.8 million. The consideration included a related asset retirement obligation of $2.1 million and an equipment note of $0.1 million assumed by CIG. In addition, $60.3 million of the consideration received in excess of the facilities' fair value was allocated to vendor incentives to be recognized as a reduction of costs using a service-level methodology over the contract lives of the transloading service arrangements. At March 31, 2020, vendor incentives of $21.1 million were classified in accounts payable and accrued expenses on our balance sheet.

Leases

3 Months Ended

Mar. 31, 2020

Leases [Abstract]

Leases

NOTE Q— LEASES

We lease railroad cars, office space, mining property, mining/processing equipment and transportation and other equipment. The majority of our leases have remaining lease terms of one year to 20 years. Our lease terms may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. As most of our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. We have lease agreements with lease and non-lease components, the latter of which are generally accounted for separately.

Supplemental balance sheet information related to leases was as follows:



Leases	Classification	March 31, 2020		December 31, 2019
Assets
Operating	Operating lease right-of-use assets	$	48,847	$	53,098
Total leased right-of-use assets		$	48,847	$	53,098
Liabilities
Current
Operating	Current portion of operating lease liabilities	$	50,402	$	53,587
Non-current
Operating	Operating lease liabilities	108,741		117,964
Total lease liabilities		$	159,143	$	171,551

Lease Term and Discount Rate
Weighted average remaining lease term:
Operating leases		4.4 years		4.5 years

Weighted average discount rate:
Operating leases		5.7%		5.7%

The components of lease expense were as follows:



Lease Costs	Classification	Three Months Ended March 31, 2020		Three Months Ended March 31, 2019
Operating lease costs⁽¹⁾	Cost of sales	$	9,617	$	25,115
Operating lease costs⁽²⁾	Selling, general and administrative	542		1,169
		$	10,159	$	26,284



(1) Includes short-term operating lease costs of $2.8 million and $6.6 million for the three months ended March 31, 2020 and 2019, respectively.
(2) Includes short-term operating lease costs of $0.1 million and $0.2 million for the three months ended March 31, 2020 and 2019, respectively.

Supplemental cash flow information related to leases was as follows:



	Three Months Ended March 31, 2020		Three Months Ended March 31, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows for operating leases	$	17,365	$	2,584

Right-of-use assets obtained in exchange for new lease liabilities:
Operating leases	$	3,872	$	223,027

Maturities of lease liabilities as of March 31, 2020:



Maturities of lease liabilities	Operating leases
2020 (remaining nine months)	$	46,362
2021	45,227
2022	34,067
2023	22,411
2024	16,268
Thereafter	22,284
Total lease payments	$	186,619
Less: Interest	27,476
Total	$	159,143

Leases

NOTE Q— LEASES

Supplemental balance sheet information related to leases was as follows:



Leases	Classification	March 31, 2020		December 31, 2019
Assets
Operating	Operating lease right-of-use assets	$	48,847	$	53,098
Total leased right-of-use assets		$	48,847	$	53,098
Liabilities
Current
Operating	Current portion of operating lease liabilities	$	50,402	$	53,587
Non-current
Operating	Operating lease liabilities	108,741		117,964
Total lease liabilities		$	159,143	$	171,551

Lease Term and Discount Rate
Weighted average remaining lease term:
Operating leases		4.4 years		4.5 years

Weighted average discount rate:
Operating leases		5.7%		5.7%

The components of lease expense were as follows:



Lease Costs	Classification	Three Months Ended March 31, 2020		Three Months Ended March 31, 2019
Operating lease costs⁽¹⁾	Cost of sales	$	9,617	$	25,115
Operating lease costs⁽²⁾	Selling, general and administrative	542		1,169
		$	10,159	$	26,284



(1) Includes short-term operating lease costs of $2.8 million and $6.6 million for the three months ended March 31, 2020 and 2019, respectively.
(2) Includes short-term operating lease costs of $0.1 million and $0.2 million for the three months ended March 31, 2020 and 2019, respectively.

Supplemental cash flow information related to leases was as follows:



	Three Months Ended March 31, 2020		Three Months Ended March 31, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows for operating leases	$	17,365	$	2,584

Right-of-use assets obtained in exchange for new lease liabilities:
Operating leases	$	3,872	$	223,027

Maturities of lease liabilities as of March 31, 2020:



Maturities of lease liabilities	Operating leases
2020 (remaining nine months)	$	46,362
2021	45,227
2022	34,067
2023	22,411
2024	16,268
Thereafter	22,284
Total lease payments	$	186,619
Less: Interest	27,476
Total	$	159,143

Inventories

3 Months Ended

Mar. 31, 2020

Inventory Disclosure [Abstract]

INVENTORIES

NOTE G—INVENTORIES

At March 31, 2020 and December 31, 2019, inventories (in thousands) consisted of the following:



	March 31, 2020		December 31, 2019
Supplies	$	48,300	$	47,277
Raw materials and work in process	36,519		41,167
Finished goods	34,265		35,988
Total inventories	$	119,084	$	124,432

During the first quarter of 2020, there was an unprecedented drop in global demand combined with the breakdown of the Organization of the Petroleum Exporting Countries and other oil producing nations ("OPEC+") agreement to restrict oil production that led to one of the largest annual crude oil inventory builds in history. This led to sharp reductions in global crude oil prices. Containment measures and other economic, travel, and business disruptions caused by the coronavirus disease of 2019 ("COVID-19") also affected refinery activity and future demand for crude oil, and consequently, the services and products of our Oil & Gas Proppants Segment. As a result of these events, we recorded impairment charges of $5.7 million primarily related to unused inventory at idled plants. These charges relate to the Oil & Gas Proppants Segment and were recorded in "Goodwill and other asset impairments" in the Condensed Consolidated Statements of Operations.

Derivative Instruments

3 Months Ended

Mar. 31, 2020

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 swap agreements in connection with our Term Loan to add stability to interest expense and to manage our exposure to interest rate movements. The derivative instruments are recorded on the balance sheet within other assets or liabilities at their fair values. As of March 31, 2020, the fair values of our two interest rate swaps were a liability of $2.6 million and a liability of $1.2 million and were classified within accounts payable and accrued liabilities on our balance sheets. At December 31, 2019, the fair values of our two interest rate swaps were a liability of $2.8 million and a liability of $1.3 million and were classified within accounts payable and accrued liabilities on our balance sheets. We have designated the interest rate swap agreements as qualified cash flow hedges. Accordingly, the effective portion of the gain or loss on the derivative instrument is reported as a component of other comprehensive income and recognized in earnings in the same period or periods during which the hedged transaction affects earnings.



	March 31, 2020										December 31, 2019
	Maturity Date	Contract/Notional Amount			Carrying Amount			Fair Value			Maturity Date	Contract/Notional Amount			Carrying Amount			Fair Value
LIBOR⁽¹⁾ interest rate swap agreement	2020		$440	million	$	(2,576	)	$	(2,576	)	2020		$440	million	$	(2,768	)	$	(2,768	)
LIBOR⁽¹⁾interest rate swap agreement	2020		$200	million	$	(1,172	)	$	(1,172	)	2020		$200	million	$	(1,259	)	$	(1,259	)

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

During the three months ended March 31, 2020, we had no ineffectiveness for the interest rate swap derivatives.



	Three Months Ended March 31,
	2020			2019
Deferred losses from derivatives in OCI, beginning of period	$	(3,053	)	$	(1,621	)
Gain (loss) recognized in OCI from derivative instruments	211			(940		)
Deferred losses from derivatives in OCI, end of period	$	(2,842	)	$	(2,561	)

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Sales:
Total sales	$ 269,599	$ 378,750
Cost of sales (excluding depreciation, depletion and amortization):
Total cost of sales (excluding depreciation, depletion and amortization)	201,317	297,538
Operating expenses:
Selling, general and administrative	30,052	34,656
Depreciation, depletion and amortization	38,449	44,600
Goodwill and other asset impairments	103,866	0
Total operating expenses	172,367	79,256
Operating (loss) income	(104,085)	1,956
Other (expense) income:
Interest expense	(22,277)	(23,978)
Other income, net, including interest income	17,671	722
Total other expense	(4,606)	(23,256)
Loss before income taxes	(108,691)	(21,300)
Income tax benefit	36,086	1,972
Net loss	(72,605)	(19,328)
Less: Net income (loss) attributable to non-controlling interest	(260)	(4)
Net loss attributable to U.S. Silica Holdings, Inc.	$ (72,345)	$ (19,324)
Loss per share attributable to U.S. Silica Holdings, Inc.:
Basic (in dollars per share)	$ (0.98)	$ (0.26)
Diluted (in dollars per share)	$ (0.98)	$ (0.26)
Weighted average shares outstanding:
Basic (shares)	73,467	73,040
Diluted (shares)	73,467	73,040
Dividends declared per share (in dollars per share)	$ 0.02	$ 0.0625
Product
Sales:
Total sales	$ 222,161	$ 296,860
Cost of sales (excluding depreciation, depletion and amortization):
Total cost of sales (excluding depreciation, depletion and amortization)	165,496	234,916
Service
Sales:
Total sales	47,438	81,890
Cost of sales (excluding depreciation, depletion and amortization):
Total cost of sales (excluding depreciation, depletion and amortization)	$ 35,821	$ 62,622

Accounts Receivable - Additional Information (Details) - Customer Concentration Risk	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Sales \| Ten Largest Customers
Concentration Risk [Line Items]
Concentration risk percentage	38.00%	42.00%
Sales \| Customer One
Concentration Risk [Line Items]
Concentration risk percentage	10.00%	12.00%
Trade Accounts Receivables \| Customer One
Concentration Risk [Line Items]
Concentration risk percentage	10.00%	12.00%

Equity-Based Compensation - Stock Options (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Number of Shares
Outstanding at December 31, 2019 (in shares)	826,658
Granted (in shares)	0	0
Exercised (in shares)	0	(10,000)
Forfeited (in shares)	0
Expired (in shares)	0
Outstanding at March 31, 2020 (in shares)	826,658		826,658
Exercisable at March 31, 2020 (in shares)	826,658
Weighted Average Exercise Price
Outstanding at December 31, 2019 (in dollars per share)	$ 28.97
Granted (in dollars per share)	0
Exercised (in dollars per share)	0
Forfeited (in dollars per share)	0
Expired (in dollars per share)	0
Outstanding at March 31, 2020 (in dollars per share)	28.97		$ 28.97
Exercisable at March 31, 2020 (in dollars per share)	$ 28.97
Aggregate Intrinsic Value
Outstanding	$ 0		$ 11,557
Exercisable at March 31, 2020	$ 0
Weighted Average Remaining Contractual Term in Years
Outstanding at March 31, 2020	3 years 10 months 24 days		4 years 1 month 6 days
Exercisable at March 31, 2020	3 years 10 months 24 days

Asset Retirement Obligations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Asset Retirement Obligation Disclosure [Abstract]
Other long-term liabilities related to asset retirement obligation	$ 25,300		$ 18,800
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance	25,825	$ 18,413
Accretion	373	373
Additions and revisions of estimates	(890)	0
Ending balance	$ 25,308	$ 18,786

Debt

3 Months Ended

Mar. 31, 2020

Debt Disclosure [Abstract]

DEBT

NOTE J—DEBT

At March 31, 2020 and December 31, 2019, debt (in thousands) consisted of the following:



	March 31, 2020			December 31, 2019
Senior secured credit facility:
Revolver expiring May 1, 2023 (6.25% at March 31, 2020 and 7.75% at December 31, 2019)	$	25,000		$	—
Term Loan—final maturity May 1, 2025 (5.0% at March 31, 2020 and 5.81% at December 31, 2019)	1,244,400			1,247,600
Less: Unamortized original issue discount	(5,152		)	(5,412		)
Less: Unamortized debt issuance cost	(24,100		)	(25,390		)
Note payable secured by royalty interest	10,259			10,438
Insurance financing notes payable	1,998			5,055
Equipment notes payable	54			87
Finance leases	38			70
Total debt	1,252,497			1,232,448
Less: current portion	(40,233		)	(18,463		)
Total long-term portion of debt	$	1,212,264		$	1,213,985

Senior Secured Credit Facility

On May 1, 2018, we entered into a Third Amended and Restated Credit Agreement (the "Credit Agreement"), which increased our existing senior debt by entering into a new $1.380 billion senior secured credit facility, consisting of a $1.280 billion term loan (the "Term Loan") and a $100 million revolving credit facility (the "Revolver") (collectively the "Credit

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

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

As of March 31, 2020 and December 31, 2019, we are in compliance with all covenants in accordance with our senior secured Credit Facility.

Term Loan

At March 31, 2020, contractual maturities of our Term Loan (in thousands) are as follows:



2020 (remaining nine months)	$	9,600
2021	12,800
2022	12,800
2023	12,800
2024	12,800
Thereafter	1,183,600
Total	$	1,244,400

Revolving Line-of-Credit

We have a $100.0 million Revolver with $25.0 million drawn and $6.5 million allocated for letters of credit as of March 31, 2020, leaving $68.5 million available under the Revolver. We have the intent and ability to repay the amounts outstanding on the Revolver within one year, therefore, the outstanding balance as of March 31, 2020 has been classified as current.

Based on our consolidated leverage ratio of 4.71:1.00 as of March 31, 2020, we may draw up to $30.0 million without the consent of our lenders. With the consent of our lenders, we have access to the full availability of the Revolver.

Note Payable Secured by Royalty Interest

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



2020 (remaining nine months)	$	248
2021	380
2022	437
2023	502
2024	572
Thereafter	8,120
Total	$	10,259

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

The royalty note payable fair value was estimated to be $22.5 million on the acquisition date. The estimate was made using a discounted cash flow model, which calculated the present value of projected future cash payments required under the agreement using a discounted rate of 14%, which is also the effective rate as of March 31, 2020. As of March 31, 2020, the note payable had a balance of $10.3 million. Changes in fair value of the note payable amount may result if estimates of future tonnages and sales increase or decrease.

Insurance Financing Notes Payable

During September 2019, the Company renewed its insurance policies and financed the payments through notes payable with a stated interest rate of 4.5%. These payments will be made in installments throughout a 10-month period and, as such, have been classified as current debt. As of March 31, 2020, the notes payable had a balance of $2.0 million.

Property, Plant and Mine Development (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment
Property, plant and mine development, gross	$ 2,231,230	$ 2,224,197
Accumulated depletion, depreciation, amortization and impairment charges	(744,009)	(706,610)
Total property, plant and mine development, net	1,487,221	1,517,587
Mining property and mine development
Property, Plant and Equipment
Property, plant and mine development, gross	788,574	794,899
Asset retirement cost
Property, Plant and Equipment
Property, plant and mine development, gross	18,011	18,260
Land
Property, Plant and Equipment
Property, plant and mine development, gross	57,494	57,082
Land improvements
Property, Plant and Equipment
Property, plant and mine development, gross	74,027	73,203
Buildings
Property, Plant and Equipment
Property, plant and mine development, gross	69,373	69,112
Machinery and equipment
Property, Plant and Equipment
Property, plant and mine development, gross	1,177,350	1,152,898
Furniture and fixtures
Property, Plant and Equipment
Property, plant and mine development, gross	4,071	4,068
Construction-in-progress
Property, Plant and Equipment
Property, plant and mine development, gross	$ 42,330	$ 54,675

Revenue

3 Months Ended

Mar. 31, 2020

Revenue from Contract with Customer [Abstract]

REVENUE

NOTE S— REVENUE

We consider sales disaggregated at the product and service level by business segment to depict how the nature, amount, timing and uncertainty of revenues and cash flow are impacted by changes in economic factors. The following table disaggregates our sales by major source for the three months ended March 31, 2020 and 2019 (in thousands):



	Three Months Ended March 31, 2020						Three Months Ended March 31, 2019
Category	Oil & Gas Proppants		Industrial & Specialty Products		Total Sales		Oil & Gas Proppants		Industrial & Specialty Products		Total Sales
Product	$	108,277	$	113,884	$	222,161	$	178,587	$	118,273	$	296,860
Service	47,438		—		47,438		81,890		—		81,890
Total Sales	$	155,715	$	113,884	$	269,599	$	260,477	$	118,273	$	378,750



	Unbilled Receivables
	March 31, 2020			March 31, 2019
Beginning Balance	$	144		$	90
Reclassifications to billed receivables	(144		)	(90		)
Revenues recognized in excess of period billings	108			1,641
Ending Balance	$	108		$	1,641



	Deferred Revenue
	March 31, 2020			March 31, 2019
Beginning Balance	$	50,634		$	113,319
Revenues recognized from balances held at the beginning of the period	(2,525		)	(6,704		)
Revenues deferred from period collections on unfulfilled performance obligations	—			10,025
Revenues recognized from period collections	—			(872		)
Ending Balance	$	48,109		$	115,768

We have elected to use the practical expedients allowed under ASC 606-10-50-14, pursuant to which we have excluded disclosures of transaction prices allocated to remaining performance obligations and when we expect to recognize such revenue. The majority of our remaining performance obligations are primarily comprised of unfulfilled product, transportation service, and labor service orders, all of which hold a remaining duration of less than one year. The long-term portion of deferred revenue primarily represents a combination of refundable and nonrefundable customer prepayments for which related current performance obligations do not yet exist, but are expected to arise, before the expiration of the contract. Our

residual unfulfilled performance obligations are comprised primarily of long-term equipment rental arrangements in which we recognize revenues equal to what we have a right to invoice. Generally, no variable consideration exists related to our remaining performance obligations and no consideration is excluded from the associated transaction prices.

Foreign Operations

The following table includes information related to our foreign operations for the three months ended March 31, 2020 and 2019:



	March 31, 2020		March 31, 2019
Total Sales	$	21,605	$	15,300
Pre-tax income	$	4,213	$	900
Net income	$	3,328	$	800

Consolidated Assets	$	29,705	$	10,100

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating activities:
Net loss	$ (72,605)	$ (19,328)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation, depletion and amortization	38,449	44,600
Goodwill and other asset impairments	103,866	0
Debt issuance amortization	860	1,322
Original issue discount amortization	690	265
Deferred income taxes	(36,979)	(2,553)
Deferred revenue	(2,525)	(7,576)
(Gain) loss on disposal of property, plant and equipment	(419)	113
Equity-based compensation	2,847	4,045
Provision for credit losses, net of recoveries	902	721
Other	(16,792)	(3,872)
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable	(13,471)	(43,583)
Inventories	2,917	18,938
Prepaid expenses and other current assets	(4,820)	3,151
Income taxes	578	812
Accounts payable and accrued expenses	(40,455)	12,970
Liability for pension and other post-retirement benefits	6,751	924
Other noncurrent assets and liabilities	(10,597)	(48)
Net cash (used in) provided by operating activities	(40,803)	10,901
Investing activities:
Capital expenditures	(16,116)	(44,376)
Capitalized intellectual property costs	(494)	(1,307)
Proceeds from sale of property, plant and equipment	224	0
Net cash used in investing activities	(16,386)	(45,683)
Financing activities:
Dividends paid	(4,604)	(4,690)
Proceeds from options exercised	0	128
Tax payments related to shares withheld for vested restricted stock and stock units	(457)	(2,205)
Proceeds from draw down of the Revolver	25,000	0
Payments on long-term debt	(3,782)	(4,043)
(Distributions to) contributions from non-controlling interest	(4)	4,729
Principal payments on finance lease obligations	(3)	(20)
Net cash provided by (used in) financing activities	16,150	(6,101)
Net decrease in cash and cash equivalents	(41,039)	(40,883)
Cash and cash equivalents, beginning of period	185,740	202,498
Cash and cash equivalents, end of period	144,701	161,615
Cash paid during the period for:
Interest	20,677	21,557
Taxes, net of refunds	101	(472)
Non-cash items:
Accrued capital expenditures	20,111	39,239
Net assets assumed in business acquisition	$ 10,955	$ 0

Summary of Significant Accounting Policies	3 Months Ended
Summary of Significant Accounting Policies	Mar. 31, 2020
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	NOTE B—SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Use of Estimates and Assumptions The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the related disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. The more significant areas requiring the use of management estimates and assumptions relate to the purchase price allocation for businesses acquired; mineral reserves that are the basis for future cash flow estimates utilized in impairment calculations and units-of-production amortization calculations; environmental, reclamation and closure obligations; estimates of recoverable minerals; estimates of allowance for doubtful accounts; estimates of fair value for certain reporting units and asset impairments (including impairments of goodwill, intangible assets and other long-lived assets); write-downs of inventory to net realizable value; equity-based compensation expense; post-employment, post-retirement and other employee benefit liabilities; valuation allowances for deferred tax assets; contingent considerations; reserves for contingencies and litigation and the fair value and accounting treatment of financial instruments, including derivative instruments. We base our estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances. Accordingly, actual results may differ significantly from these estimates under different assumptions or conditions. New Accounting Pronouncements Recently Adopted In August 2018, the FASB issued ASU 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. The new guidance requires a customer in a cloud computing arrangement (i.e., hosting arrangement) that is a service contract to follow the internal-use software guidance in ASC 350-40 to determine which implementation costs to capitalize as assets or expense as incurred. Capitalized implementation costs related to a hosting arrangement that is a service contract will be amortized over the term of the hosting arrangement, beginning when the module or component of the hosting arrangement is ready for its intended use. The update is effective for calendar-year public business entities in 2020. We adopted the new standard on January 1, 2020. The adoption of this ASU had no significant impact on our Condensed Consolidated Statements of Operations. In November 2018, FASB issued ASU 2018-19, Codification Improvements to Topic 326, Financial Instruments-Credit Losses. The amendments in this ASU clarified issues related to Topic 326. In Issue 1, the amendment in this ASU mitigates transition complexity by requiring that for nonpublic business entities the amendments in ASU 2016-13 are effective for fiscal years after December 15, 2021, including interim periods within those fiscal years. In Issue 2, the amendment clarifies that receivables arising from operating leases are not within the scope of Subtopic 326-20. Impairment of receivables arising from operating leases should be accounted for in accordance with Topic 842, Leases. The ASU is effective for all entities for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. We adopted the new standard on January 1, 2020. The adoption of the new standard did not have a significant impact on our Condensed Consolidated Financial Statements as our current process for estimating expected credit losses for trade receivables aligns with the expected credit loss model. See Note F - Accounts Receivable for more information. New Accounting Pronouncements Not Yet Adopted In August 2018, the FASB issued ASU 2018-14, Compensation - Retirement Benefits - Defined Benefit Plans - General (Subtopic 715-20). The new guidance removes certain disclosure requirements for employers which sponsor defined benefit pension or other post-retirement plans, but also adds disclosure requirements for the weighted average interest crediting rates for cash balance plans and other plans with promised crediting rates and an explanation of the reasons for significant gains and losses related to changes in the benefit obligation for the period. The amendments also clarify disclosure requirements for the projected benefit obligation (PBO) and accumulated benefit obligation (ABO) and fair value of plan assets for plans with PBOs and ABOs in excess of plan assets. Entities should apply the amendments on a retrospective basis for all periods presented. The amendments in this ASU are effective for public entities for fiscal years ending after December 15, 2020. We are currently evaluating the effect that the guidance will have on our disclosures. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. The amendments in this ASU simplify the accounting for income taxes by removing several exceptions and also simplify the accounting for income taxes by requiring that an entity recognize a franchise tax (or similar tax) that is partially based on income as an income-based tax and account for any incremental amount incurred as a non-income-based tax, requiring that an entity evaluate when a step up in the tax basis of goodwill should be considered part of the business combination in which the book goodwill was originally recognized and when it should be considered a separate transaction, specifying that an entity is not required to allocate the consolidated amount of current and deferred tax expense to a legal entity that is not subject to tax in its separate financial statements (however, an entity may elect to do so on an entity-by-entity basis) for a legal entity that is both not subject to tax and disregarded by the taxing authority, requiring that an entity reflect the effect of an enacted change in tax laws or rates in the annual effective tax rate computation in the interim period that includes the enactment date, and making minor codification improvements for income taxes related to employee stock ownership plans and investments in qualified affordable housing projects accounted for using the equity method. For public business entities, the amendments in this Update are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. We are currently evaluating the effect that the guidance will have on our financial statements and related disclosures.

Inventories (Details) - USD ($) $ in Thousands	3 Months Ended
Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Supplies	$ 48,300	$ 47,277
Raw materials and work in process	36,519	41,167
Finished goods	34,265	35,988
Total inventories	119,084	$ 124,432
Impairment changes related to unused inventory at idled plants	$ 5,700

Segment Reporting - Additional Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($) Segment Product	Dec. 31, 2019 USD ($)
Segment Reporting Information
Number of reportable segments \| Segment	2
Number of product types (over 400) \| Product	400
Goodwill	$ 185,649	$ 273,524
Operating Segments \| Oil & Gas Proppants
Segment Reporting Information
Goodwill	0	86,100
Operating Segments \| Industrial & Specialty Products
Segment Reporting Information
Goodwill	$ 185,600	$ 187,400

Leases (Tables)

3 Months Ended

Mar. 31, 2020

Leases [Abstract]

Schedule of Supplemental Balance Sheet Information

Supplemental balance sheet information related to leases was as follows:



Leases	Classification	March 31, 2020		December 31, 2019
Assets
Operating	Operating lease right-of-use assets	$	48,847	$	53,098
Total leased right-of-use assets		$	48,847	$	53,098
Liabilities
Current
Operating	Current portion of operating lease liabilities	$	50,402	$	53,587
Non-current
Operating	Operating lease liabilities	108,741		117,964
Total lease liabilities		$	159,143	$	171,551

Lease Term and Discount Rate
Weighted average remaining lease term:
Operating leases		4.4 years		4.5 years

Weighted average discount rate:
Operating leases		5.7%		5.7%

Schedule of Components of Lease Expense and Supplemental Cash Flow Information

The components of lease expense were as follows:



Lease Costs	Classification	Three Months Ended March 31, 2020		Three Months Ended March 31, 2019
Operating lease costs⁽¹⁾	Cost of sales	$	9,617	$	25,115
Operating lease costs⁽²⁾	Selling, general and administrative	542		1,169
		$	10,159	$	26,284



(1) Includes short-term operating lease costs of $2.8 million and $6.6 million for the three months ended March 31, 2020 and 2019, respectively.
(2) Includes short-term operating lease costs of $0.1 million and $0.2 million for the three months ended March 31, 2020 and 2019, respectively.

Supplemental cash flow information related to leases was as follows:



	Three Months Ended March 31, 2020		Three Months Ended March 31, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows for operating leases	$	17,365	$	2,584

Right-of-use assets obtained in exchange for new lease liabilities:
Operating leases	$	3,872	$	223,027

Schedule of Maturity of Lease Liabilities

Maturities of lease liabilities as of March 31, 2020:



Maturities of lease liabilities	Operating leases
2020 (remaining nine months)	$	46,362
2021	45,227
2022	34,067
2023	22,411
2024	16,268
Thereafter	22,284
Total lease payments	$	186,619
Less: Interest	27,476
Total	$	159,143

Related Party Transactions	3 Months Ended
Related Party Transactions	Mar. 31, 2020
Related Party Transactions [Abstract]
RELATED PARTY TRANSACTIONS	NOTE T— RELATED PARTY TRANSACTIONS There were no related party transactions during the three months ended March 31, 2020 or 2019.

Accounts Receivable - Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Allowance for Doubtful Accounts Receivable Roll Forward
Beginning balance, December 31, 2019	$ 8,984
Provision for credit losses	902	$ 721
Write-offs	(287)
Ending balance, March 31, 2020	9,599
Oil & Gas Proppants
Allowance for Doubtful Accounts Receivable Roll Forward
Beginning balance, December 31, 2019	7,640
Provision for credit losses	840
Write-offs	0
Ending balance, March 31, 2020	8,480
Industrial & Specialty Products
Allowance for Doubtful Accounts Receivable Roll Forward
Beginning balance, December 31, 2019	1,344
Provision for credit losses	62
Write-offs	(287)
Ending balance, March 31, 2020	$ 1,119

Income Taxes	3 Months Ended
Income Taxes	Mar. 31, 2020
Income Tax Disclosure [Abstract]
INCOME TAXES	NOTE R— INCOME TAXES For interim period reporting, we record income taxes using an estimated annual effective tax rate based upon projected annual income, forecasted permanent tax differences, discrete items and statutory rates in states in which we operate. At the end of each interim period, we update the estimated annual effective tax rate, and if the estimated tax rate changes based on new information, we make a cumulative adjustment in the period. We record the tax effect of an unusual or infrequently occurring item in the interim period in which it occurs as a discrete item of tax. On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (“CARES” Act) was enacted and signed into law in response to the COVID-19 pandemic. Certain provisions of the CARES Act impact our 2019 income tax provision computations and are reflected in the first quarter of 2020, or the period of enactment. The CARES Act, among other things, permits NOL carryovers and carrybacks to offset 100% of taxable income for taxable years beginning after 2017 and before 2021. In addition, the CARES Act allows NOLs generated after 2017 and before 2021 to be carried back to each of the five preceding taxable years to generate a refund of previously paid income taxes. We intend to carry the NOL generated in 2019 back to offset a portion of the taxable income in the 2014 tax year. The deferred tax asset related to the NOL generated in 2019 was recorded at the statutory income tax rate for 2019 of 21%. As a result of the carry back of this NOL to 2014, the NOL will be utilized at the statutory income tax rate for 2014 of 35%. This increase in the tax rate at which the 2019 NOL will be utilized results in a deferred tax benefit. Accordingly, during the three months ended March 31, 2020, we recorded an estimated deferred tax benefit of $11.2 million. Pursuant to ASC 740, this has been recorded as a discrete component of the tax benefit. The CARES Act also accelerates the ability of companies to receive refunds of alternative minimum tax (“AMT”) credits related to tax years beginning in 2018 and 2019. AMT credits have been presented as a receivable or a deferred tax asset in the prior period balance sheets. The presentation of refundable AMT credits in the current balance sheet have been reclassified from deferred tax asset to accounts receivable to reflect the timing of when the credits are expected to be monetized. Additionally, the CARES Act provides temporary relief for payment of certain payroll taxes. Prior to the CARES Act, payroll taxes generally would have been deductible for income tax purposes in the same period that they were expensed for book purposes under the “recurring item exception” of the Internal Revenue Code. However, if a company defers payment of its payroll taxes as a result of the CARES Act such that the recurring item exception no longer applies, accrued payroll taxes would not be deductible until the tax year in which they are actually paid. If the book expense and tax deduction are expected to occur in different periods, a deferred tax asset would need to be recorded for the deductible temporary difference related to the payroll tax accrual. The temporary relief for payment of certain payroll taxes will not have an impact to the first quarter of 2020. We are currently still evaluating all provisions of the CARES Act and its impact on income tax and in our Consolidated Statements of Operation. For the three months ended March 31, 2020 and 2019, we had tax benefits of $36.1 million and $2.0 million, respectively. The effective tax rate was 33% and 9% for the three months ended March 31, 2020 and 2019, respectively. Without discrete items, which primarily consist of tax expense related to equity compensation and a tax benefit related to the carryback of the 2019 NOL to 2014, the effective tax rate for the three months ended March 31, 2020 and 2019 would have been 24% and 29%, respectively. During the three months ended March 31, 2020 and 2019, we recorded tax expense related to equity compensation of $0.5 million and $3.9 million, respectively.

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Tax expense (benefit) on unrealized (loss) gain on derivatives	$ 67	$ (299)
Tax expense (benefit) on foreign currency translation adjustment	(92)	(60)
Tax (expense) benefit on pension and other post-retirement benefits liability adjustment	$ (1,634)	$ 55

Asset Retirement Obligations (Tables)

3 Months Ended

Mar. 31, 2020

Asset Retirement Obligation Disclosure [Abstract]

Schedule of Changes in Asset Retirement Obligations

Changes in the asset retirement obligations (in thousands) during the three months ended March 31, 2020 and 2019 are as follows:



	Three Months Ended March 31,
	2020			2019
Beginning balance	$	25,825		$	18,413
Accretion	373			373
Additions and revisions of estimates	(890		)	—
Ending balance	$	25,308		$	18,786

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation	The accompanying unaudited Condensed Consolidated Financial Statements for the quarter ended March 31, 2020 included in this Quarterly Report on Form 10-Q have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X issued by the U.S. Securities and Exchange Commission (“SEC”). They do not contain certain information included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2019; therefore, the unaudited Condensed Consolidated Financial Statements should be read in conjunction with that Annual Report on Form 10-K. Operating results for the three–month period ended March 31, 2020 are not necessarily indicative of the results that may be expected for the full year ending December 31, 2020. In the opinion of management, all adjustments necessary for a fair presentation have been included. Such adjustments are of a normal, recurring nature.
Consolidation	The unaudited Condensed Consolidated Financial Statements include the accounts of Holdings and its direct and indirect wholly-owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. We follow Financial Accounting Standards Board ("FASB") Accounting Standards Codification (“ASC”) guidance for identification and reporting of entities over which control is achieved through means other than voting rights. The guidance defines such entities as Variable Interest Entities (“VIEs”). We consolidate VIEs when we have variable interests and are the primary beneficiary. We continually evaluate our involvement with VIEs to determine when these criteria are met.
Use of Estimates and Assumptions	Use of Estimates and Assumptions The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the related disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. The more significant areas requiring the use of management estimates and assumptions relate to the purchase price allocation for businesses acquired; mineral reserves that are the basis for future cash flow estimates utilized in impairment calculations and units-of-production amortization calculations; environmental, reclamation and closure obligations; estimates of recoverable minerals; estimates of allowance for doubtful accounts; estimates of fair value for certain reporting units and asset impairments (including impairments of goodwill, intangible assets and other long-lived assets); write-downs of inventory to net realizable value; equity-based compensation expense; post-employment, post-retirement and other employee benefit liabilities; valuation allowances for deferred tax assets; contingent considerations; reserves for contingencies and litigation and the fair value and accounting treatment of financial instruments, including derivative instruments. We base our estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances. Accordingly, actual results may differ significantly from these estimates under different assumptions or conditions.
New Accounting Pronouncements Recently Adopted and New Accounting Pronouncements Not Yet Adopted	New Accounting Pronouncements Recently Adopted In August 2018, the FASB issued ASU 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. The new guidance requires a customer in a cloud computing arrangement (i.e., hosting arrangement) that is a service contract to follow the internal-use software guidance in ASC 350-40 to determine which implementation costs to capitalize as assets or expense as incurred. Capitalized implementation costs related to a hosting arrangement that is a service contract will be amortized over the term of the hosting arrangement, beginning when the module or component of the hosting arrangement is ready for its intended use. The update is effective for calendar-year public business entities in 2020. We adopted the new standard on January 1, 2020. The adoption of this ASU had no significant impact on our Condensed Consolidated Statements of Operations. In November 2018, FASB issued ASU 2018-19, Codification Improvements to Topic 326, Financial Instruments-Credit Losses. The amendments in this ASU clarified issues related to Topic 326. In Issue 1, the amendment in this ASU mitigates transition complexity by requiring that for nonpublic business entities the amendments in ASU 2016-13 are effective for fiscal years after December 15, 2021, including interim periods within those fiscal years. In Issue 2, the amendment clarifies that receivables arising from operating leases are not within the scope of Subtopic 326-20. Impairment of receivables arising from operating leases should be accounted for in accordance with Topic 842, Leases. The ASU is effective for all entities for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. We adopted the new standard on January 1, 2020. The adoption of the new standard did not have a significant impact on our Condensed Consolidated Financial Statements as our current process for estimating expected credit losses for trade receivables aligns with the expected credit loss model. See Note F - Accounts Receivable for more information. New Accounting Pronouncements Not Yet Adopted In August 2018, the FASB issued ASU 2018-14, Compensation - Retirement Benefits - Defined Benefit Plans - General (Subtopic 715-20). The new guidance removes certain disclosure requirements for employers which sponsor defined benefit pension or other post-retirement plans, but also adds disclosure requirements for the weighted average interest crediting rates for cash balance plans and other plans with promised crediting rates and an explanation of the reasons for significant gains and losses related to changes in the benefit obligation for the period. The amendments also clarify disclosure requirements for the projected benefit obligation (PBO) and accumulated benefit obligation (ABO) and fair value of plan assets for plans with PBOs and ABOs in excess of plan assets. Entities should apply the amendments on a retrospective basis for all periods presented. The amendments in this ASU are effective for public entities for fiscal years ending after December 15, 2020. We are currently evaluating the effect that the guidance will have on our disclosures. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. The amendments in this ASU simplify the accounting for income taxes by removing several exceptions and also simplify the accounting for income taxes by requiring that an entity recognize a franchise tax (or similar tax) that is partially based on income as an income-based tax and account for any incremental amount incurred as a non-income-based tax, requiring that an entity evaluate when a step up in the tax basis of goodwill should be considered part of the business combination in which the book goodwill was originally recognized and when it should be considered a separate transaction, specifying that an entity is not required to allocate the consolidated amount of current and deferred tax expense to a legal entity that is not subject to tax in its separate financial statements (however, an entity may elect to do so on an entity-by-entity basis) for a legal entity that is both not subject to tax and disregarded by the taxing authority, requiring that an entity reflect the effect of an enacted change in tax laws or rates in the annual effective tax rate computation in the interim period that includes the enactment date, and making minor codification improvements for income taxes related to employee stock ownership plans and investments in qualified affordable housing projects accounted for using the equity method. For public business entities, the amendments in this Update are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. We are currently evaluating the effect that the guidance will have on our financial statements and related disclosures.
Fair Value Measurement	Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Fair value is estimated by applying the following hierarchy, which prioritizes the inputs used to measure fair value into three levels and bases the categorization within the hierarchy upon the lowest level of input that is available and significant to the fair value measurement: Level 1—Quoted prices in active markets for identical assets or liabilities. Level 2—Observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3—Inputs that are generally unobservable and typically reflect management’s estimate of assumptions that market participants would use in pricing the asset or liability. Cash Equivalents Due to the short-term maturity, we believe our cash equivalent instruments at March 31, 2020 and December 31, 2019, approximate their reported carrying values. Long-Term Debt, Including Current Maturities We believe that the fair values of our long-term debt, including current maturities, approximate their carrying values based on their effective interest rates compared to current market rates. Changes in the fair value of the royalty note payable utilize Level 3 inputs, such as estimates of future tonnages sold and average sales price. See Note J - Debt for more information on the royalty note payable. Derivative Instruments The estimated fair value of our derivative instruments are recorded at each reporting period and are based upon widely accepted valuation techniques, including discounted cash flow analysis on the expected cash flows of each derivative contract. This analysis reflects the contractual terms of the derivatives, including the period to maturity, and uses observable market-based inputs, including interest rate curves and implied volatilities. We also incorporate credit valuation adjustments to appropriately reflect both our nonperformance risk as well as that of the respective counterparty in the fair value measurements. Although we have determined that the majority of the inputs used to value our derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with our derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default of ourselves and our counterparties. However, as of March 31, 2020, 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.

Leases - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Leases [Abstract]
Cash paid for amounts included in the measurement of lease liabilities, operating leases	$ 17,365	$ 2,584
Right-of-use assets obtained in exchange for new lease liabilities, operating leases	$ 3,872	$ 223,027

Equity-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2020

Share-based Payment Arrangement [Abstract]

Schedule of Stock Options Activity

The following table summarizes the status of, and changes in, our stock option awards during the three months ended March 31, 2020:



	Number of Shares	Weighted Average Exercise Price		Aggregate Intrinsic Value		Weighted Average Remaining Contractual Term in Years
Outstanding at December 31, 2019	826,658	$	28.97	$	11,557	4.1 years
Granted	—	$	—	$	—
Exercised	—	$	—	$	—
Forfeited	—	$	—	$	—
Expired	—	$	—	$	—
Outstanding at March 31, 2020	826,658	$	28.97	$	—	3.9 years
Exercisable at March 31, 2020	826,658	$	28.97	$	—	3.9 years

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

The following table summarizes the status of, and changes in, our unvested restricted stock awards during the three months ended March 31, 2020:



	Number of Shares		Grant Date Weighted Average Fair Value
Unvested, December 31, 2019	1,020,248		$	15.86
Granted	900,852		$	5.56
Vested	(245,004	)	$	13.96
Forfeited	(96,467	)	$	14.61
Unvested, March 31, 2020	1,579,629		$	10.35

The following table summarizes the status of, and changes in, our performance share unit awards during the three months ended March 31, 2020:



	Number of Shares		Grant Date Weighted Average Fair Value
Unvested, December 31, 2019	838,722		$	18.00
Granted	1,020,161		$	9.94
Vested	—		$	—
Forfeited/Cancelled	(121,083	)	$	37.12
Unvested, March 31, 2020	1,737,800		$	13.90

Commitments and Contingencies - Additional Information (Details)		3 Months Ended
	May 17, 2017 USD ($)	Mar. 31, 2020 USD ($) claim	Dec. 31, 2019 USD ($)
Loss Contingencies
Purchased reserves	$ 94,400,000
Number of new claims \| claim		0
Surety Bonds
Loss Contingencies
Surety bonds outstanding		$ 36,300,000
Reclamation Bonds
Loss Contingencies
Surety bonds outstanding		30,900,000
Other non-current assets
Loss Contingencies
Third party products claims liability under insurance in other long-term obligations		0	$ 0
Other long-term obligations
Loss Contingencies
Third party products claims liability under insurance in other long-term obligations		$ 1,000,000.0	$ 900,000
Pending Litigation
Loss Contingencies
Number of pending claims \| claim		55

Goodwill and Intangible Assets - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment	$ 86.1
Amortization expense	$ 2.7	$ 2.7
Technology and intellectual property
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives of intangibles	15 years
Customer relationships \| Minimum
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives of intangibles	13 years
Customer relationships \| Maximum
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives of intangibles	15 years

Inventories (Tables)

3 Months Ended

Mar. 31, 2020

Inventory Disclosure [Abstract]

Schedule of Inventories

At March 31, 2020 and December 31, 2019, inventories (in thousands) consisted of the following:



	March 31, 2020		December 31, 2019
Supplies	$	48,300	$	47,277
Raw materials and work in process	36,519		41,167
Finished goods	34,265		35,988
Total inventories	$	119,084	$	124,432

Earnings Per Share - Antidilutive Securities Excluded From Calculation of Diluted Earnings Per Share (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average outstanding stock options and restricted stock awards excluded (shares)	41	171
Stock options excluded
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average outstanding stock options and restricted stock awards excluded (shares)	827	736
Restricted stock and performance share units awards excluded
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average outstanding stock options and restricted stock awards excluded (shares)	2,391	353

Property, Plant and Mine Development - Additional Information (Details) $ in Thousands		3 Months Ended
	Mar. 21, 2018 USD ($) transload	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)
Property, Plant and Equipment
Depreciation expense		$ 28,400	$ 34,200
Impairment of property, plant and equipment		10,300
Gain on sale of transload facilities		419	(113)
Permian, Eagle Ford, and Appalachian Basins \| Disposal Group, Disposed of by Sale, Not Discontinued Operations \| CIG Logistics
Property, Plant and Equipment
Number of transload facilities sold \| transload	3
Total consideration received on sale of transload facilities	$ 86,100
Liabilities assumed by buyer on sale of transload facilities	2,200
Cash consideration received on sale of transload facilities	83,900
Gain on sale of transload facilities	5,800
Consideration received allocated to asset retirement obligations liabilities of transload facilities	2,100
Equipment note assumed the buyer on sale of transload facilities	100
Consideration allocated to vendor incentives in sale of transload facilities	60,300
Permian, Eagle Ford, and Appalachian Basins \| Disposal Group, Disposed of by Sale, Not Discontinued Operations \| CIG Logistics \| Accounts payables and accrued liabilities
Property, Plant and Equipment
Consideration allocated to vendor incentives in sale of transload facilities		21,100
Machinery and equipment
Property, Plant and Equipment
Aggregate cost of assets acquired under finance leases		300		$ 300
Accumulated amortization of assets acquired under finance leases		200		$ 200
Mining property and mine development
Property, Plant and Equipment
Interest cost capitalized in property, plant and mine development		$ 33	$ 1,000
Transload Facilities \| Permian, Eagle Ford, and Appalachian Basins \| Disposal Group, Disposed of by Sale, Not Discontinued Operations \| CIG Logistics
Property, Plant and Equipment
Consideration received allocated to fair value of transload facilities	25,800
Net book value of transload facilities	$ 20,000

Organization and Basis of Presentation	3 Months Ended
Organization and Basis of Presentation	Mar. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
ORGANIZATION AND BASIS OF PRESENTATION	NOTE A—ORGANIZATION AND BASIS OF PRESENTATION Organization U.S. Silica Holdings, Inc. (“Holdings,” and together with its subsidiaries “we,” “us” or the “Company”) is a performance materials company and one of the largest domestic producers of commercial silica used in the oil and gas industry and in a wide range of industrial applications. In addition, through our acquisition of EP Minerals, LLC ("EPM") and its affiliated companies in 2018, we are an industry leader in the production of industrial minerals, including diatomaceous earth, clay (calcium bentonite and calcium montmorillonite) and perlite. During our 120-year history, we have developed core competencies in mining, processing, logistics and materials science that enable us to produce and cost-effectively deliver products to customers across our end markets. Our operations are organized into two reportable segments based on end markets served: (1) Oil & Gas Proppants and (2) Industrial & Specialty Products. See Note U - Segment Reporting for more information on our reportable segments. Basis of Presentation and Consolidation The accompanying unaudited Condensed Consolidated Financial Statements for the quarter ended March 31, 2020 included in this Quarterly Report on Form 10-Q have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X issued by the U.S. Securities and Exchange Commission (“SEC”). They do not contain certain information included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2019; therefore, the unaudited Condensed Consolidated Financial Statements should be read in conjunction with that Annual Report on Form 10-K. Operating results for the three–month period ended March 31, 2020 are not necessarily indicative of the results that may be expected for the full year ending December 31, 2020. In the opinion of management, all adjustments necessary for a fair presentation have been included. Such adjustments are of a normal, recurring nature. The unaudited Condensed Consolidated Financial Statements include the accounts of Holdings and its direct and indirect wholly-owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. We follow Financial Accounting Standards Board ("FASB") Accounting Standards Codification (“ASC”) guidance for identification and reporting of entities over which control is achieved through means other than voting rights. The guidance defines such entities as Variable Interest Entities (“VIEs”). We consolidate VIEs when we have variable interests and are the primary beneficiary. We continually evaluate our involvement with VIEs to determine when these criteria are met. During the third quarter of 2018 we finalized a shareholders' agreement with unrelated parties to form a limited liability company with the purpose of constructing and operating a water pipeline to transport and sell water. In connection with the shareholders’ agreement, we acquired a 50% equity ownership in the limited liability company for $3.2 million, with a maximum initial capital contribution of $7.0 million, and a water rights intangible asset for $0.7 million. Based on our evaluation, we determined that this limited liability company is a VIE of which we are the primary beneficiary and therefore we are required to consolidate it. As of March 31, 2020, the VIE had total assets of $17.7 million and total liabilities of $0.1 million. We made $0.1 million in capital contributions during the three months ended March 31, 2020. Throughout this report we refer to (i) our unaudited Condensed Consolidated Balance Sheets as our “Balance Sheets,” (ii) our unaudited Condensed Consolidated Statements of Operations as our “Income Statements,” and (iii) our unaudited Condensed Consolidated Statements of Cash Flows as our “Cash Flows.”

Property, Plant and Mine Development (Tables)

3 Months Ended

Mar. 31, 2020

Property, Plant and Equipment [Abstract]

Schedule of Property, Plant and Mine Development

At March 31, 2020 and December 31, 2019, property, plant and mine development (in thousands) consisted of the following:



	March 31, 2020			December 31, 2019
Mining property and mine development	$	788,574		$	794,899
Asset retirement cost	18,011			18,260
Land	57,494			57,082
Land improvements	74,027			73,203
Buildings	69,373			69,112
Machinery and equipment	1,177,350			1,152,898
Furniture and fixtures	4,071			4,068
Construction-in-progress	42,330			54,675
	2,231,230			2,224,197
Accumulated depletion, depreciation, amortization and impairment charges	(744,009		)	(706,610		)
Total property, plant and mine development, net	$	1,487,221		$	1,517,587

Debt - Contractual Maturities of Senior Secured Credit Facility (Details) - Senior Secured Credit Facility - Term Loan - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
2020 (remaining nine months)	$ 9,600
2021	12,800
2022	12,800
2023	12,800
2024	12,800
Thereafter	1,183,600
Total	$ 1,244,400	$ 1,247,600

Goodwill and Intangible Assets - Carrying Amount of Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 153,675	$ 154,782
Accumulated Amortization	(38,168)	(35,817)
Impairments	0	(1,240)
Net	115,507	117,725
Total Intangible Assets
Gross Carrying Amount	219,765	220,872
Accumulated Amortization	(38,168)	(35,817)
Impairments	0	(1,240)
Net	181,597	183,815
Trade names
Indefinite-lived Intangible Assets
Gross Carrying Amount	65,390	65,390
Impairments	0	0
Other
Indefinite-lived Intangible Assets
Gross Carrying Amount	700	700
Impairments	0	0
Technology and intellectual property
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	86,676	86,183
Accumulated Amortization	(18,591)	(17,080)
Impairments	0	0
Net	68,085	69,103
Total Intangible Assets
Accumulated Amortization	(18,591)	(17,080)
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	66,999	68,599
Accumulated Amortization	(19,577)	(18,737)
Impairments	0	(1,240)
Net	47,422	48,622
Total Intangible Assets
Accumulated Amortization	$ (19,577)	$ (18,737)

Segment Reporting

3 Months Ended

Mar. 31, 2020

Segment Reporting [Abstract]

SEGMENT REPORTING

NOTE U— SEGMENT REPORTING

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

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

The Industrial & Specialty Products segment consists of over 400 product types and materials used in a variety of industries, including container glass, fiberglass, specialty glass, flat glass, building products, fillers and extenders, foundry products, chemicals, recreation products and filtration products.

An operating segment’s performance is primarily evaluated based on segment contribution margin, which excludes selling, general, and administrative costs, corporate costs, plant capacity expansion expenses, and facility closure costs. We believe that segment contribution margin, as defined above, is an appropriate measure for evaluating the operating performance of our segments. However, segment contribution margin is a non-GAAP measure and should be considered in addition to, not a substitute for, or superior to, net income (loss) or other measures of financial performance prepared in accordance with GAAP. The other accounting policies of each of the two reportable segments are the same as those in Note B - Summary of Significant Accounting Policies to the Consolidated Financial Statements in Item 8 of our 2019 Annual Report on Form 10-K.



	Three Months Ended March 31,
	2020			2019
Sales:
Oil & Gas Proppants	$	155,715		$	260,477
Industrial & Specialty Products	113,884			118,273
Total sales	269,599			378,750
Segment contribution margin:
Oil & Gas Proppants	32,891			58,588
Industrial & Specialty Products	43,348			44,561
Total segment contribution margin	76,239			103,149
Operating activities excluded from segment cost of sales	(7,957		)	(21,937		)
Selling, general and administrative	(30,052		)	(34,656		)
Depreciation, depletion and amortization	(38,449		)	(44,600		)
Goodwill and other asset impairments	(103,866		)	—
Interest expense	(22,277		)	(23,978		)
Other income, net, including interest income	17,671			722
Income tax benefit (expense)	36,086			1,972
Net loss	$	(72,605	)	$	(19,328	)
Less: Net loss attributable to non-controlling interest	(260		)	(4		)
Net loss attributable to U.S. Silica Holdings, Inc.	$	(72,345	)	$	(19,324	)

Asset information, including capital expenditures and depreciation, depletion, and amortization, by segment is not included in reports used by management in its monitoring of performance and, therefore, is not reported by segment. At March 31, 2020, goodwill of $185.6 million has been allocated to these segments with zero assigned to Oil & Gas Proppants and $185.6 million to Industrial & Specialty Products. At December 31, 2019, goodwill of $273.5 million had been allocated to these segments with $86.1 million assigned to Oil & Gas Proppants and $187.4 million to Industrial & Specialty Products.

Earnings Per Share

3 Months Ended

Mar. 31, 2020

Earnings Per Share [Abstract]

EARNINGS PER SHARE

NOTE C—EARNINGS PER SHARE

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

Diluted net earnings per share assumes the conversion of contingently convertible securities and stock options under the treasury stock method, if dilutive. Contingently convertible securities and stock options are excluded from the calculation of fully diluted earnings per share if they are anti-dilutive, including when we incur a loss from continuing operations.

The following table shows the computation of basic and diluted earnings per share for the three months ended March 31, 2020 and 2019:



In thousands, except per share amounts	Three Months Ended March 31,
	2020			2019
Numerator:
Net loss attributable to U.S. Silica Holdings, Inc.	$	(72,345	)	$	(19,324	)

Denominator:
Weighted average shares outstanding	73,467			73,040
Diluted effect of stock awards	—			—
Weighted average shares outstanding assuming dilution	73,467			73,040

Loss per share attributable to U.S. Silica Holdings, Inc.:
Basic loss per share	$	(0.98	)	$	(0.26	)
Diluted loss per share	$	(0.98	)	$	(0.26	)

Potentially dilutive shares (in thousands) of 41 and 171 for the three months ended March 31, 2020 and 2019, respectively, were excluded from the calculation of diluted weighted average shares outstanding and diluted earnings per share because we were in a net loss position. Certain stock options, restricted stock awards and performance share units were excluded from the computation of diluted earnings per share because their effect would have been anti-dilutive. Stock awards (in thousands) excluded from the calculation of diluted loss per common share were as follows:

Commitments and Contingencies (Tables)

3 Months Ended

Mar. 31, 2020

Commitments and Contingencies Disclosure [Abstract]

Schedule of Future Minimum Annual Commitments

Future Minimum Annual Commitments at March 31, 2020 (in thousands):



Year ending December 31,	Minimum Purchase Commitments
2020 (remaining nine months)	$	10,327
2021	9,527
2022	7,075
2023	7,075
2024	3,767
Thereafter	2,490
Total future purchase commitments	$	40,261

Revenue - Foreign Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Total sales	$ 269,599	$ 378,750
Pre-tax income	(108,691)	(21,300)
Net income	(72,345)	(19,324)
Consolidated Assets	2,433,124		$ 2,553,234
Foreign Operations
Disaggregation of Revenue [Line Items]
Total sales	21,605	15,300
Pre-tax income	4,213	900
Net income	3,328	800
Consolidated Assets	$ 29,705	$ 10,100

- Definition

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

+ References + Details

Equity-Based Compensation - Additional Information (Details) - USD ($)		3 Months Ended
	Feb. 01, 2020	Mar. 31, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants of stock options (in shares)		0	0
Stock options exercised (in shares)		0	10,000
Intrinsic value of stock options exercised			$ 12,000
Cash received from options exercised		$ 0	128,000
Tax benefit realized for deductions from stock options exercises			3,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense related to stock options		$ 0	$ 0
Restricted Stock and Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)		900,852	732,860
Restricted Stock Units \| Executive Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)		834,677
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized equity-based compensation		$ 1,500,000	$ 2,300,000
Unrecognized compensation expense related to awards		$ 12,200,000
Recognized weighted-average period		2 years 1 month 6 days
Restricted Stock and Restricted Stock Units to be Settled in Cash
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)		315,931
Recognized equity-based compensation		$ 39,000
Unrecognized compensation expense related to awards		$ 500,000
Recognized weighted-average period		2 years 10 months 24 days
Restricted Stock and Restricted Stock Units to be Settled in Cash \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		1 year
Restricted Stock and Restricted Stock Units to be Settled in Cash \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		3 years
Performance Share Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)		1,020,161	607,130
Recognized equity-based compensation		$ 1,300,000	$ 1,700,000
Unrecognized compensation expense related to awards		$ 16,600,000
Recognized weighted-average period		2 years 3 months 18 days
Performance Shares to be Settled in Cash
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)		870,275
Recognized equity-based compensation		$ 700,000
Unrecognized compensation expense related to awards		$ 13,600,000
Recognized weighted-average period		2 years 10 months 24 days
Performance Shares to be Settled in Cash \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		1 year
Performance Shares to be Settled in Cash \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		3 years
2011 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock that may be issued (in shares)		673,336
Increase in number of shares reserved	4,025,000.000

Revenue - Sales by Major Source (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Total Sales	$ 269,599	$ 378,750
Oil & Gas Proppants
Disaggregation of Revenue [Line Items]
Total Sales	155,715	260,477
Industrial & Specialty Products
Disaggregation of Revenue [Line Items]
Total Sales	113,884	118,273
Product
Disaggregation of Revenue [Line Items]
Total Sales	222,161	296,860
Product \| Oil & Gas Proppants
Disaggregation of Revenue [Line Items]
Total Sales	108,277	178,587
Product \| Industrial & Specialty Products
Disaggregation of Revenue [Line Items]
Total Sales	113,884	118,273
Service
Disaggregation of Revenue [Line Items]
Total Sales	47,438	81,890
Service \| Oil & Gas Proppants
Disaggregation of Revenue [Line Items]
Total Sales	47,438	81,890
Service \| Industrial & Specialty Products
Disaggregation of Revenue [Line Items]
Total Sales	$ 0	$ 0

Derivative Instruments - Estimated Fair Values of Derivative Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Interest rate swap - notional amount $440 million
Derivative Instruments, Gain (Loss)
Contract/Notional Amount	$ 440,000	$ 440,000
Carrying Amount	(2,576)	(2,768)
Fair Value	$ (2,576)	$ (2,768)
Interest rate swap - notional amount $440 million \| LIBOR
Derivative Instruments, Gain (Loss)
Derivative, basis spread on variable rate (maximum)	2.74%	2.74%
Interest rate swap - notional amount $200 million
Derivative Instruments, Gain (Loss)
Contract/Notional Amount	$ 200,000	$ 200,000
Carrying Amount	(1,172)	(1,259)
Fair Value	$ (1,172)	$ (1,259)
Interest rate swap - notional amount $200 million \| LIBOR
Derivative Instruments, Gain (Loss)
Derivative, basis spread on variable rate (maximum)	2.74%	2.74%