U.S. Silica (SLCA) 10-Q29 Oct 202020 Q3 Quarterly reportFinancial data

Company Profile

Cover Page

Cover Page - shares	9 Months Ended
Cover Page - shares	Sep. 30, 2020	Oct. 28, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 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		73,949,978
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Entity Central Index Key	0001524741
Current Fiscal Year End Date	--12-31

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current Assets:
Cash and cash equivalents	$ 134,923	$ 185,740
Accounts receivable, net	173,827	182,238
Inventories, net	104,711	124,432
Prepaid expenses and other current assets	44,280	16,155
Income tax deposits	0	475
Total current assets	457,741	509,040
Property, plant and mine development, net	1,415,636	1,517,587
Operating lease right-of-use assets	41,265	53,098
Goodwill	185,649	273,524
Intangible assets, net	164,632	183,815
Other assets	11,724	16,170
Total assets	2,276,647	2,553,234
Current Liabilities:
Accounts payable and accrued expenses	128,193	248,237
Current portion of operating lease liabilities	30,887	53,587
Current portion of long-term debt	44,248	18,463
Current portion of deferred revenue	15,531	15,111
Total current liabilities	218,859	335,398
Long-term debt, net	1,208,969	1,213,985
Deferred revenue	28,811	35,523
Liability for pension and other post-retirement benefits	67,913	58,453
Deferred income taxes, net	40,334	38,585
Operating lease liabilities	76,827	117,964
Other long-term liabilities	31,268	36,746
Total liabilities	1,672,981	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 September 30, 2020 and December 31, 2019	0	0
Common stock, $0.01 par value, 500,000,000 shares authorized; 83,076,544 issued and 73,937,777 outstanding at September 30, 2020; 82,601,926 issued and 73,601,950 outstanding at December 31, 2019	827	823
Additional paid-in capital	1,197,464	1,185,116
Retained deficit	(400,061)	(279,956)
Treasury stock, at cost, 9,138,767 and 8,999,976 shares at September 30, 2020 and December 31, 2019, respectively	(181,542)	(180,912)
Accumulated other comprehensive loss	(24,841)	(19,854)
Total U.S. Silica Holdings, Inc. stockholders’ equity	591,847	705,217
Non-controlling interest	11,819	11,363
Total stockholders' equity	603,666	716,580
Total liabilities and stockholders’ equity	$ 2,276,647	$ 2,553,234

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock authorized (in shares)	10,000,000	10,000,000
Preferred stock issued (in shares)	0	0
Preferred stock outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock authorized (in shares)	500,000,000	500,000,000
Common stock issued (in shares)	83,076,544	82,601,926
Common stock outstanding (in shares)	73,937,777	73,601,950
Treasury stock, at cost (in shares)	9,138,767	8,999,976

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Sales:
Total sales	$ 176,472	$ 361,814	$ 618,608	$ 1,135,418
Cost of sales (excluding depreciation, depletion and amortization):
Total cost of sales (excluding depreciation, depletion and amortization)	107,592	283,633	433,652	875,331
Operating expenses:
Selling, general and administrative	27,216	40,208	96,394	113,523
Depreciation, depletion and amortization	40,069	47,126	115,604	136,625
Goodwill and other asset impairments	222	130	108,044	130
Total operating expenses	67,507	87,464	320,042	250,278
Operating income (loss)	1,373	(9,283)	(135,086)	9,809
Other (expense) income:
Interest expense	(19,274)	(24,733)	(63,730)	(72,476)
Other (expense) income, net, including interest income	(409)	3,280	15,592	19,076
Total other expense	(19,683)	(21,453)	(48,138)	(53,400)
Loss before income taxes	(18,310)	(30,736)	(183,224)	(43,591)
Income tax benefit	4,094	7,671	63,785	7,259
Net loss	(14,216)	(23,065)	(119,439)	(36,332)
Less: Net loss attributable to non-controlling interest	(254)	(28)	(778)	(121)
Net loss attributable to U.S. Silica Holdings, Inc.	$ (13,962)	$ (23,037)	$ (118,661)	$ (36,211)
Loss per share attributable to U.S. Silica Holdings, Inc.:
Basic (in dollars per share)	$ (0.19)	$ (0.31)	$ (1.61)	$ (0.49)
Diluted (in dollars per share)	$ (0.19)	$ (0.31)	$ (1.61)	$ (0.49)
Weighted average shares outstanding:
Basic (in shares)	73,688	73,328	73,601	73,223
Diluted (in shares)	73,688	73,328	73,601	73,223
Dividends declared per share (in dollars per share)	$ 0	$ 0.0625	$ 0.02	$ 0.1875
Product
Sales:
Total sales	$ 159,637	$ 287,977	$ 541,998	$ 887,878
Cost of sales (excluding depreciation, depletion and amortization):
Total cost of sales (excluding depreciation, depletion and amortization)	93,747	226,797	373,373	687,186
Service
Sales:
Total sales	16,835	73,837	76,610	247,540
Cost of sales (excluding depreciation, depletion and amortization):
Total cost of sales (excluding depreciation, depletion and amortization)	$ 13,845	$ 56,836	$ 60,279	$ 188,145

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net loss	$ (14,216)	$ (23,065)	$ (119,439)	$ (36,332)
Other comprehensive loss:
Unrealized gain (loss) on derivatives (net of tax of $231 and $156 for the three months ended September 30, 2020 and 2019, respectively, and $973 and $(803) for the nine months ended September 30, 2020 and 2019, respectively)	725	491	3,053	(2,520)
Foreign currency translation adjustment (net of tax of $202 and $(170) for the three months ended September 30, 2020 and 2019, respectively, and $212 and $(181) for the nine months ended September 30, 2020 and 2019, respectively)	631	(543)	662	(577)
Pension and other post-retirement benefits liability adjustment (net of tax of $(1,048) and $(1,270) for the three months ended September 30, 2020 and 2019, respectively, and $(2,773) and $(2,327) for the nine months ended September 30, 2020 and 2019, respectively)	(3,287)	(3,987)	(8,702)	(7,304)
Comprehensive loss	(16,147)	(27,104)	(124,426)	(46,733)
Less: Comprehensive loss attributable to non-controlling interest	(254)	(28)	(778)	(121)
Comprehensive loss attributable to U.S. Silica Holdings, Inc.	$ (15,893)	$ (27,076)	$ (123,648)	$ (46,612)

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Tax expense (benefit) on unrealized (loss) gain on derivatives	$ 231	$ 156	$ 973	$ (803)
Tax expense (benefit) on foreign currency translation adjustment	202	(170)	212	(181)
Tax (expense) benefit on pension and other post-retirement benefits liability adjustment	$ (1,048)	$ (1,270)	$ (2,773)	$ (2,327)

CONDENSED CONSOLIDATED STATEM_4

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 Earnings (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	(36,332)	(36,211)				(36,211)		(121)
Unrealized gain (loss) on derivatives	(2,520)	(2,520)					(2,520)
Foreign currency translation adjustment	(577)	(577)					(577)
Pension and post-retirement liability	(7,304)	(7,304)					(7,304)
Cash dividend declared	(14,138)	(14,138)				(14,138)
Contributions from non-controlling interest	5,185							5,185
Common stock-based compensation plans activity:
Equity-based compensation	10,566	10,566			10,566
Proceeds from options exercised	128	128		295	(167)
Tax payments related to shares withheld for vested restricted stock and stock units	(2,913)	(2,913)	3	(2,913)	(3)
Ending Balance at Sep. 30, 2019	1,004,399	991,851	821	(180,833)	1,179,779	17,505	(25,421)	12,548
Beginning Balance at Jun. 30, 2019	1,032,465	1,019,945	821	(180,775)	1,176,057	45,224	(21,382)	12,520
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(23,065)	(23,037)				(23,037)		(28)
Unrealized gain (loss) on derivatives	491	491					491
Foreign currency translation adjustment	(543)	(543)					(543)
Pension and post-retirement liability	(3,987)	(3,987)					(3,987)
Cash dividend declared	(4,682)	(4,682)				(4,682)
Contributions from non-controlling interest	56							56
Common stock-based compensation plans activity:
Equity-based compensation	3,722	3,722			3,722
Tax payments related to shares withheld for vested restricted stock and stock units	(58)	(58)		(58)
Ending Balance at Sep. 30, 2019	1,004,399	991,851	821	(180,833)	1,179,779	17,505	(25,421)	12,548
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	(119,439)	(118,661)				(118,661)		(778)
Unrealized gain (loss) on derivatives	3,053	3,053					3,053
Foreign currency translation adjustment	662	662					662
Pension and post-retirement liability	(8,702)	(8,702)					(8,702)
Cash dividend declared	(1,444)	(1,444)				(1,444)
Contributions from non-controlling interest	1,234							1,234
Common stock-based compensation plans activity:
Equity-based compensation	12,352	12,352			12,352
Tax payments related to shares withheld for vested restricted stock and stock units	(630)	(630)	4	(630)	(4)
Ending Balance at Sep. 30, 2020	603,666	591,847	827	(181,542)	1,197,464	(400,061)	(24,841)	11,819
Beginning Balance at Jun. 30, 2020	613,268	602,461	826	(181,413)	1,192,068	(386,110)	(22,910)	10,807
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(14,216)	(13,962)				(13,962)		(254)
Unrealized gain (loss) on derivatives	725	725					725
Foreign currency translation adjustment	631	631					631
Pension and post-retirement liability	(3,287)	(3,287)					(3,287)
Cash dividend declared	11	11				11
Contributions from non-controlling interest	1,266							1,266
Common stock-based compensation plans activity:
Equity-based compensation	5,397	5,397			5,397
Tax payments related to shares withheld for vested restricted stock and stock units	(129)	(129)	1	(129)	(1)
Ending Balance at Sep. 30, 2020	$ 603,666	$ 591,847	$ 827	$ (181,542)	$ 1,197,464	$ (400,061)	$ (24,841)	$ 11,819

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - $ / shares	3 Months Ended			9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Stockholders' Equity [Abstract]
Cash dividend declared (in dollars per share)	$ 0	$ 0	$ 0.0625	$ 0.02	$ 0.1875

CONDENSED CONSOLIDATED STATEM_6

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Operating activities:
Net loss	$ (119,439)	$ (36,332)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation, depletion and amortization	115,604	136,625
Goodwill and other asset impairments	108,044	130
Gain on valuation change of royalty note payable	0	(16,104)
Debt issuance amortization	3,855	4,304
Original issue discount amortization	778	792
Deferred income taxes	(65,645)	(8,489)
Deferred revenue	(6,292)	(32,379)
(Gain) loss on disposal of property, plant and equipment	(1,785)	58
Gain on early extinguishment of debt	0	(81)
Equity-based compensation	12,352	10,566
Provision for credit losses, net of recoveries	1,381	3,082
Gain on remeasurement of leases	(24,415)	0
Other	(2,381)	(13,197)
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable	81,234	3,792
Inventories	15,218	(35)
Prepaid expenses and other current assets	(25,384)	8,460
Income taxes	804	(396)
Accounts payable and accrued expenses	(102,449)	39,456
Short-term and long-term obligations-vendor incentives	0	4,021
Liability for pension and other post-retirement benefits	9,053	9,063
Other noncurrent assets and liabilities	(34,976)	3,045
Net cash (used in) provided by operating activities	(34,443)	116,381
Investing activities:
Capital expenditures	(27,751)	(97,902)
Capitalized intellectual property costs	(531)	(3,493)
Proceeds from sale of property, plant and equipment	2,749	1,543
Net cash used in investing activities	(25,533)	(99,852)
Financing activities:
Dividends paid	(6,169)	(13,880)
Proceeds from options exercised	0	128
Tax payments related to shares withheld for vested restricted stock and stock units	(630)	(2,913)
Proceeds from draw down of the Revolver	25,000	0
Payments on long-term debt	(10,235)	(20,207)
Contributions from non-controlling interest	1,234	5,185
Principal payments on finance lease obligations	(41)	(51)
Net cash provided by (used in) financing activities	9,159	(31,738)
Net decrease in cash and cash equivalents	(50,817)	(15,209)
Cash and cash equivalents, beginning of period	185,740	202,498
Cash and cash equivalents, end of period	134,923	187,289
Cash paid (received) during the period for:
Interest	57,107	66,429
Taxes, net of refunds	(35,676)	(14,031)
Non-cash items:
Accrued capital expenditures	15,111	27,357
Net assets assumed in business acquisition	$ 8,241	$ 0

Organization and Basis of Prese

Organization and Basis of Presentation	9 Months Ended
Organization and Basis of Presentation	Sep. 30, 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 September 30, 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 September 30, 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 September 30, 2020, the VIE had total assets of $17.9 million and total liabilities of $0.1 million. We made $0.2 million in capital contributions during the nine months ended September 30, 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.”

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
Summary of Significant Accounting Policies	Sep. 30, 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 credit losses; 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 Accounting Standards Update ("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 was 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 was 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 aligned 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 ASU 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 consolidated financial statements and related disclosures.

Earnings Per Share

Earnings Per Share	9 Months Ended
Earnings Per Share	Sep. 30, 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 and nine months ended September 30, 2020 and 2019: In thousands, except per share amounts Three Months Ended Nine Months Ended 2020 2019 2020 2019 Numerator: Net loss attributable to U.S. Silica Holdings, Inc. $ (13,962) $ (23,037) $ (118,661) $ (36,211) Denominator: Weighted average shares outstanding 73,688 73,328 73,601 73,223 Diluted effect of stock awards — — — — Weighted average shares outstanding assuming dilution 73,688 73,328 73,601 73,223 Loss per share attributable to U.S. Silica Holdings, Inc.: Basic loss per share $ (0.19) $ (0.31) $ (1.61) $ (0.49) Diluted loss per share $ (0.19) $ (0.31) $ (1.61) $ (0.49) Potentially dilutive shares (in thousands) of 348 and 91 for the three months ended September 30, 2020 and 2019, respectively, and 173 and 191 for the nine months ended September 30, 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 excluded from the calculation of diluted loss per common share were as follows: In thousands Three Months Ended Nine Months Ended 2020 2019 2020 2019 Stock options excluded 826 700 826 716 Restricted stock and performance share unit awards excluded 2,667 265 4,103 280

Capital Structure and Accumulat

Capital Structure and Accumulated Other Comprehensive Income (Loss)	9 Months Ended
	Sep. 30, 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 83,076,544 shares issued and 73,937,777 shares outstanding at September 30, 2020. There were 82,601,926 shares issued and 73,601,950 shares outstanding at December 31, 2019. During the nine months ended September 30, 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. During May of 2020, our Board of Directors determined that it was not in the best interest of our shareholders to issue a dividend for the second quarter of 2020 and they subsequently decided not to issue a dividend for the third quarter of 2020. The Board of Directors will make determinations regarding future dividends on a quarterly basis using the criteria described above. 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 September 30, 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 September 30, 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. We did not repurchase any shares during the nine months ended September 30, 2020. 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 nine months ended September 30, 2020: For the Nine Months Ended September 30, 2020 Unrealized (loss) 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 gain (loss) before reclassifications 3,053 662 (10,498) (6,783) Amounts reclassified from accumulated other comprehensive loss — — 1,796 1,796 Ending Balance $ — $ (146) $ (24,695) $ (24,841) 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.

Business Combinations

Business Combinations	9 Months Ended
Business Combinations	Sep. 30, 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. In the three months ended September 30, 2020, we recorded a $0.1 million increase to accounts receivable. In the nine months ended September 30, 2020, we recorded a $3.3 million decrease in inventory, a $1.0 million increase to accounts receivable, and a $0.1 million decrease to property, plant and equipment. The total measurement period adjustments during the nine months ended September 30, 2020 of $2.4 million were recorded as a net decrease to the initial gain on bargain purchase and recorded in "Other (expense) income, net, including interest income" in the Condensed Consolidated Statement of Operations.

Accounts Receivable

Accounts Receivable	9 Months Ended
Accounts Receivable	Sep. 30, 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 September 30, 2020 and December 31, 2019, accounts receivable (in thousands) consisted of the following: September 30, December 31, Trade receivables $ 133,127 $ 178,182 Less: Allowance for credit losses (6,677) (8,984) Net trade receivables 126,450 169,198 Other receivables (1) 47,377 13,040 Total accounts receivable $ 173,827 $ 182,238 (1) At September 30, 2020, other receivables included $42.3 million of refunds related to NOL carryback claims filed for various tax years in accordance with certain provisions of the CARES Act. 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 & Specialty 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 reflects the change of the allowance for credit losses (in thousands) for the nine months ended September 30, 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 1,340 41 1,381 Write-offs (3,328) (360) (3,688) Ending balance, September 30, 2020 $ 5,652 $ 1,025 $ 6,677 Our ten largest customers accounted for 23% and 32% of total sales for the three and nine months ended September 30, 2020, respectively, and 43% and 42% for the three and nine months ended September 30, 2019, respectively. No customers accounted for 10% or more of our total sales for the three or nine months ended September 30, 2020. Sales to one of our customers accounted for 11% and 12% for the three and nine months ended September 30, 2019, respectively. No other customers accounted for 10% or more of our total sales during the same period. At September 30, 2020, one of our customer's accounts receivable represented 15% of our total trade accounts receivable. At December 31, 2019, the same customer's accounts receivable represented 12% of our total trade accounts receivable. No other customers accounted for 10% or more of our total trade accounts receivable during the same period.

Inventories

Inventories	9 Months Ended
Inventories	Sep. 30, 2020
Inventory Disclosure [Abstract]
INVENTORIES	NOTE G—INVENTORIES At September 30, 2020 and December 31, 2019, inventories (in thousands) consisted of the following: September 30, 2020 December 31, 2019 Supplies $ 43,331 $ 47,277 Raw materials and work in process 34,544 41,167 Finished goods 26,836 35,988 Total inventories $ 104,711 $ 124,432 During 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 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 zero and $6.7 million for the three and nine months ended September 30, 2020, respectively, primarily related to unused inventory at idled plants. These charges related to the Oil & Gas Proppants Segment and were recorded in "Goodwill and other asset impairments" in the Condensed Consolidated Statements of Operations.

Property, Plant and Mine Develo

Property, Plant and Mine Development	9 Months Ended
Property, Plant and Mine Development	Sep. 30, 2020
Property, Plant and Equipment [Abstract]
PROPERTY, PLANT AND MINE DEVELOPMENT	NOTE H—PROPERTY, PLANT AND MINE DEVELOPMENT At September 30, 2020 and December 31, 2019, property, plant and mine development (in thousands) consisted of the following: September 30, December 31, Mining property and mine development $ 788,710 $ 794,899 Asset retirement cost 18,011 18,260 Land 55,281 57,082 Land improvements 75,878 73,203 Buildings 69,492 69,112 Machinery and equipment 1,179,002 1,152,898 Furniture and fixtures 4,071 4,068 Construction-in-progress 34,034 54,675 2,224,479 2,224,197 Accumulated depreciation, depletion, amortization and impairment charges (808,843) (706,610) Total property, plant and mine development, net $ 1,415,636 $ 1,517,587 Depreciation, depletion, and amortization expense related to property, plant and mine development was $37.3 million and $44.0 million for the three months ended September 30, 2020 and 2019, respectively, and $106.6 million and $127.3 million for the nine months ended September 30, 2020 and 2019, respectively. The amount of interest costs capitalized in property, plant and mine development was $33 thousand and $1.9 million for the nine months ended September 30, 2020 and 2019, respectively. During 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 zero and $11.6 million for the three and nine months ended September 30, 2020, respectively, 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 September 30, 2020, vendor incentives of $9.6 million were classified in accounts payable and accrued expenses on our balance sheet. During 2020, management approved the disposal of certain non-operating parcels of land. The assets, which have a combined carrying value of approximately $2.2 million, have been classified as assets held for sale and are presented within Prepaid expenses and other current assets in the Condensed Consolidated Balance Sheets. The proceeds of the disposals are expected to equal or exceed the net carrying value of the assets and, accordingly, no impairment loss has been recognized on these assets held for sale. The assets were previously classified as Land, therefore, no adjustments were needed for depreciation of these assets. We expect to dispose of these assets within one year of the balance sheet date.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	9 Months Ended
Goodwill and Intangible Assets	Sep. 30, 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 September 30, 2020 $ — $ 185,649 $ 185,649 (1) During the first quarter of 2020, an 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 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 during the first quarter of 2020, which were recorded in "Goodwill and other asset impairments" in the Condensed Consolidated Statements of Operations. We have performed qualitative analysis in subsequent periods and determined no further impairments were necessary. The changes in the carrying amount of intangible assets (in thousands) consisted of the following: September 30, 2020 December 31, 2019 Gross Carrying Amount Accumulated Amortization Impairments Net Gross Carrying Amount Accumulated Amortization Impairments Net Technology and intellectual property $ 72,801 $ (19,278) $ — $ 53,523 $ 86,183 $ (17,080) $ — $ 69,103 Customer relationships 66,999 (21,980) — 45,019 68,599 (18,737) (1,240) 48,622 Total definite-lived intangible assets: $ 139,800 $ (41,258) $ — $ 98,542 $ 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: $ 205,890 $ (41,258) $ — $ 164,632 $ 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. During the second quarter of 2020, we expensed $11.8 million of capitalized legal fees related to the unsuccessful defense of a small number of our patents. These charges related to the Oil & Gas Proppants segment and were recorded in Selling, general and administrative expense in the Condensed Consolidated Statement of Operations. Amortization expense was $2.5 million and $7.9 million for the three and nine months ended September 30, 2020, respectively. Amortization expense was $2.7 million and $8.1 million for the three and nine months ended September 30, 2019, respectively. The estimated amortization expense related to definite-lived intangible assets (in thousands) for the five succeeding years is as follows: 2020 (remaining three months) $ 2,718 2021 10,866 2022 10,851 2023 10,846 2024 10,848

Debt

Debt	9 Months Ended
Debt	Sep. 30, 2020
Debt Disclosure [Abstract]
DEBT	NOTE J—DEBT At September 30, 2020 and December 31, 2019, debt (in thousands) consisted of the following: September 30, December 31, Senior secured credit facility: Revolver expiring May 1, 2023 (4.19% at September 30, 2020 and 7.75% at December 31, 2019) $ 25,000 $ — Term Loan—final maturity May 1, 2025 (5.00% at September 30, 2020 and 5.81% at December 31, 2019) 1,238,000 1,247,600 Less: Unamortized original issue discount (4,634) (5,412) Less: Unamortized debt issuance cost (21,535) (25,390) Note payable secured by royalty interest 10,813 10,438 Insurance financing notes payable 5,573 5,055 Equipment notes payable — 87 Finance leases — 70 Total debt 1,253,217 1,232,448 Less: current portion (44,248) (18,463) Total long-term portion of debt $ 1,208,969 $ 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 September 30, 2020 and December 31, 2019, we are in compliance with all covenants in accordance with our senior secured Credit Facility. Term Loan At September 30, 2020, contractual maturities of our Term Loan (in thousands) are as follows: 2020 (remaining three months) $ 3,200 2021 12,800 2022 12,800 2023 12,800 2024 12,800 Thereafter 1,183,600 Total $ 1,238,000 Revolving Line-of-Credit We have a $100.0 million Revolver with $25.0 million drawn and $25.4 million allocated for letters of credit as of September 30, 2020, leaving $49.6 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 September 30, 2020 has been classified as current. Based on our consolidated leverage ratio of 5.85:1.00 as of September 30, 2020, we may draw up to approximately $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 three months) $ 945 2021 367 2022 423 2023 487 2024 557 Thereafter 8,034 Total $ 10,813 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 September 30, 2020. As of September 30, 2020, the note payable had a balance of $10.8 million. Changes in fair value of the note payable amount may result if estimates of future tonnages and sales increase or decrease. Subsequent to September 30, 2020, we executed an amendment to the note payable which settled the outstanding balance in its entirety in exchange for a one time payment of $2.55 million. Future royalties may be owed under this amended agreement if we resume production at our Tyler facility, however, we have no such plans to resume production in the near term. Therefore, no amounts have been accrued. Insurance Financing Notes Payable During September 2020, the Company renewed its insurance policies and financed the payments through notes payable with a stated interest rate of 3.0%. These payments will be made in installments throughout a nine-month period and, as such, have been classified as current debt. As of September 30, 2020, the notes payable had a balance of $5.6 million.

Asset Retirement Obligations

Asset Retirement Obligations	9 Months Ended
Asset Retirement Obligations	Sep. 30, 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 September 30, 2020 and 2019, we had a liability of $26.0 million and $20.6 million, respectively, in other long-term liabilities related to our asset retirement obligations. Changes in the asset retirement obligations (in thousands) during the nine months ended September 30, 2020 and 2019 are as follows: Nine Months Ended 2020 2019 Beginning balance $ 25,825 $ 18,413 Accretion 1,098 1,138 Additions and revisions of estimates (890) 1,061 Ending balance $ 26,033 20,612

Fair Value Accounting

Fair Value Accounting	9 Months Ended
Fair Value Accounting	Sep. 30, 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 September 30, 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 is 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, 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,

Derivative Instruments

Derivative Instruments	9 Months Ended
Derivative Instruments	Sep. 30, 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 September 30, 2020, the fair values of our two interest rate swaps were both zero as our swap agreements matured on July 31, 2020. 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 designated the interest rate swap agreements as qualified cash flow hedges. Accordingly, the effective portion of the gain or loss on the derivative instrument was reported as a component of other comprehensive income and recognized in earnings in the same period or periods during which the hedged transaction affects earnings. The following table summarizes the fair values 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 September 30, 2020 and December 31, 2019. September 30, 2020 December 31, 2019 Maturity Contract/Notional Carrying Fair Maturity Date Contract/Notional Carrying Fair LIBOR (1) interest rate swap agreement 2020 $440 million $ — $ — 2020 $440 million $ (2,768) $ (2,768) LIBOR (1) interest rate swap agreement 2020 $200 million $ — $ — 2020 $200 million $ (1,259) $ (1,259) (1) Agreements fix the LIBOR interest rate base to 2.74%. During the nine months ended September 30, 2020, we had no ineffectiveness for the interest rate swap derivatives. The following table summarizes the effect of derivative instruments (in thousands) on our income statements and our consolidated statements of comprehensive income for the nine months ended September 30, 2020 and 2019: Nine Months Ended 2020 2019 Deferred losses from derivatives in OCI, beginning of period $ (3,053) $ (1,621) Gain (loss) recognized in OCI from derivative instruments 3,053 (2,520) Deferred losses from derivatives in OCI, end of period $ — $ (4,141)

Equity-Based Compensation

Equity-Based Compensation	9 Months Ended
Equity-Based Compensation	Sep. 30, 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 and amended and restated effective February 1, 2020. 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 September 30, 2020, we have 3,787,156 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 nine months ended September 30, 2020: Number of Weighted Aggregate Intrinsic Value Weighted Outstanding at December 31, 2019 826,658 $ 28.97 $ 11,557 4.1 years Granted — $ — $ — Exercised — $ — $ — Forfeited (443) $ 32.41 $ — Expired — $ — $ — Outstanding at September 30, 2020 826,215 $ 29.05 $ — 3.3 years Exercisable at September 30, 2020 826,215 $ 29.05 $ — 3.3 years There were no grants of stock options during the three and nine months ended September 30, 2020 and 2019. There were zero stock options exercised during the three and nine months ended September 30, 2020, respectively. There were zero and 10,000 stock options exercised during the three and nine months ended September 30, 2019. The total intrinsic value of stock options exercised was $12 thousand for the nine months ended September 30, 2019. Cash received from stock options exercised during the nine months ended September 30, 2019 was $128 thousand. The tax benefit realized from stock option exercises was $3 thousand for the nine months ended September 30, 2019. As of September 30, 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 nine months ended September 30, 2020: Number of Shares Grant Date Weighted Unvested, December 31, 2019 1,020,248 $ 15.86 Granted 1,541,473 $ 4.13 Vested (490,414) $ 16.61 Forfeited (281,134) $ 10.54 Unvested, September 30, 2020 1,790,173 $ 6.45 We granted 49,696 and 1,541,473 restricted stock and restricted stock unit awards during the three and nine months ended September 30, 2020, respectively. We granted 34,790 and 791,903 restricted stock and restricted stock unit awards during the three and nine months ended September 30, 2019, respectively. The fair value of the awards was based on the market price of our stock at date of grant. We recognized $2.7 million and $6.6 million of equity-based compensation expense related to restricted stock awards during the three and nine months ended September 30, 2020, respectively. We recognized $2.0 million and $6.4 million of equity-based compensation expense related to restricted stock awards during the three and nine months ended September 30, 2019, respectively. As of September 30, 2020, there was $8.0 million of unrecognized compensation expense related to these restricted stock awards, which is expected to be recognized over a weighted-average period of 1.7 years. We also granted zero and 335,039 awards, which included 58,246 forfeited and partially vested awards, during the three and nine months ended September 30, 2020, respectively. These awards will vest over a period of three years and will be settled in cash. As such, these awards have been classified as liability instruments. We recognized $0.1 million and $0.2 million of expense related to these awards for the three and nine months ended September 30, 2020, respectively. 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 $0.7 million over a period of 2.4 years. Performance Share Unit Awards The following table summarizes the status of, and changes in, our performance share unit awards during the nine months ended September 30, 2020: Number of Shares Grant Date Weighted Unvested, December 31, 2019 838,722 $ 18.00 Granted 1,020,161 $ 9.94 Vested — $ — Forfeited/Cancelled (341,221) $ 25.88 Unvested, September 30, 2020 1,517,662 $ 14.28 We granted zero and 1,020,161 performance share units during the three and nine months ended September 30, 2020, respectively. We granted zero and 607,130 performance share units during the three and nine months ended September 30, 2019, respectively. 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 $2.7 million and $5.7 million of compensation expense related to performance share unit awards during the three and nine months ended September 30, 2020, respectively. We recognized $1.8 million and $4.3 million of compensation expense related to performance share unit awards during the three and nine months ended September 30, 2019, respectively. As of September 30, 2020, there was $10.8 million of unrecognized compensation expense related to these performance share unit awards, which is expected to be recognized over a weighted-average period of 1.9 years. We also granted cash awards during the nine months ended September 30, 2020. These awards will vest over a period of 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 nine months ended September 30, 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 $1.5 million over a period of 2.4 years.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	NOTE O—COMMITMENTS AND CONTINGENCIES Future Minimum Annual Commitments at September 30, 2020 (in thousands): Minimum Purchase Commitments 2020 (remaining three months) $ 1,864 2021 13,542 2022 10,328 2023 10,328 2024 7,020 Thereafter 10,147 Total future purchase commitments $ 53,229 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 nine months ended September 30, 2020, zero new claims were brought against U.S. Silica. As of September 30, 2020, there were 54 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 September 30, 2020 and December 31, 2019, other non-current assets included zero for insurance for third-party product liability claims. As of September 30, 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 September 30, 2020, there was $35.1 million in bonds outstanding, of which $31.1 million relate to reclamation requirements issued by various governmental authorities. Reclamation bonds remain outstanding until the mining area is reclaimed and the authority issues a formal release. The remaining bonds relate to licenses, permits, and tax collection.

Pension and Post-Retirement Ben

Pension and Post-Retirement Benefits	9 Months Ended
Pension and Post-Retirement Benefits	Sep. 30, 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. 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 and nine months ended September 30, 2020 and 2019: Three Months Ended Nine Months Ended 2020 2019 2020 2019 Service cost $ 199 $ 323 $ 1,515 $ 1,065 Interest cost 356 1,503 2,349 4,813 Expected return on plan assets (531) (1,727) (3,394) (5,745) Net amortization and deferral 276 459 2,078 1,305 Net pension benefit costs $ 300 $ 558 $ 2,548 $ 1,438 Net post-retirement benefit cost (in thousands) consisted of the following for the three and nine months ended September 30, 2020 and 2019: Three Months Ended Nine Months Ended 2020 2019 2020 2019 Service cost $ 28 $ 20 $ 65 $ 67 Interest cost 235 182 426 572 Unrecognized net (gain)/loss — (7) — (7) Net post-retirement benefit costs $ 263 $ 195 $ 491 $ 632 We contributed $2.2 million and $4.2 million to the qualified pension plans for the three and nine months ended September 30, 2020, respectively. We contributed $2.1 million and $3.8 million to the qualified pension plans for the three and nine months ended September 30, 2019, respectively. Our best estimates 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 and nine months ended September 30, 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 $0.6 million and $2.8 million for the three and nine months ended September 30, 2020, respectively. Contributions were $1.5 million and $4.8 million for the three and nine months ended September 30, 2019, respectively.

Leases

Leases	9 Months Ended
Leases	Sep. 30, 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 (in thousands, except lease term and discount rate): Leases Classification September 30, December 31, 2019 Assets Operating Operating lease right-of-use assets $ 41,265 $ 53,098 Total leased right-of-use assets $ 41,265 $ 53,098 Liabilities Current Operating Current portion of operating lease liabilities $ 30,887 $ 53,587 Non-current Operating Operating lease liabilities 76,827 117,964 Total lease liabilities $ 107,714 $ 171,551 Lease Term and Discount Rate Weighted average remaining lease term: Operating leases 5.2 years 4.5 years Weighted average discount rate: Operating leases 5.7% 5.7% During 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 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 $0.2 million and $3.4 million for the three and nine months ended September 30, 2020, respectively, primarily related to railcar leases, various equipment leases and an office building lease. These charges related to the Oil & Gas Proppants Segment and were recorded in "Goodwill and other asset impairments" in the Condensed Consolidated Statements of Operations. During the second and third quarters of 2020, we received lease concessions from certain lessors. Based on accounting elections provided by the FASB and in accordance with ASC 842-10, we have not accounted for these concessions as lease modifications. Based on remeasurement of the amended leases, for the three and nine months ended September 30, 2020, we recorded a decrease to the ROU asset of $0.4 million and $0.9 million, respectively, and a decrease to the liability of $20.9 million and $25.0 million, respectively. A gain of $20.5 million and $24.4 million was recognized as operating income through cost of goods sold in our income statements for the three and nine months ended September 30, 2020, respectively. The components of lease expense (in thousands) were as follows: Lease Costs Classification Three Months Ended Three Months Ended Nine Months Ended Nine Months Ended Operating lease costs (1) Cost of sales $ 5,711 $ 21,787 $ 21,417 $ 69,547 Operating lease costs (2) Selling, general and administrative 415 1,044 1,420 3,281 Total $ 6,126 $ 22,831 $ 22,837 $ 72,828 (1) Included short-term operating lease costs of $0.3 million and $7.5 million for the three and nine months ended September 30, 2020, respectively. Included short-term operating lease costs of $4.0 million and $15.1 million for the three and nine months ended September 30, 2019, respectively. (2) Included short-term operating lease costs of $0.1 million and $0.3 million for the three and nine months ended September 30, 2020, respectively. Included short-term operating lease costs of $0.2 million and $0.6 million for the three and nine months ended September 30, 2019, respectively. Supplemental cash flow information (in thousands) related to leases was as follows: Nine Months Ended Nine Months Ended Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows for operating leases $ 51,859 $ 57,523 Right-of-use assets obtained in exchange for new lease liabilities: Operating leases $ 10,650 $ 229,557 Maturities of lease liabilities (in thousands) as of September 30, 2020: Operating leases 2020 (remaining three months) $ 10,757 2021 32,226 2022 18,572 2023 15,676 2024 12,716 Thereafter 46,823 Total lease payments $ 136,770 Less: Interest 29,056 Total $ 107,714
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 (in thousands, except lease term and discount rate): Leases Classification September 30, December 31, 2019 Assets Operating Operating lease right-of-use assets $ 41,265 $ 53,098 Total leased right-of-use assets $ 41,265 $ 53,098 Liabilities Current Operating Current portion of operating lease liabilities $ 30,887 $ 53,587 Non-current Operating Operating lease liabilities 76,827 117,964 Total lease liabilities $ 107,714 $ 171,551 Lease Term and Discount Rate Weighted average remaining lease term: Operating leases 5.2 years 4.5 years Weighted average discount rate: Operating leases 5.7% 5.7% During 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 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 $0.2 million and $3.4 million for the three and nine months ended September 30, 2020, respectively, primarily related to railcar leases, various equipment leases and an office building lease. These charges related to the Oil & Gas Proppants Segment and were recorded in "Goodwill and other asset impairments" in the Condensed Consolidated Statements of Operations. During the second and third quarters of 2020, we received lease concessions from certain lessors. Based on accounting elections provided by the FASB and in accordance with ASC 842-10, we have not accounted for these concessions as lease modifications. Based on remeasurement of the amended leases, for the three and nine months ended September 30, 2020, we recorded a decrease to the ROU asset of $0.4 million and $0.9 million, respectively, and a decrease to the liability of $20.9 million and $25.0 million, respectively. A gain of $20.5 million and $24.4 million was recognized as operating income through cost of goods sold in our income statements for the three and nine months ended September 30, 2020, respectively. The components of lease expense (in thousands) were as follows: Lease Costs Classification Three Months Ended Three Months Ended Nine Months Ended Nine Months Ended Operating lease costs (1) Cost of sales $ 5,711 $ 21,787 $ 21,417 $ 69,547 Operating lease costs (2) Selling, general and administrative 415 1,044 1,420 3,281 Total $ 6,126 $ 22,831 $ 22,837 $ 72,828 (1) Included short-term operating lease costs of $0.3 million and $7.5 million for the three and nine months ended September 30, 2020, respectively. Included short-term operating lease costs of $4.0 million and $15.1 million for the three and nine months ended September 30, 2019, respectively. (2) Included short-term operating lease costs of $0.1 million and $0.3 million for the three and nine months ended September 30, 2020, respectively. Included short-term operating lease costs of $0.2 million and $0.6 million for the three and nine months ended September 30, 2019, respectively. Supplemental cash flow information (in thousands) related to leases was as follows: Nine Months Ended Nine Months Ended Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows for operating leases $ 51,859 $ 57,523 Right-of-use assets obtained in exchange for new lease liabilities: Operating leases $ 10,650 $ 229,557 Maturities of lease liabilities (in thousands) as of September 30, 2020: Operating leases 2020 (remaining three months) $ 10,757 2021 32,226 2022 18,572 2023 15,676 2024 12,716 Thereafter 46,823 Total lease payments $ 136,770 Less: Interest 29,056 Total $ 107,714

Income Taxes

Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 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. 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. As a result, we have carried the NOL generated in 2019 back to offset the taxable income in the 2014 tax year generating a refund of $36.6 million. This refund was received at the end of the second quarter. We have also amended our 2018 tax return to generate an NOL by electing bonus depreciation. We then carried the NOL generated in 2018 back to offset the taxable income in prior years generating a refund of $26.3 million. This refund has been reclassified from deferred tax asset to accounts receivable in our balance sheets as of September 30, 2020. The deferred tax assets related to the NOLs generated in 2018 and 2019 were recorded at the statutory income tax rate for 2018 and 2019, which was 21% for both years. As a result of the carry back of these NOLs to prior years, the NOLs will be utilized at the statutory income tax rate for pre-2018, which was 35%. This increase in the tax rate at which the 2018 and 2019 NOLs will be utilized results in a deferred tax benefit. Accordingly, during the nine months ended September 30, 2020, we recorded a deferred tax benefit of $22.3 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 has been reclassified from deferred tax asset to accounts receivable to reflect the timing of when the credits are expected to be monetized. AMT credits in the amount of $16.0 million are included in accounts receivable on our balance sheets as of September 30, 2020. 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 did not have a material impact to the third 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 Operations. For the three and nine months ended September 30, 2020, we had tax benefits of $4.1 million and $63.8 million, respectively. For the three and nine months ended September 30, 2019, we had tax benefits of $7.7 million and $7.3 million, respectively. The effective tax rate was 22% and 35% for the three and nine months ended September 30, 2020, respectively. The effective tax rate was 25% and 17% for the three and nine months ended September 30, 2019, respectively. Without discrete items, which primarily consist of tax expense related to equity compensation and tax benefits related to the carryback of NOLs described above, the effective tax rate for the three and nine months ended September 30, 2020 would have been 26% and 24%, respectively. Without discrete items, the effective tax rate for the three and nine months ended September 30, 2019 would have been 27% and 29%, respectively. During the three and nine months ended September 30, 2020, we recorded tax expense related to equity compensation of $0.3 million and $1.7 million, respectively. During the three and nine months ended September 30, 2019, we recorded tax expense related to equity compensation of $0.1 million and $4.5 million, respectively.

Revenue

Revenue	9 Months Ended
Revenue	Sep. 30, 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 and nine months ended September 30, 2020 and 2019 (in thousands): Three Months Ended Three Months Ended Category Oil & Gas Proppants Industrial & Specialty Products Total Sales Oil & Gas Proppants Industrial & Specialty Products Total Sales Product $ 49,508 $ 110,129 $ 159,637 $ 168,870 $ 119,107 $ 287,977 Service 16,835 — 16,835 73,837 — 73,837 Total Sales $ 66,343 $ 110,129 $ 176,472 $ 242,707 $ 119,107 $ 361,814 Nine Months Ended Nine Months Ended Category Oil & Gas Proppants Industrial & Specialty Products Total Sales Oil & Gas Proppants Industrial & Specialty Products Total Sales Product $ 217,943 $ 324,055 $ 541,998 $ 528,708 $ 359,170 $ 887,878 Service 76,610 — 76,610 247,540 — 247,540 Total Sales $ 294,553 $ 324,055 $ 618,608 $ 776,248 $ 359,170 $ 1,135,418 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 nine months ended September 30, 2020 and 2019 (in thousands): Unbilled Receivables September 30, 2020 September 30, 2019 Beginning Balance $ 144 $ 90 Reclassifications to billed receivables (350) (3,183) Revenues recognized in excess of period billings 1,226 3,893 Ending Balance $ 1,020 $ 800 Deferred Revenue September 30, 2020 September 30, 2019 Beginning Balance $ 50,634 $ 113,319 Revenues recognized from balances held at the beginning of the period (7,259) (24,241) Revenues deferred from period collections on unfulfilled performance obligations 4,782 12,225 Revenues recognized from period collections (3,815) (8,138) Ending Balance $ 44,342 $ 93,165 We have elected to use the practical expedients allowed under ASC 606-10-50-14, pursuant to which we have excluded disclosures of transaction prices allocated to remaining performance obligations and when we expect to recognize such revenue. The majority of our remaining performance obligations are primarily comprised of unfulfilled product, transportation service, and labor service orders, all of which hold a remaining duration of less than one year. The long-term portion of deferred revenue primarily represents a combination of refundable and nonrefundable customer prepayments for which related current performance obligations do not yet exist, but are expected to arise, before the expiration of the contract. Our residual unfulfilled performance obligations are comprised primarily of long-term equipment rental arrangements in which we recognize revenues equal to what we have a right to invoice. Generally, no variable consideration exists related to our remaining performance obligations and no consideration is excluded from the associated transaction prices. However, the decrease in the current year deferred revenue balance is partially attributable to revenue recognized as variable consideration from shortfall penalties assessed to multiple customers according to contract terms. During the three and nine months ending September 30, 2020, we have recognized revenue as variable consideration from shortfall penalties according to contract terms in the amounts of $2.2 million and $19.8 million, respectively, of which $1.5 million and $3.0 million, respectively, were included in deferred revenue. In some cases, amounts recorded are estimates which are in negotiation and may increase or decrease. Foreign Operations The following table includes information related to our foreign operations for the three and nine months ended September 30, 2020 and 2019 (in thousands): Three Months Ended Three Months Ended Nine Months Ended Nine Months Ended Total Sales $ 22,084 $ 26,081 $ 65,948 $ 73,589 Pre-tax income $ 3,220 $ 3,491 $ 11,299 $ 10,309 Net income $ 2,544 $ 2,758 $ 8,927 $ 8,144 Foreign operations constituted approximately $32.8 million and $28.4 million of consolidated assets as of September 30, 2020 and 2019, respectively.

Related Party Transactions

Related Party Transactions	9 Months Ended
Related Party Transactions	Sep. 30, 2020
Related Party Transactions [Abstract]
RELATED PARTY TRANSACTIONS	NOTE T— RELATED PARTY TRANSACTIONS There were no related party transactions during the three and nine months ended September 30, 2020 or 2019.

Segment Reporting

Segment Reporting	9 Months Ended
Segment Reporting	Sep. 30, 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. 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 and nine months ended September 30, 2020 and 2019: Three Months Ended Nine Months Ended 2020 2019 2020 2019 Sales: Oil & Gas Proppants $ 66,343 $ 242,707 $ 294,553 $ 776,248 Industrial & Specialty Products 110,129 119,107 324,055 359,170 Total sales 176,472 361,814 618,608 1,135,418 Segment contribution margin: Oil & Gas Proppants 31,478 50,557 90,540 180,601 Industrial & Specialty Products 42,353 44,397 120,821 139,103 Total segment contribution margin 73,831 94,954 211,361 319,704 Operating activities excluded from segment cost of sales (4,951) (16,773) (26,405) (59,617) Selling, general and administrative (27,216) (40,208) (96,394) (113,523) Depreciation, depletion and amortization (40,069) (47,126) (115,604) (136,625) Goodwill and other asset impairments (222) (130) (108,044) (130) Interest expense (19,274) (24,733) (63,730) (72,476) Other (expense) income, net, including interest income (409) 3,280 15,592 19,076 Income tax benefit 4,094 7,671 63,785 7,259 Net loss $ (14,216) $ (23,065) $ (119,439) $ (36,332) Less: Net loss attributable to non-controlling interest (254) (28) (778) (121) Net loss attributable to U.S. Silica Holdings, Inc. $ (13,962) $ (23,037) $ (118,661) $ (36,211)

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 2020
Accounting Policies [Abstract]
Basis of Presentation	The accompanying unaudited Condensed Consolidated Financial Statements for the quarter ended September 30, 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 September 30, 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 credit losses; estimates of fair value for certain reporting units and asset
New Accounting Pronouncements Recently Adopted and New Accounting Pronouncements Not Yet Adopted	New Accounting Pronouncements Recently Adopted In August 2018, the FASB issued Accounting Standards Update ("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 was 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 was 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 aligned 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 ASU 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 consolidated 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 September 30, 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 is 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, 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,

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
Earnings Per Share (Tables)	Sep. 30, 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 and nine months ended September 30, 2020 and 2019: In thousands, except per share amounts Three Months Ended Nine Months Ended 2020 2019 2020 2019 Numerator: Net loss attributable to U.S. Silica Holdings, Inc. $ (13,962) $ (23,037) $ (118,661) $ (36,211) Denominator: Weighted average shares outstanding 73,688 73,328 73,601 73,223 Diluted effect of stock awards — — — — Weighted average shares outstanding assuming dilution 73,688 73,328 73,601 73,223 Loss per share attributable to U.S. Silica Holdings, Inc.: Basic loss per share $ (0.19) $ (0.31) $ (1.61) $ (0.49) Diluted loss per share $ (0.19) $ (0.31) $ (1.61) $ (0.49)
Schedule of Antidilutive Securities Excluded from Computation of Diluted Earnings Per Share	Stock awards excluded from the calculation of diluted loss per common share were as follows: In thousands Three Months Ended Nine Months Ended 2020 2019 2020 2019 Stock options excluded 826 700 826 716 Restricted stock and performance share unit awards excluded 2,667 265 4,103 280

Capital Structure and Accumul_2

Capital Structure and Accumulated Other Comprehensive Income (Loss) (Tables)	9 Months Ended
	Sep. 30, 2020
Equity [Abstract]
Schedule of Declared Quarterly Cash Dividends	During the nine months ended September 30, 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 nine months ended September 30, 2020: For the Nine Months Ended September 30, 2020 Unrealized (loss) 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 gain (loss) before reclassifications 3,053 662 (10,498) (6,783) Amounts reclassified from accumulated other comprehensive loss — — 1,796 1,796 Ending Balance $ — $ (146) $ (24,695) $ (24,841)

Accounts Receivable (Tables)

Accounts Receivable (Tables)	9 Months Ended
Accounts Receivable (Tables)	Sep. 30, 2020
Receivables [Abstract]
Schedule of Accounts Receivable and Allowance for Doubtful Accounts	At September 30, 2020 and December 31, 2019, accounts receivable (in thousands) consisted of the following: September 30, December 31, Trade receivables $ 133,127 $ 178,182 Less: Allowance for credit losses (6,677) (8,984) Net trade receivables 126,450 169,198 Other receivables (1) 47,377 13,040 Total accounts receivable $ 173,827 $ 182,238 (1) At September 30, 2020, other receivables included $42.3 million of refunds related to NOL carryback claims filed for various tax years in accordance with certain provisions of the CARES Act. At December 31, 2019, other receivables included $8.1 million of refundable alternative minimum tax credits. The following table reflects the change of the allowance for credit losses (in thousands) for the nine months ended September 30, 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 1,340 41 1,381 Write-offs (3,328) (360) (3,688) Ending balance, September 30, 2020 $ 5,652 $ 1,025 $ 6,677

Inventories (Tables)

Inventories (Tables)	9 Months Ended
Inventories (Tables)	Sep. 30, 2020
Inventory Disclosure [Abstract]
Schedule of Inventories	At September 30, 2020 and December 31, 2019, inventories (in thousands) consisted of the following: September 30, 2020 December 31, 2019 Supplies $ 43,331 $ 47,277 Raw materials and work in process 34,544 41,167 Finished goods 26,836 35,988 Total inventories $ 104,711 $ 124,432

Property, Plant and Mine Deve_2

Property, Plant and Mine Development (Tables)	9 Months Ended
Property, Plant and Mine Development (Tables)	Sep. 30, 2020
Property, Plant and Equipment [Abstract]
Schedule of Property, Plant and Mine Development	At September 30, 2020 and December 31, 2019, property, plant and mine development (in thousands) consisted of the following: September 30, December 31, Mining property and mine development $ 788,710 $ 794,899 Asset retirement cost 18,011 18,260 Land 55,281 57,082 Land improvements 75,878 73,203 Buildings 69,492 69,112 Machinery and equipment 1,179,002 1,152,898 Furniture and fixtures 4,071 4,068 Construction-in-progress 34,034 54,675 2,224,479 2,224,197 Accumulated depreciation, depletion, amortization and impairment charges (808,843) (706,610) Total property, plant and mine development, net $ 1,415,636 $ 1,517,587

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	9 Months Ended
Goodwill and Intangible Assets (Tables)	Sep. 30, 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 September 30, 2020 $ — $ 185,649 $ 185,649 (1) During the first quarter of 2020, an 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.
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: September 30, 2020 December 31, 2019 Gross Carrying Amount Accumulated Amortization Impairments Net Gross Carrying Amount Accumulated Amortization Impairments Net Technology and intellectual property $ 72,801 $ (19,278) $ — $ 53,523 $ 86,183 $ (17,080) $ — $ 69,103 Customer relationships 66,999 (21,980) — 45,019 68,599 (18,737) (1,240) 48,622 Total definite-lived intangible assets: $ 139,800 $ (41,258) $ — $ 98,542 $ 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: $ 205,890 $ (41,258) $ — $ 164,632 $ 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: September 30, 2020 December 31, 2019 Gross Carrying Amount Accumulated Amortization Impairments Net Gross Carrying Amount Accumulated Amortization Impairments Net Technology and intellectual property $ 72,801 $ (19,278) $ — $ 53,523 $ 86,183 $ (17,080) $ — $ 69,103 Customer relationships 66,999 (21,980) — 45,019 68,599 (18,737) (1,240) 48,622 Total definite-lived intangible assets: $ 139,800 $ (41,258) $ — $ 98,542 $ 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: $ 205,890 $ (41,258) $ — $ 164,632 $ 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 three months) $ 2,718 2021 10,866 2022 10,851 2023 10,846 2024 10,848

Debt (Tables)

Debt (Tables)	9 Months Ended
Debt (Tables)	Sep. 30, 2020
Debt Disclosure [Abstract]
Schedule of Debt	At September 30, 2020 and December 31, 2019, debt (in thousands) consisted of the following: September 30, December 31, Senior secured credit facility: Revolver expiring May 1, 2023 (4.19% at September 30, 2020 and 7.75% at December 31, 2019) $ 25,000 $ — Term Loan—final maturity May 1, 2025 (5.00% at September 30, 2020 and 5.81% at December 31, 2019) 1,238,000 1,247,600 Less: Unamortized original issue discount (4,634) (5,412) Less: Unamortized debt issuance cost (21,535) (25,390) Note payable secured by royalty interest 10,813 10,438 Insurance financing notes payable 5,573 5,055 Equipment notes payable — 87 Finance leases — 70 Total debt 1,253,217 1,232,448 Less: current portion (44,248) (18,463) Total long-term portion of debt $ 1,208,969 $ 1,213,985
Schedule of Contractual Maturities of Debt	At September 30, 2020, contractual maturities of our Term Loan (in thousands) are as follows: 2020 (remaining three months) $ 3,200 2021 12,800 2022 12,800 2023 12,800 2024 12,800 Thereafter 1,183,600 Total $ 1,238,000 2020 (remaining three months) $ 945 2021 367 2022 423 2023 487 2024 557 Thereafter 8,034 Total $ 10,813

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	9 Months Ended
Asset Retirement Obligations (Tables)	Sep. 30, 2020
Asset Retirement Obligation Disclosure [Abstract]
Schedule of Changes in Asset Retirement Obligations	Changes in the asset retirement obligations (in thousands) during the nine months ended September 30, 2020 and 2019 are as follows: Nine Months Ended 2020 2019 Beginning balance $ 25,825 $ 18,413 Accretion 1,098 1,138 Additions and revisions of estimates (890) 1,061 Ending balance $ 26,033 20,612

Derivative Instruments (Tables)

Derivative Instruments (Tables)	9 Months Ended
Derivative Instruments (Tables)	Sep. 30, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Estimated Fair Values of Derivative Instruments	The following table summarizes the fair values 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 September 30, 2020 and December 31, 2019. September 30, 2020 December 31, 2019 Maturity Contract/Notional Carrying Fair Maturity Date Contract/Notional Carrying Fair LIBOR (1) interest rate swap agreement 2020 $440 million $ — $ — 2020 $440 million $ (2,768) $ (2,768) LIBOR (1) interest rate swap agreement 2020 $200 million $ — $ — 2020 $200 million $ (1,259) $ (1,259)
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 nine months ended September 30, 2020 and 2019: Nine Months Ended 2020 2019 Deferred losses from derivatives in OCI, beginning of period $ (3,053) $ (1,621) Gain (loss) recognized in OCI from derivative instruments 3,053 (2,520) Deferred losses from derivatives in OCI, end of period $ — $ (4,141)

Equity-Based Compensation (Tabl

Equity-Based Compensation (Tables)	9 Months Ended
Equity-Based Compensation (Tables)	Sep. 30, 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 nine months ended September 30, 2020: Number of Weighted Aggregate Intrinsic Value Weighted Outstanding at December 31, 2019 826,658 $ 28.97 $ 11,557 4.1 years Granted — $ — $ — Exercised — $ — $ — Forfeited (443) $ 32.41 $ — Expired — $ — $ — Outstanding at September 30, 2020 826,215 $ 29.05 $ — 3.3 years Exercisable at September 30, 2020 826,215 $ 29.05 $ — 3.3 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 nine months ended September 30, 2020: Number of Shares Grant Date Weighted Unvested, December 31, 2019 1,020,248 $ 15.86 Granted 1,541,473 $ 4.13 Vested (490,414) $ 16.61 Forfeited (281,134) $ 10.54 Unvested, September 30, 2020 1,790,173 $ 6.45 The following table summarizes the status of, and changes in, our performance share unit awards during the nine months ended September 30, 2020: Number of Shares Grant Date Weighted Unvested, December 31, 2019 838,722 $ 18.00 Granted 1,020,161 $ 9.94 Vested — $ — Forfeited/Cancelled (341,221) $ 25.88 Unvested, September 30, 2020 1,517,662 $ 14.28

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
Commitments and Contingencies (Tables)	Sep. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Annual Commitments	Future Minimum Annual Commitments at September 30, 2020 (in thousands): Minimum Purchase Commitments 2020 (remaining three months) $ 1,864 2021 13,542 2022 10,328 2023 10,328 2024 7,020 Thereafter 10,147 Total future purchase commitments $ 53,229

Pension and Post-Retirement B_2

Pension and Post-Retirement Benefits (Tables)	9 Months Ended
Pension and Post-Retirement Benefits (Tables)	Sep. 30, 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 and nine months ended September 30, 2020 and 2019: Three Months Ended Nine Months Ended 2020 2019 2020 2019 Service cost $ 199 $ 323 $ 1,515 $ 1,065 Interest cost 356 1,503 2,349 4,813 Expected return on plan assets (531) (1,727) (3,394) (5,745) Net amortization and deferral 276 459 2,078 1,305 Net pension benefit costs $ 300 $ 558 $ 2,548 $ 1,438 Net post-retirement benefit cost (in thousands) consisted of the following for the three and nine months ended September 30, 2020 and 2019: Three Months Ended Nine Months Ended 2020 2019 2020 2019 Service cost $ 28 $ 20 $ 65 $ 67 Interest cost 235 182 426 572 Unrecognized net (gain)/loss — (7) — (7) Net post-retirement benefit costs $ 263 $ 195 $ 491 $ 632

Leases (Tables)

Leases (Tables)	9 Months Ended
Leases (Tables)	Sep. 30, 2020
Leases [Abstract]
Schedule of Supplemental Balance Sheet Information	Supplemental balance sheet information related to leases was as follows (in thousands, except lease term and discount rate): Leases Classification September 30, December 31, 2019 Assets Operating Operating lease right-of-use assets $ 41,265 $ 53,098 Total leased right-of-use assets $ 41,265 $ 53,098 Liabilities Current Operating Current portion of operating lease liabilities $ 30,887 $ 53,587 Non-current Operating Operating lease liabilities 76,827 117,964 Total lease liabilities $ 107,714 $ 171,551 Lease Term and Discount Rate Weighted average remaining lease term: Operating leases 5.2 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 (in thousands) were as follows: Lease Costs Classification Three Months Ended Three Months Ended Nine Months Ended Nine Months Ended Operating lease costs (1) Cost of sales $ 5,711 $ 21,787 $ 21,417 $ 69,547 Operating lease costs (2) Selling, general and administrative 415 1,044 1,420 3,281 Total $ 6,126 $ 22,831 $ 22,837 $ 72,828 (1) Included short-term operating lease costs of $0.3 million and $7.5 million for the three and nine months ended September 30, 2020, respectively. Included short-term operating lease costs of $4.0 million and $15.1 million for the three and nine months ended September 30, 2019, respectively. (2) Included short-term operating lease costs of $0.1 million and $0.3 million for the three and nine months ended September 30, 2020, respectively. Included short-term operating lease costs of $0.2 million and $0.6 million for the three and nine months ended September 30, 2019, respectively. Supplemental cash flow information (in thousands) related to leases was as follows: Nine Months Ended Nine Months Ended Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows for operating leases $ 51,859 $ 57,523 Right-of-use assets obtained in exchange for new lease liabilities: Operating leases $ 10,650 $ 229,557
Schedule of Maturity of Lease Liabilities	Maturities of lease liabilities (in thousands) as of September 30, 2020: Operating leases 2020 (remaining three months) $ 10,757 2021 32,226 2022 18,572 2023 15,676 2024 12,716 Thereafter 46,823 Total lease payments $ 136,770 Less: Interest 29,056 Total $ 107,714

Revenue (Tables)

Revenue (Tables)	9 Months Ended
Revenue (Tables)	Sep. 30, 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 and nine months ended September 30, 2020 and 2019 (in thousands): Three Months Ended Three Months Ended Category Oil & Gas Proppants Industrial & Specialty Products Total Sales Oil & Gas Proppants Industrial & Specialty Products Total Sales Product $ 49,508 $ 110,129 $ 159,637 $ 168,870 $ 119,107 $ 287,977 Service 16,835 — 16,835 73,837 — 73,837 Total Sales $ 66,343 $ 110,129 $ 176,472 $ 242,707 $ 119,107 $ 361,814 Nine Months Ended Nine Months Ended Category Oil & Gas Proppants Industrial & Specialty Products Total Sales Oil & Gas Proppants Industrial & Specialty Products Total Sales Product $ 217,943 $ 324,055 $ 541,998 $ 528,708 $ 359,170 $ 887,878 Service 76,610 — 76,610 247,540 — 247,540 Total Sales $ 294,553 $ 324,055 $ 618,608 $ 776,248 $ 359,170 $ 1,135,418
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 nine months ended September 30, 2020 and 2019 (in thousands): Unbilled Receivables September 30, 2020 September 30, 2019 Beginning Balance $ 144 $ 90 Reclassifications to billed receivables (350) (3,183) Revenues recognized in excess of period billings 1,226 3,893 Ending Balance $ 1,020 $ 800 Deferred Revenue September 30, 2020 September 30, 2019 Beginning Balance $ 50,634 $ 113,319 Revenues recognized from balances held at the beginning of the period (7,259) (24,241) Revenues deferred from period collections on unfulfilled performance obligations 4,782 12,225 Revenues recognized from period collections (3,815) (8,138) Ending Balance $ 44,342 $ 93,165
Schedule of Total Sales, Pre-tax Income and Net Income Related to Foreign Operations	The following table includes information related to our foreign operations for the three and nine months ended September 30, 2020 and 2019 (in thousands): Three Months Ended Three Months Ended Nine Months Ended Nine Months Ended Total Sales $ 22,084 $ 26,081 $ 65,948 $ 73,589 Pre-tax income $ 3,220 $ 3,491 $ 11,299 $ 10,309 Net income $ 2,544 $ 2,758 $ 8,927 $ 8,144

Segment Reporting (Tables)

Segment Reporting (Tables)	9 Months Ended
Segment Reporting (Tables)	Sep. 30, 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 and nine months ended September 30, 2020 and 2019: Three Months Ended Nine Months Ended 2020 2019 2020 2019 Sales: Oil & Gas Proppants $ 66,343 $ 242,707 $ 294,553 $ 776,248 Industrial & Specialty Products 110,129 119,107 324,055 359,170 Total sales 176,472 361,814 618,608 1,135,418 Segment contribution margin: Oil & Gas Proppants 31,478 50,557 90,540 180,601 Industrial & Specialty Products 42,353 44,397 120,821 139,103 Total segment contribution margin 73,831 94,954 211,361 319,704 Operating activities excluded from segment cost of sales (4,951) (16,773) (26,405) (59,617) Selling, general and administrative (27,216) (40,208) (96,394) (113,523) Depreciation, depletion and amortization (40,069) (47,126) (115,604) (136,625) Goodwill and other asset impairments (222) (130) (108,044) (130) Interest expense (19,274) (24,733) (63,730) (72,476) Other (expense) income, net, including interest income (409) 3,280 15,592 19,076 Income tax benefit 4,094 7,671 63,785 7,259 Net loss $ (14,216) $ (23,065) $ (119,439) $ (36,332) Less: Net loss attributable to non-controlling interest (254) (28) (778) (121) Net loss attributable to U.S. Silica Holdings, Inc. $ (13,962) $ (23,037) $ (118,661) $ (36,211)

Organization and Basis of Pre_2

Organization and Basis of Presentation (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2020USD ($)segment	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)
Organization And Nature Of Business
Number of reportable segments \| segment		2
Water rights intangibles acquired in VIE		$ 531	$ 3,493
Total assets of VIE		2,276,647		$ 2,553,234
Total liabilities of VIE		1,672,981		$ 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
Total assets of VIE		17,900
Total liabilities of VIE		100
Additional capital contribution paid to acquire interest in VIE		$ 200
Variable Interest Entity, Primary Beneficiary [Member] \| Water rights
Organization And Nature Of Business
Water rights intangibles acquired in VIE	$ 700

Earnings Per Share - Computatio

Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net loss attributable to U.S. Silica Holdings, Inc.	$ (13,962)	$ (23,037)	$ (118,661)	$ (36,211)
Denominator:
Weighted average shares outstanding (in shares)	73,688	73,328	73,601	73,223
Diluted effect of stock awards (in shares)	0	0	0	0
Weighted average shares outstanding assuming dilution (shares)	73,688	73,328	73,601	73,223
Loss per share attributable to U.S. Silica Holdings, Inc.:
Basic loss per share (in dollars per share)	$ (0.19)	$ (0.31)	$ (1.61)	$ (0.49)
Diluted loss per share (in dollars per share)	$ (0.19)	$ (0.31)	$ (1.61)	$ (0.49)

Earnings Per Share - Antidiluti

Earnings Per Share - Antidilutive Securities Excluded From Calculation of Diluted Earnings Per Share (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average outstanding stock options and restricted stock awards excluded (in shares)	348	91	173	191
Stock options excluded
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average outstanding stock options and restricted stock awards excluded (in shares)	826	700	826	716
Restricted stock and performance share unit awards excluded
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average outstanding stock options and restricted stock awards excluded (in shares)	2,667	265	4,103	280

Capital Structure and Accumul_3

Capital Structure and Accumulated Other Comprehensive Income (Loss) - Additional Information (Details) - USD ($)	3 Months Ended			9 Months Ended		28 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Dec. 31, 2019	May 31, 2018
Capital Structure And Accumulated Comprehensive Income (Loss)
Common stock authorized (in shares)	500,000,000			500,000,000		500,000,000	500,000,000
Common stock, par value (in dollars per share)	$ 0.01			$ 0.01		$ 0.01	$ 0.01
Common stock issued (in shares)	83,076,544			83,076,544		83,076,544	82,601,926
Common stock outstanding (in shares)	73,937,777			73,937,777		73,937,777	73,601,950
Dividends declared per share (in dollars per share)	$ 0	$ 0	$ 0.0625	$ 0.02	$ 0.1875
Preferred stock authorized (in shares)	10,000,000			10,000,000		10,000,000	10,000,000
Preferred stock, par value (in dollars per share)	$ 0.01			$ 0.01		$ 0.01	$ 0.01
Preferred stock issued (in shares)	0			0		0	0
Preferred stock outstanding (in shares)	0			0		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)				0		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			$ 126,500,000		$ 126,500,000

Capital Structure and Accumul_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

Capital Structure and Accumul_5

Capital Structure and Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	$ 716,580	$ 1,052,304
Other comprehensive gain (loss) before reclassifications	(6,783)
Amounts reclassified from accumulated other comprehensive loss	1,796
Ending Balance	603,666	1,004,399
Unrealized (loss) gain on cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(3,053)	(1,621)
Other comprehensive gain (loss) before reclassifications	3,053	(2,520)
Amounts reclassified from accumulated other comprehensive loss	0
Ending Balance	0	(4,141)
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(808)
Other comprehensive gain (loss) before reclassifications	662
Amounts reclassified from accumulated other comprehensive loss	0
Ending Balance	(146)
Pension and other post-retirement benefits liability
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(15,993)
Other comprehensive gain (loss) before reclassifications	(10,498)
Amounts reclassified from accumulated other comprehensive loss	1,796
Ending Balance	(24,695)
Total
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(19,854)	(15,020)
Ending Balance	$ (24,841)	$ (25,421)

Business Combinations (Details)

Business Combinations (Details) - Arrows Up, LLC - SandBox Logistics - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2020
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
Increase in accounts receivable	$ 100,000		$ 1,000,000
Decrease in inventory			3,300,000
Decrease to property, plant and equipment			100,000
Measurement period adjustment recorded as net decrease to initial bargain gain recognized			$ 2,400,000

Accounts Receivable (Details)

Accounts Receivable (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Receivables [Abstract]
Trade receivables	$ 133,127	$ 178,182
Less: Allowance for credit losses	(6,677)	(8,984)
Net trade receivables	126,450	169,198
Other receivables	47,377	13,040
Total accounts receivable	173,827	182,238
Refundable NOL carryback claims filed in accordance with CARES Act provisions	$ 42,300
Refundable alternative minimum tax credits		$ 8,100

Accounts Receivable - Allowance

Accounts Receivable - Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Allowance for Doubtful Accounts Receivable Roll Forward
Beginning balance, December 31, 2019	$ 8,984
Provision for credit losses	1,381	$ 3,082
Write-offs	(3,688)
Ending balance, September 30, 2020	6,677
Oil & Gas Proppants
Allowance for Doubtful Accounts Receivable Roll Forward
Beginning balance, December 31, 2019	7,640
Provision for credit losses	1,340
Write-offs	(3,328)
Ending balance, September 30, 2020	5,652
Industrial & Specialty Products
Allowance for Doubtful Accounts Receivable Roll Forward
Beginning balance, December 31, 2019	1,344
Provision for credit losses	41
Write-offs	(360)
Ending balance, September 30, 2020	$ 1,025

Accounts Receivable - Additiona

Accounts Receivable - Additional Information (Details) - Customer Concentration Risk	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Sales \| Ten Largest Customers
Concentration Risk [Line Items]
Concentration risk percentage	23.00%	43.00%	32.00%	42.00%
Sales \| Customer One
Concentration Risk [Line Items]
Concentration risk percentage		11.00%		12.00%
Trade Accounts Receivables \| Customer One
Concentration Risk [Line Items]
Concentration risk percentage			15.00%		12.00%

Inventories (Details)

Inventories (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Supplies	$ 43,331	$ 47,277
Raw materials and work in process	34,544	41,167
Finished goods	26,836	35,988
Total inventories	$ 104,711	$ 124,432

Inventories - Additional Inform

Inventories - Additional Information (Details) - USD ($)	3 Months Ended	9 Months Ended
Inventories - Additional Information (Details) - USD ($)	Sep. 30, 2020	Sep. 30, 2020
Oil & Gas Proppants \| COVID-19
Inventory [Line Items]
Impairment changes related to unused inventory at idled plants	$ 0	$ 6,700,000

Property, Plant and Mine Deve_3

Property, Plant and Mine Development (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Property, Plant and Equipment
Property, plant and mine development, gross	$ 2,224,479	$ 2,224,197
Accumulated depreciation, depletion, amortization and impairment charges	(808,843)	(706,610)
Total property, plant and mine development, net	1,415,636	1,517,587
Mining property and mine development
Property, Plant and Equipment
Property, plant and mine development, gross	788,710	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	55,281	57,082
Land improvements
Property, Plant and Equipment
Property, plant and mine development, gross	75,878	73,203
Buildings
Property, Plant and Equipment
Property, plant and mine development, gross	69,492	69,112
Machinery and equipment
Property, Plant and Equipment
Property, plant and mine development, gross	1,179,002	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	$ 34,034	$ 54,675

Property, Plant and Mine Deve_4

Property, Plant and Mine Development - Additional Information (Details)	Mar. 21, 2018USD ($)transload_facility	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)
Property, Plant and Equipment
Depreciation expense		$ 37,300,000	$ 44,000,000	$ 106,600,000	$ 127,300,000
Gain on sale of transload facilities				1,785,000	(58,000)
Land
Property, Plant and Equipment
Impairment recognized on assets classified as held for sale				0
Prepaid expenses and other current assets \| Land
Property, Plant and Equipment
Assets classified as held for sale		2,200,000		2,200,000
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_facility	3
Total consideration received on sale of transload facilities	$ 86,100,000
Liabilities assumed by buyer on sale of transload facilities	2,200,000
Cash consideration received on sale of transload facilities	83,900,000
Gain on sale of transload facilities	5,800,000
Consideration received allocated to asset retirement obligations liabilities of transload facilities	2,100,000
Equipment note assumed the buyer on sale of transload facilities	100,000
Consideration allocated to vendor incentives in sale of transload facilities	60,300,000
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		9,600,000		9,600,000
Oil & Gas Proppants
Property, Plant and Equipment
Impairment of property, plant and equipment				11,600,000
Oil & Gas Proppants \| COVID-19
Property, Plant and Equipment
Impairment of property, plant and equipment		$ 0
Mining property and mine development
Property, Plant and Equipment
Interest cost capitalized in property, plant and mine development				$ 33,000	$ 1,900,000
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	25,800,000
Net book value of transload facilities	$ 20,000,000

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Carrying Amount of Goodwill by Business Segment (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Mar. 31, 2020	Sep. 30, 2020
Goodwill [Roll Forward]
Balance at December 31, 2019	$ 273,524	$ 273,524
Balance at September 30, 2020		185,649
EPM
Goodwill [Roll Forward]
Impairment loss		(86,100)
EPM acquisition adjustment		(1,775)
Oil & Gas Proppants Segment
Goodwill [Roll Forward]
Balance at December 31, 2019	86,100	86,100
Balance at September 30, 2020		0
Oil & Gas Proppants Segment \| EPM
Goodwill [Roll Forward]
Impairment loss		(86,100)
EPM acquisition adjustment		0
Industrial & Specialty Products Segment
Goodwill [Roll Forward]
Balance at December 31, 2019	187,424	187,424
Balance at September 30, 2020		185,649
Industrial & Specialty Products Segment \| EPM
Goodwill [Roll Forward]
Impairment loss		0
EPM acquisition adjustment	$ (1,800)	$ (1,775)

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Carrying Amount of Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 139,800	$ 154,782
Accumulated Amortization	(41,258)	(35,817)
Impairments	0	(1,240)
Net	98,542	117,725
Total Intangible Assets
Gross Carrying Amount	205,890	220,872
Accumulated Amortization	(41,258)	(35,817)
Impairments	0	(1,240)
Net	164,632	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	72,801	86,183
Accumulated Amortization	(19,278)	(17,080)
Impairments	0	0
Net	53,523	69,103
Total Intangible Assets
Accumulated Amortization	(19,278)	(17,080)
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	66,999	68,599
Accumulated Amortization	(21,980)	(18,737)
Impairments	0	(1,240)
Net	45,019	48,622
Total Intangible Assets
Accumulated Amortization	$ (21,980)	$ (18,737)

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Additional Information (Details) - USD ($)	3 Months Ended				6 Months Ended	9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2020	Sep. 30, 2019
Finite-Lived Intangible Assets [Line Items]
Amortization expense of intangibles	$ 2,500,000			$ 2,700,000		$ 7,900,000	$ 8,100,000
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
Oil & Gas Proppants
Finite-Lived Intangible Assets [Line Items]
Capitalized legal fees expensed due to unsuccessful defense of patent		$ 11,800,000
Oil & Gas Proppants \| COVID-19
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment			$ 86,100,000		$ 0

Goodwill and Intangible Asset_5

Goodwill and Intangible Assets - Estimated Amortization Expense Related to Definite-Lived Intangible Assets (Details) $ in Thousands	Sep. 30, 2020USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2020 (remaining three months)	$ 2,718
2021	10,866
2022	10,851
2023	10,846
2024	$ 10,848

Debt (Details)

Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Line of Credit Facility
Less: Unamortized original issue discount	$ (4,634)	$ (5,412)
Less: Unamortized debt issuance cost	(21,535)	(25,390)
Finance leases	0	70
Total debt	1,253,217	1,232,448
Less: current portion	(44,248)	(18,463)
Total long-term portion of debt	1,208,969	1,213,985
Notes Payable \| Insurance financing notes payable
Line of Credit Facility
Short-term debt	5,573	5,055
Notes Payable \| Note payable secured by royalty interest
Line of Credit Facility
Long-term debt	10,813	10,438
Notes Payable \| Equipment notes payable
Line of Credit Facility
Long-term debt	$ 0	$ 87
Revolving Line-of-Credit \| Revolver
Line of Credit Facility
Interest rate	4.19%	7.75%
Long-term debt	$ 25,000	$ 0
Senior Secured Credit Facility \| Term Loan
Line of Credit Facility
Interest rate	5.00%	5.81%
Long-term debt	$ 1,238,000	$ 1,247,600

Debt - Additional Information (

Debt - Additional Information (Details)	Oct. 01, 2020USD ($)payment	May 01, 2018USD ($)	Sep. 30, 2020USD ($)	Dec. 31, 2019USD ($)	Aug. 16, 2016USD ($)
Insurance financing notes payable \| Notes Payable
Debt Instrument [Line Items]
Debt interest rate percentage			3.00%
Debt term			9 months
Notes payable balance			$ 5,573,000	$ 5,055,000
Revolving Line-of-Credit \| Revolver
Debt Instrument [Line Items]
Available borrowing base			100,000,000
Amount drawn from borrowing base			25,000,000
Amount available under the line of credit			$ 49,600,000
Current consolidated leverage ratio			5.85
Amount available under the line of credit without consent of the lenders			$ 30,000,000
Letter of Credit \| Revolver
Debt Instrument [Line Items]
Amount allocated for letters of credit			25,400,000
Senior Secured Credit Facility
Debt Instrument [Line Items]
Debt issued		$ 1,380,000,000
Capitalized debt issuance costs and original issue discount		38,700,000
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]
Debt issued		$ 100,000,000
Credit facility consolidated total net leverage ratio		3.75
Net leverage ratio, credit facility threshold percentage		30.00%
Notes Payable \| Note payable secured by royalty interest
Debt Instrument [Line Items]
Annual minimum payments			500,000
Estimated fair value of note payable					$ 22,500,000
Notes payable amount			10,800,000
Future royalties accrued			$ 0
Notes Payable \| Note payable secured by royalty interest \| Subsequent Event
Debt Instrument [Line Items]
One-time settlement payment of notes payable \| payment	1
Settlement payment of notes payable	$ 2,550,000
Notes Payable \| Note payable secured by royalty interest \| Measurement Input, Discount Rate
Debt Instrument [Line Items]
Fair value discount rate			0.14		0.14

Debt - Contractual Maturities o

Debt - Contractual Maturities of Senior Secured Credit Facility (Details) - Senior Secured Credit Facility - Term Loan - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
2020 (remaining three months)	$ 3,200
2021	12,800
2022	12,800
2023	12,800
2024	12,800
Thereafter	1,183,600
Total	$ 1,238,000	$ 1,247,600

Debt - Contractual Maturities_2

Debt - Contractual Maturities of Note Payable Secured by Royalty Interest (Details) - Notes Payable - Note payable secured by royalty interest - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
2020 (remaining three months)	$ 945
2021	367
2022	423
2023	487
2024	557
Thereafter	8,034
Total	$ 10,813	$ 10,438

Asset Retirement Obligations (D

Asset Retirement Obligations (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Asset Retirement Obligation Disclosure [Abstract]
Other long-term liabilities related to asset retirement obligation	$ 26,000		$ 20,600
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance	25,825	$ 18,413
Accretion	1,098	1,138
Additions and revisions of estimates	(890)	1,061
Ending balance	$ 26,033	$ 20,612

Fair Value Accounting (Details)

Fair Value Accounting (Details) - Interest rate swap	Sep. 30, 2020USD ($)derivative	Jul. 31, 2020USD ($)derivative
Fair Value [Line Items]
Number of interest rate swaps agreements \| derivative	2	2
Fair value of interest rate swap agreements \| $	$ 0	$ 0

Derivative Instruments - Additi

Derivative Instruments - Additional Information (Details)	9 Months Ended
Derivative Instruments - Additional Information (Details)	Sep. 30, 2020USD ($)derivative	Jul. 31, 2020USD ($)derivative	Dec. 31, 2019USD ($)derivative
Interest rate swap
Derivative [Line Items]
Number of interest rate swaps agreements \| derivative	2	2
Fair value of interest rate swap agreements	$ 0	$ 0
Ineffectiveness for interest rate swap derivatives	$ 0
Interest rate swap \| Cash Flow Hedges
Derivative [Line Items]
Number of interest rate swaps agreements \| derivative	2		2
Interest rate swap - notional amount $440 million
Derivative [Line Items]
Fair value of interest rate swap agreements	$ 0		$ 2,768,000
Interest rate swap - notional amount $440 million \| Cash Flow Hedges \| Other long-term liabilities
Derivative [Line Items]
Fair value of interest rate swap agreements	0		2,800,000
Interest rate swap - notional amount $200 million
Derivative [Line Items]
Fair value of interest rate swap agreements	0		1,259,000
Interest rate swap - notional amount $200 million \| Cash Flow Hedges \| Other long-term liabilities
Derivative [Line Items]
Fair value of interest rate swap agreements	$ 0		$ 1,300,000

Derivative Instruments - Estima

Derivative Instruments - Estimated Fair Values of Derivative Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Interest rate swap - notional amount $440 million
Derivative Instruments, Gain (Loss)
Contract/Notional Amount	$ 440,000	$ 440,000
Carrying Amount	0	(2,768)
Fair Value	$ 0	$ (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	0	(1,259)
Fair Value	$ 0	$ (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%

Derivative Instruments - Effect

Derivative Instruments - Effects of Derivatives Instruments in Combined Statements of Operations and Comprehensive Income (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	$ 716,580	$ 1,052,304
Gain (loss) recognized in OCI from derivative instruments	(6,783)
Ending Balance	603,666	1,004,399
Unrealized (loss) gain on cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(3,053)	(1,621)
Gain (loss) recognized in OCI from derivative instruments	3,053	(2,520)
Ending Balance	$ 0	$ (4,141)

Equity-Based Compensation - Add

Equity-Based Compensation - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants of stock options (in shares)	0	0	0	0
Stock options exercised (in shares)	0	0	0	10,000
Intrinsic value of stock options exercised				$ 12,000
Cash received from options exercised			$ 0	128,000
Tax benefit realized from stock options exercised				3,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense related to stock options	$ 0	$ 0	$ 0	$ 0
Restricted Stock and Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)	49,696	34,790	1,541,473	791,903
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized equity-based compensation	$ 2,700,000	$ 2,000,000	$ 6,600,000	$ 6,400,000
Unrecognized compensation expense related to awards	$ 8,000,000		$ 8,000,000
Recognized weighted-average period			1 year 8 months 12 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)	0		335,039
Recognized equity-based compensation	$ 100,000		$ 200,000
Unrecognized compensation expense related to awards	$ 700,000		$ 700,000
Recognized weighted-average period			2 years 4 months 24 days
Awards forfeited and partially vested (in shares)	58,246		58,246
Award vesting period			3 years
Performance Share Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)	0	0	1,020,161	607,130
Recognized equity-based compensation	$ 2,700,000	$ 1,800,000	$ 5,700,000	$ 4,300,000
Unrecognized compensation expense related to awards	10,800,000		$ 10,800,000
Recognized weighted-average period			1 year 10 months 24 days
Performance Shares to be Settled in Cash
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized equity-based compensation			$ 700,000
Unrecognized compensation expense related to awards	$ 1,500,000		$ 1,500,000
Recognized weighted-average period			2 years 4 months 24 days
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)	3,787,156		3,787,156

Equity-Based Compensation - Sto

Equity-Based Compensation - Stock Options (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Number of Shares
Outstanding at December 31, 2019 (in shares)			826,658
Granted (in shares)	0	0	0	0
Exercised (in shares)	0	0	0	(10,000)
Forfeited (in shares)			(443)
Expired (in shares)			0
Outstanding at September 30, 2020 (in shares)	826,215		826,215		826,658
Exercisable at September 30, 2020 (in shares)	826,215		826,215
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)			32.41
Expired (in dollars per share)			0
Outstanding at September 30, 2020 (in dollars per share)	$ 29.05		29.05		$ 28.97
Exercisable at September 30, 2020 (in dollars per share)	$ 29.05		$ 29.05
Aggregate Intrinsic Value
Outstanding	$ 0		$ 0		$ 11,557
Exercisable at September 30, 2020	$ 0		$ 0
Weighted Average Remaining Contractual Term in Years
Outstanding at September 30, 2020			3 years 3 months 18 days		4 years 1 month 6 days
Exercisable at September 30, 2020			3 years 3 months 18 days

Equity-Based Compensation - Res

Equity-Based Compensation - Restricted Stock and Restricted Stock Units Awards (Details) - Restricted Stock and Restricted Stock Units - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Number of Shares
Unvested, December 31, 2019 (in shares)			1,020,248
Granted (in shares)	49,696	34,790	1,541,473	791,903
Vested (in shares)			(490,414)
Forfeited (in shares)			(281,134)
Unvested, September 30, 2020 (in shares)	1,790,173		1,790,173
Grant Date Weighted Average Fair Value
Unvested, December 31, 2019 (in dollars per share)			$ 15.86
Granted (in dollars per share)			4.13
Vested (in dollars per share)			16.61
Forfeited (in dollars per share)			10.54
Unvested, September 30, 2020 (in dollars per share)	$ 6.45		$ 6.45

Equity-Based Compensation - Per

Equity-Based Compensation - Performance Share Awards (Details) - Performance Share Units - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Number of Shares
Unvested, December 31, 2019 (in shares)			838,722
Granted (in shares)	0	0	1,020,161	607,130
Vested (in shares)			0
Forfeited/Cancelled (in shares)			(341,221)
Unvested, September 30, 2020 (in shares)	1,517,662		1,517,662
Grant Date Weighted Average Fair Value
Unvested, December 31, 2019 (in dollars per share)			$ 18
Granted (in dollars per share)			9.94
Vested (in dollars per share)			0
Forfeited/Cancelled (in dollars per share)			25.88
Unvested, September 30, 2020 (in dollars per share)	$ 14.28		$ 14.28

Commitments and Contingencies -

Commitments and Contingencies - Future Minimum Annual Commitments (Details) $ in Thousands	Sep. 30, 2020USD ($)
Minimum Purchase Commitments
2020 (remaining three months)	$ 1,864
2021	13,542
2022	10,328
2023	10,328
2024	7,020
Thereafter	10,147
Total future purchase commitments	$ 53,229

Commitments and Contingencies_2

Commitments and Contingencies - Additional Information (Details)	May 17, 2017USD ($)	Sep. 30, 2020USD ($)claim	Dec. 31, 2019USD ($)
Loss Contingencies
Purchased reserves	$ 94,400,000
Number of new claims \| claim		0
Surety Bonds
Loss Contingencies
Surety bonds outstanding		$ 35,100,000
Reclamation Bonds
Loss Contingencies
Surety bonds outstanding		31,100,000
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	$ 900,000
Pending Litigation
Loss Contingencies
Number of pending claims \| claim		54

Pension and Post-Retirement B_3

Pension and Post-Retirement Benefits - Net Pension and Post-Retirement Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Pension Benefits
Pension Plans, Postretirement and Other Employee Benefits
Service cost	$ 199	$ 323	$ 1,515	$ 1,065
Interest cost	356	1,503	2,349	4,813
Expected return on plan assets	(531)	(1,727)	(3,394)	(5,745)
Net amortization and deferral	276	459	2,078	1,305
Net benefit costs	300	558	2,548	1,438
Post-retirement Benefits
Pension Plans, Postretirement and Other Employee Benefits
Service cost	28	20	65	67
Interest cost	235	182	426	572
Unrecognized net (gain)/loss	0	(7)	0	(7)
Net benefit costs	$ 263	$ 195	$ 491	$ 632

Pension and Post-Retirement B_4

Pension and Post-Retirement Benefits - Additional Information (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)plan	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)plan	Sep. 30, 2019USD ($)
Pension Plans, Postretirement and Other Employee Benefits
Number of multiemployer defined benefit plans \| plan	3		3
Percentage of contributions to individual multiemployer plan (less than)	5.00%	5.00%	5.00%	5.00%
Company contributions to qualified pension plans	$ 0.6	$ 1.5	$ 2.8	$ 4.8
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	2.2	$ 2.1	$ 4.2	$ 3.8
Expected contributions to the plans for the 2020 fiscal year	5.1		5.1
Post-retirement Medical Plan
Pension Plans, Postretirement and Other Employee Benefits
Expected contributions to the plans for the 2020 fiscal year	$ 1.4		$ 1.4

Leases - Additional Information

Leases - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Sep. 30, 2019
Lessee, Lease, Description [Line Items]
Gain on lease concessions received from lessors recognized as operating income through costs of good sold		$ 24,415	$ 0
COVID-19
Lessee, Lease, Description [Line Items]
Decrease in ROU assets due to concessions received from lessors	$ 400	900
Decrease in lease liabilities due to concessions received from lessors	20,900	25,000
Gain on lease concessions received from lessors recognized as operating income through costs of good sold	20,500	24,400
Oil & Gas Proppants \| COVID-19
Lessee, Lease, Description [Line Items]
Lease impairment charges	$ 200	$ 3,400
Minimum
Lessee, Lease, Description [Line Items]
Remaining term of lease contracts		1 year
Maximum
Lessee, Lease, Description [Line Items]
Remaining term of lease contracts		20 years

Leases - Supplemental Balance S

Leases - Supplemental Balance Sheet Information (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease right-of-use assets	$ 41,265	$ 53,098
Current portion of operating lease liabilities	30,887	53,587
Non-current operating lease liabilities	76,827	117,964
Total lease liabilities	$ 107,714	$ 171,551
Operating leases, weighted average remaining lease term	5 years 2 months 12 days	4 years 6 months
Operating leases, weighted average discount rate	5.70%	5.70%

Leases - Components of Lease Ex

Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Lessee, Lease, Description [Line Items]
Lease costs	$ 6,126	$ 22,831	$ 22,837	$ 72,828
Cost of sales
Lessee, Lease, Description [Line Items]
Lease costs	5,711	21,787	21,417	69,547
Short-term operating lease costs	300	7,500	4,000	15,100
Selling, general and administrative
Lessee, Lease, Description [Line Items]
Lease costs	415	1,044	1,420	3,281
Short-term operating lease costs	$ 100	$ 300	$ 200	$ 600

Leases - Supplemental Cash Flow

Leases - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Leases [Abstract]
Cash paid for amounts included in the measurement of lease liabilities, operating leases	$ 51,859	$ 57,523
Right-of-use assets obtained in exchange for new lease liabilities, operating leases	$ 10,650	$ 229,557

Leases - Maturities of Lease Li

Leases - Maturities of Lease Liabilities (Details) $ in Thousands	Sep. 30, 2020USD ($)
Leases [Abstract]
2020 (remaining three months)	$ 10,757
2021	32,226
2022	18,572
2023	15,676
2024	12,716
Thereafter	46,823
Total lease payments	136,770
Less: Interest	29,056
Total	$ 107,714

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Income Taxes (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Tax Contingency [Line Items]
Income tax benefits	$ 4,094	$ 7,671	$ 63,785	$ 7,259
Effective tax rate	22.00%	25.00%	35.00%	17.00%
Effective tax rate without the effects of discrete tax items	26.00%	27.00%	24.00%	29.00%
Tax expense related equity compensation	$ 300	$ 100	$ 1,700	$ 4,500
COVID-19
Income Tax Contingency [Line Items]
Tax refunds received			36,600
CARES Act, refundable NOL credits	26,300		26,300
CARES Act deferred income tax benefit			22,300
CARES Act, refundable ATM credits	$ 16,000		$ 16,000

Revenue - Sales by Major Source

Revenue - Sales by Major Source (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Total Sales	$ 176,472	$ 361,814	$ 618,608	$ 1,135,418
Oil & Gas Proppants
Disaggregation of Revenue [Line Items]
Total Sales	66,343	242,707	294,553	776,248
Industrial & Specialty Products
Disaggregation of Revenue [Line Items]
Total Sales	110,129	119,107	324,055	359,170
Product
Disaggregation of Revenue [Line Items]
Total Sales	159,637	287,977	541,998	887,878
Product \| Oil & Gas Proppants
Disaggregation of Revenue [Line Items]
Total Sales	49,508	168,870	217,943	528,708
Product \| Industrial & Specialty Products
Disaggregation of Revenue [Line Items]
Total Sales	110,129	119,107	324,055	359,170
Service
Disaggregation of Revenue [Line Items]
Total Sales	16,835	73,837	76,610	247,540
Service \| Oil & Gas Proppants
Disaggregation of Revenue [Line Items]
Total Sales	16,835	73,837	76,610	247,540
Service \| Industrial & Specialty Products
Disaggregation of Revenue [Line Items]
Total Sales	$ 0	$ 0	$ 0	$ 0

Revenue - Changes in Contract A

Revenue - Changes in Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Unbilled Receivables
Beginning Balance	$ 144	$ 90
Reclassifications to billed receivables	(350)	(3,183)
Revenues recognized in excess of period billings	1,226	3,893
Ending Balance	1,020	800
Deferred Revenue
Beginning Balance	50,634	113,319
Revenues recognized from balances held at the beginning of the period	(7,259)	(24,241)
Revenues deferred from period collections on unfulfilled performance obligations	4,782	12,225
Revenues recognized from period collections	(3,815)	(8,138)
Ending Balance	$ 44,342	$ 93,165

Revenue - Additional Informatio

Revenue - Additional Information (Details) $ in Millions	3 Months Ended	9 Months Ended
Revenue - Additional Information (Details) $ in Millions	Sep. 30, 2020USD ($)	Sep. 30, 2020USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue recognized on variable consideration from shortfall penalties	$ 2.2	$ 19.8
Revenue recognized on variable consideration shortfall penalties included in deferred revenue	$ 1.5	$ 3
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining duration period of expected satisfaction of performance obligations (less than)	1 year	1 year

Revenue - Foreign Operations (D

Revenue - Foreign Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Total sales	$ 176,472	$ 361,814	$ 618,608	$ 1,135,418
Pre-tax income	(18,310)	(30,736)	(183,224)	(43,591)
Net income	(13,962)	(23,037)	(118,661)	(36,211)
Assets	2,276,647		2,276,647		$ 2,553,234
Foreign Operations
Disaggregation of Revenue [Line Items]
Total sales	22,084	26,081	65,948	73,589
Pre-tax income	3,220	3,491	11,299	10,309
Net income	2,544	2,758	8,927	8,144
Assets	$ 32,800	$ 28,400	$ 32,800	$ 28,400

Segment Reporting - Additional

Segment Reporting - Additional Information (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)productsegment	Dec. 31, 2019USD ($)
Segment Reporting Information
Number of reportable segments \| segment	2
Number of product types (over 400) \| product	400
Goodwill	$ 185,649	$ 273,524
Oil & Gas Proppants
Segment Reporting Information
Goodwill	0	86,100
Industrial & Specialty Products
Segment Reporting Information
Goodwill	$ 185,600	$ 187,400

Segment Reporting - Sales and S

Segment Reporting - Sales and Segment Contribution Margin for Reporting Segments and Other Operating Results (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information
Total sales	$ 176,472	$ 361,814	$ 618,608	$ 1,135,418
Total segment contribution margin	73,831	94,954	211,361	319,704
Operating activities excluded from segment cost of sales	(4,951)	(16,773)	(26,405)	(59,617)
Selling, general and administrative	(27,216)	(40,208)	(96,394)	(113,523)
Depreciation, depletion and amortization	(40,069)	(47,126)	(115,604)	(136,625)
Goodwill and other asset impairments	(222)	(130)	(108,044)	(130)
Interest expense	(19,274)	(24,733)	(63,730)	(72,476)
Other (expense) income, net, including interest income	(409)	3,280	15,592	19,076
Income tax benefit	4,094	7,671	63,785	7,259
Net loss	(14,216)	(23,065)	(119,439)	(36,332)
Less: Net loss attributable to non-controlling interest	(254)	(28)	(778)	(121)
Net loss attributable to U.S. Silica Holdings, Inc.	(13,962)	(23,037)	(118,661)	(36,211)
Oil & Gas Proppants
Segment Reporting Information
Total sales	66,343	242,707	294,553	776,248
Total segment contribution margin	31,478	50,557	90,540	180,601
Industrial & Specialty Products
Segment Reporting Information
Total sales	110,129	119,107	324,055	359,170
Total segment contribution margin	$ 42,353	$ 44,397	$ 120,821	$ 139,103