U.S. Silica (SLCA) 10-K 25 Feb 22 2021 FY Annual report Financial data

Cover

Cover - USD ($)	12 Months Ended
	Dec. 31, 2021	Feb. 18, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2021
Current Fiscal Year End Date	--12-31
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, par value $0.01 per share
Trading Symbol	SLCA
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
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
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 814,478,897
Entity Common Stock, Shares Outstanding		75,028,013
Documents Incorporated by Reference	Certain sections of the Proxy Statement for the 2022 Annual Meeting of Shareholders for U.S. Silica Holdings, Inc. (the “2022 Proxy Statement”) are incorporated by reference in Part III of this Annual Report on Form 10-K where indicated.
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Entity Central Index Key	0001524741

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2021
Audit Information [Abstract]
Auditor Firm ID	248
Auditor Name	GRANT THORNTON LLP
Auditor Location	Houston, Texas

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current Assets:
Cash and cash equivalents	$ 239,425	$ 150,920
Accounts receivable, net	202,759	206,934
Inventories, net	115,713	104,684
Prepaid expenses and other current assets	18,018	23,147
Income tax deposits	0	628
Total current assets	575,915	486,313
Property, plant and mine development, net	1,258,646	1,368,092
Lease right-of-use assets	42,241	37,469
Goodwill	185,649	185,649
Intangible assets, net	150,054	159,582
Other assets	7,095	9,842
Total assets	2,219,600	2,246,947
Current Liabilities:
Accounts payable and accrued expenses	167,670	121,920
Current portion of operating lease liabilities	14,469	17,388
Current portion of long-term debt	18,285	42,042
Current portion of deferred revenue	4,247	13,545
Income tax payable	1,200	0
Total current liabilities	205,871	194,895
Long-term debt, net	1,193,135	1,197,660
Deferred revenue	16,494	20,147
Liability for pension and other post-retirement benefits	32,935	48,169
Deferred income taxes, net	44,774	49,386
Operating lease liabilities	75,130	76,361
Other long-term obligations	37,178	33,538
Total liabilities	1,605,517	1,620,156
Commitments and Contingencies (Note O)
Stockholders’ Equity:
Preferred stock, $0.01 par value, 10,000,000 shares authorized; zero issued and outstanding at December 31, 2021 and 2020	0	0
Common stock, $0.01 par value, 500,000,000 shares authorized; 84,746,194 issued and 75,033,352 outstanding at December 31, 2021; 83,143,176 issued and 73,986,566 outstanding at December 31, 2020	845	827
Additional paid-in capital	1,218,575	1,200,023
Retained deficit	(429,260)	(395,496)
Treasury stock, at cost, 9,712,842 and 9,156,610 shares at December 31, 2021 and 2020, respectively	(186,294)	(181,615)
Accumulated other comprehensive income (loss)	349	(8,479)
Total U.S. Silica Holdings, Inc. stockholders’ equity	604,215	615,260
Non-controlling interest	9,868	11,531
Total stockholders' equity	614,083	626,791
Total liabilities and stockholders’ equity	$ 2,219,600	$ 2,246,947

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock authorized (shares)	10,000,000	10,000,000
Preferred stock issued (shares)	0	0
Preferred stock outstanding (shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock authorized (shares)	500,000,000	500,000,000
Common stock issued (shares)	84,746,194	83,143,176
Common stock outstanding (shares)	75,033,352	73,986,566
Treasury stock, at cost (shares)	9,712,842	9,156,610

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Sales:
Total sales	$ 1,103,879	$ 845,885	$ 1,474,477
Cost of sales (excluding depreciation, depletion and amortization):
Total cost of sales (excluding depreciation, depletion and amortization)	794,983	575,070	1,133,293
Operating expenses:
Selling, general and administrative	119,628	124,171	150,848
Depreciation, depletion and amortization	161,131	155,568	179,444
Goodwill and other asset impairments	202	110,688	363,847
Total operating expenses	280,961	390,427	694,139
Operating income (loss)	27,935	(119,612)	(352,955)
Other (expense) income:
Interest expense	(71,157)	(79,885)	(95,472)
Other income, net, including interest income	6,146	24,350	19,519
Total other expense	(65,011)	(55,535)	(75,953)
Loss before income taxes	(37,076)	(175,147)	(428,908)
Income tax benefit	2,755	60,025	99,151
Net loss	(34,321)	(115,122)	(329,757)
Less: Net loss attributable to non-controlling interest	(560)	(1,028)	(675)
Net loss attributable to U.S. Silica Holdings, Inc.	$ (33,761)	$ (114,094)	$ (329,082)
Loss per share attributable to U.S. Silica Holdings, Inc.:
Basic (in dollars per share)	$ (0.45)	$ (1.55)	$ (4.49)
Diluted (in dollars per share)	$ (0.45)	$ (1.55)	$ (4.49)
Weighted average shares outstanding:
Basic (shares)	74,350	73,634	73,253
Diluted (shares)	74,350	73,634	73,253
Dividends declared per share (in dollars per share)	$ 0	$ 0.02	$ 0.25
Product
Sales:
Total sales	$ 896,203	$ 732,187	$ 1,168,472
Cost of sales (excluding depreciation, depletion and amortization):
Total cost of sales (excluding depreciation, depletion and amortization)	633,857	486,982	900,091
Service
Sales:
Total sales	207,676	113,698	306,005
Cost of sales (excluding depreciation, depletion and amortization):
Total cost of sales (excluding depreciation, depletion and amortization)	$ 161,126	$ 88,088	$ 233,202

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Net loss	$ (34,321)	$ (115,122)	$ (329,757)
Other comprehensive (loss) income:
Unrealized gain (loss) on derivatives (net of tax of $—, $973, and $(456) for 2021, 2020, and 2019, respectively)	0	3,053	(1,432)
Foreign currency translation adjustment (net of tax of $(309), $444, and $(60) for 2021, 2020 and 2019, respectively)	(1,000)	1,391	(188)
Pension and other post-retirement benefits liability adjustments (net of tax of $3,131, $2,207, and $(1,024) for 2021, 2020 and 2019, respectively)	9,828	6,931	(3,214)
Comprehensive loss	(25,493)	(103,747)	(334,591)
Less: Comprehensive loss attributable to non-controlling interest	(560)	(1,028)	(675)
Comprehensive loss attributable to U.S. Silica Holdings, Inc.	$ (24,933)	$ (102,719)	$ (333,916)

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Tax expense (benefit) on unrealized gain (loss) on derivatives	$ 0	$ 973	$ (456)
Tax expense (benefit) on foreign currency translation adjustment	(309)	444	(60)
Tax (expense) benefit on pension and other post-retirement benefits liability adjustment	$ 3,131	$ 2,207	$ (1,024)

Consolidated Statements of Stoc

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) Income	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	(329,757)	(329,082)				(329,082)		(675)
Unrealized gain (loss) on derivatives	(1,432)	(1,432)					(1,432)
Foreign currency translation adjustment	(188)	(188)					(188)
Pension and post-retirement liability	(3,214)	(3,214)					(3,214)
Cash dividend declared	(18,728)	(18,728)				(18,728)
Contributions from non-controlling interest	4,554							4,554
Common stock-based compensation plans activity:
Equity-based compensation	15,906	15,906			15,906
Proceeds from options exercised	128	128		296	(168)
Shares withheld for tax payments related to vested restricted stock and stock units	(2,993)	(2,993)	5	(2,993)	(5)
Ending Balance at Dec. 31, 2019	716,580	705,217	823	(180,912)	1,185,116	(279,956)	(19,854)	11,363
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(115,122)	(114,094)				(114,094)		(1,028)
Unrealized gain (loss) on derivatives	3,053	3,053					3,053
Foreign currency translation adjustment	1,391	1,391					1,391
Pension and post-retirement liability	6,931	6,931					6,931
Cash dividend declared	(1,446)	(1,446)				(1,446)
Contributions from non-controlling interest	1,196							1,196
Common stock-based compensation plans activity:
Equity-based compensation	14,911	14,911			14,911
Shares withheld for tax payments related to vested restricted stock and stock units	(703)	(703)	4	(703)	(4)
Ending Balance at Dec. 31, 2020	626,791	615,260	827	(181,615)	1,200,023	(395,496)	(8,479)	11,531
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(34,321)	(33,761)				(33,761)		(560)
Unrealized gain (loss) on derivatives	0
Foreign currency translation adjustment	(1,000)	(1,000)					(1,000)
Pension and post-retirement liability	9,828	9,828					9,828
Cash dividend declared	(3)	(3)				(3)
Distributions to non-controlling interest	(1,103)							(1,103)
Common stock-based compensation plans activity:
Equity-based compensation	18,809	18,809			18,809
Proceeds from options exercised	105	105		344	(239)
Shares withheld for tax payments related to vested restricted stock and stock units	(5,023)	(5,023)	18	(5,023)	(18)
Ending Balance at Dec. 31, 2021	$ 614,083	$ 604,215	$ 845	$ (186,294)	$ 1,218,575	$ (429,260)	$ 349	$ 9,868

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Stockholders' Equity [Abstract]
Cash dividend declared (in dollars per share)	$ 0	$ 0.02	$ 0.25

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating activities:
Net loss	$ (34,321)	$ (115,122)	$ (329,757)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation, depletion and amortization	161,131	155,568	179,444
Goodwill and other asset impairments	202	110,688	363,847
Debt issuance amortization	5,059	5,131	5,597
Original issue discount amortization	1,026	1,036	1,053
Gain on valuation change of royalty note payable	0	(8,263)	(16,854)
Inventory step-up adjustments	0	0	22,373
Deferred income taxes	(7,493)	(61,805)	(101,682)
Deferred revenue	(18,158)	(23,569)	(74,910)
(Gain) loss on disposal of property, plant and equipment	(131)	(2,597)	1,573
Equity-based compensation	18,809	14,911	15,906
Allowance for credit losses, net of recoveries	(455)	1,510	3,466
Gain on remeasurement of leases	0	(24,056)	0
Other	28,632	23,146	(12,042)
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable	5,026	48,441	33,837
Inventories	(11,029)	15,245	11,182
Prepaid expenses and other current assets	12,371	980	12,310
Income taxes	1,828	(153)	1,725
Accounts payable and accrued expenses	48,709	(86,734)	21,024
Short-term and long-term obligations-vendor incentives	0	0	4,021
Operating lease liabilities	(24,451)	(62,140)	(75,352)
Liability for pension and other post-retirement benefits	(15,341)	(11,941)	2,734
Other noncurrent assets and liabilities	(2,067)	16,321	78,314
Net cash provided by (used in) operating activities	169,347	(3,403)	147,809
Investing activities:
Capital expenditures	(30,307)	(34,461)	(118,357)
Capitalized intellectual property costs	(210)	(456)	(3,932)
Proceeds from sale of property, plant and equipment	661	7,353	1,896
Net cash used in investing activities	(29,856)	(27,564)	(120,393)
Financing activities:
Dividends paid	(26)	(6,185)	(18,592)
Proceeds from options exercised	105	0	128
Tax payments related to shares withheld for vested restricted stock and stock units	(5,023)	(703)	(2,993)
(Payments on) proceeds from draw down on the Revolver	(25,000)	25,000	0
Payments on short-term debt	(6,398)	(7,131)	(3,763)
Payments on long-term debt	(12,800)	(15,985)	(23,449)
(Distributions to) contributions from non-controlling interest	(1,103)	1,196	4,554
Principal payments on finance lease obligations	(741)	(45)	(59)
Net cash used in financing activities	(50,986)	(3,853)	(44,174)
Net increase (decrease) in cash and cash equivalents	88,505	(34,820)	(16,758)
Cash and cash equivalents, beginning of period	150,920	185,740	202,498
Cash and cash equivalents, end of period	239,425	150,920	185,740
Cash paid (received) during the period for:
Interest	64,650	73,695	87,286
Taxes, net of refunds	(12,994)	(39,908)	(14,741)
Non-cash Items:
Net assets assumed in business acquisition	68	8,241	0
Accrued capital expenditures	$ 1,196	$ 26,136	$ 27,646

Organization

Organization	12 Months Ended
	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
ORGANIZATION	NOTE A—ORGANIZATION

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	NOTE B—SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation and Consolidation The accompanying Consolidated Financial Statements have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”). In the opinion of management, all adjustments necessary for a fair presentation of the Consolidated Financial Statements have been included. Such adjustments are of a normal, recurring nature. Throughout this report we refer to (i) our Consolidated Balance Sheets as our “Balance Sheets,” (ii) our Consolidated Statements of Operations as our “Income Statements,” and (iii) our Consolidated Statements of Cash Flows as our “Cash Flows.” Consolidation The Consolidated Financial Statements include the accounts of Holdings and its direct and indirect wholly-owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. Reclassifications Certain reclassifications of prior period presentations have been made to conform to the current period presentation. Use of Estimates and Assumptions The preparation of Consolidated Financial Statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the related disclosure of contingent assets and liabilities at the date of the Consolidated Financial Statements and the reported amounts of revenues and expenses during the reporting period. The 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. We base our estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances. Accordingly, actual results may differ significantly from these estimates under different assumptions or conditions. Cash and Cash Equivalents Cash and cash equivalents consist of all highly liquid investments with a maturity of three months or less when purchased. Because of the short maturity of these investments, the carrying amounts approximate their fair value. Cash and cash equivalents are invested primarily in money market securities held by financial institutions with high credit ratings. Accounts at each institution are insured by the Federal Deposit Insurance Corporation. Cash balances at times may exceed federally-insured limits. We have not experienced any losses in such accounts and believe we are not exposed to any significant credit risk on cash. Accounts Receivable The majority of our accounts receivable are due from companies in the oil and natural gas drilling, building and construction products, filler and extenders, filtration, glass, absorbents, sports and recreation, foundry and other major industries. Credit is extended based on evaluation of a customer’s financial condition and, generally, collateral is not required. Accounts receivable are stated at amounts due from customers net of allowance for credit losses. Accounts outstanding longer than the payment terms are considered past due. We determine our allowance by considering a number of factors, including the length of time trade accounts receivable are past due, our previous loss history, the customer’s current ability to pay its obligation to us and the condition of the general economy and the industry as a whole. Ongoing credit evaluations are performed. We write-off accounts receivable when they are deemed uncollectible, and payments subsequently received on such receivables are credited to the allowance for credit losses. See Note F - Accounts Receivable and Note S - Revenue. Inventories Inventories include raw stockpiles, in-process product and finished product available for shipment, as well as spare parts and supplies for routine facility maintenance. We value inventory at the lower of cost and net realizable value. Cost is determined using the first-in, first-out and average cost methods. Our inventoriable costs include production costs and transportation and additional service costs as applicable. See Note G - Inventories. Property, Plant and Mine Development Plant and equipment Plant and equipment is recorded at cost and depreciated over their estimated useful lives. Interest incurred during construction of facilities is capitalized and depreciated over the life of the asset. Costs for normal repairs and maintenance that do not extend economic life or improve service potential are expensed as incurred. Costs of improvements that extend economic life or improve service potential are capitalized and depreciated over the estimated remaining useful life. Depreciation is recorded using the straight-line method over the assets’ estimated useful lives as follows: buildings (15 years); land improvements (10 years); machinery and equipment, including computer equipment and software (3-10 years); furniture and fixtures (8 years). Leasehold improvements are depreciated over the shorter of the asset life or lease term. Construction-in-progress is primarily comprised of machinery and equipment which have not yet been placed in service. Mining property and development Mining property and development includes mineral deposits and mine exploration and development. Mineral deposits are initially recognized at cost, which approximates the estimated fair value on the date of purchase. Mine exploration and development costs include engineering and mineral studies, drilling and other related costs to delineate an ore body, and the removal of overburden to initially expose an ore body for production. Costs incurred before mineralization are classified as proven and probable reserves are expensed and classified as exploration or advanced projects, research and development expense. Capitalization of mine development project costs, which meet the definition of an asset, begins once mineralization is classified as proven and probable reserves. The cost of removing overburden and waste materials to access the ore body at an open pit mine prior to the production phase are referred to as “pre-stripping costs.” Pre-stripping costs are capitalized during the development of an open pit mine. The production phase of an open pit mine commences when saleable minerals, beyond a de minimis amount, are produced. Stripping costs incurred during the production phase of a mine are variable production costs that are included as a component of inventory to be recognized in costs applicable to sales in the same period as the revenue from the sale of inventory. Depletion and amortization of mineral deposits and mine development costs are recorded as the minerals are extracted, based on units of production and engineering estimates of mineable reserves. The impact of revisions to reserve estimates is recognized on a prospective basis. See Note H - Property, Plant and Mine Development. Mine reclamation costs and asset retirement obligations We recognize the fair value of any liability for conditional asset retirement obligations, if sufficient information exists to reasonably estimate the fair value of the liability. These obligations include environmental remediation liabilities when incurred, which is generally upon acquisition, construction or development and/or through the normal operation of the asset. These obligations also generally include the estimated net future costs of dismantling, restoring and reclaiming operating mines and related mine sites in accordance with federal, state, local regulatory and land lease agreement requirements. The liability is accreted over time through periodic charges to earnings. In addition, the asset retirement cost is capitalized as part of the asset’s carrying value and amortized over the life of the related asset. Reclamation costs are periodically adjusted to reflect changes in the estimated present value resulting from the passage of time and revisions to the estimates of either the timing or amount of the reclamation and abandonment costs. The reclamation obligation is based on when spending for an existing environmental disturbance will occur. If the asset retirement obligation is settled for other than the carrying amount of the liability, a gain or loss is recognized on settlement. We review, on an annual basis, unless otherwise deemed necessary, the reclamation obligation at each mine site in accordance with ASC guidance for accounting for reclamation obligations. See Note L - Asset Retirement Obligations. Impairment or Disposal of Property, Plant and Mine Development We periodically evaluate whether current events or circumstances indicate that the carrying value of our property, plant and equipment assets may not be recoverable. If circumstances indicate that the carrying value may not be recoverable, we estimate future undiscounted net cash flows using estimates of proven and probable sand reserves, estimated future sales prices (considering historical and current prices, price trends and related factors) and operating costs and anticipated capital expenditures. If the undiscounted cash flows are less than the carrying value of the assets, we recognize an impairment loss equal to the amount by which the carrying value exceeds the fair value of the assets. The recoverability of the carrying value of our mineral properties is dependent upon the successful development, start-up and commercial production of our mineral deposit and the related processing facilities. Our evaluation of mineral properties for potential impairment primarily includes assessing the existence or availability of required permits and evaluating changes in our mineral reserves, or the underlying estimates and assumptions, including estimated production costs. Assessing the economic feasibility requires certain estimates including the prices of products to be produced and processing recovery rates, as well as operating and capital costs. Gains on the sale of property, plant and mine development are included in income when the assets are disposed of provided there is more than reasonable certainty of the collectability of the sales price and any future activities required to be performed by us relating to the disposal of the assets are complete or insignificant. Upon retirement or disposal of assets, all costs and related accumulated depreciation or amortization are written-off. Goodwill and Other Intangible Assets and Related Impairment Our intangible assets consist of goodwill, which is not amortized, indefinite-lived intangibles, which consist of certain trade names that are not subject to amortization, intellectual property and customer relationships. Intellectual property mainly consists of patents and technology, and it is amortized on a straight-line basis over an average useful life of 15 years. Customer relationships are amortized on a straight-line basis over their useful life of 13 - 20 years. Intangible assets that are amortized are reviewed for impairment annually, or more frequently when indicators of impairment exist. Goodwill represents the excess of the purchase price of business combinations over the fair value of net assets acquired. Goodwill and trade names are reviewed for impairment annually as of October 31, or more frequently when indicators of impairment exist. An impairment exists if the fair value of a reporting unit to which goodwill has been allocated, or the fair value of indefinite-lived intangible assets, is less than their respective carrying values. Prior to conducting a formal impairment test we have an option to assess qualitative factors to determine whether the existence of events or circumstances leads to a determination that is more likely than not (more than 50%) that the fair value of a reporting unit is less than its carrying amount. Such qualitative factors may include the following: macroeconomic conditions; industry and market considerations; cost factors; overall financial performance; and other relevant entity-specific events. If the qualitative assessment determines that an impairment is more likely than not, or if we choose to bypass the qualitative assessment, we perform a quantitative assessment by comparing the fair value of a reporting unit with its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. A trade name is a legally protected trade or similar mark. Acquired trade names are valued using an income method approach, generally the relief-from-royalty valuation method. The method uses a royalty rate based on comparable marketplace royalty agreements for similar types of trade names and applies it to the after-tax discounted free cash flow attributed to the trade name. The discount rate used is based on an estimated weighted average cost of capital and the anticipated risk for intangible assets. The valued trade names have an indefinite life based on our plans and expectations for the trade names going forward and are reviewed for impairment annually, or more frequently when indicators of impairment exist. Intellectual property and technology (“IP”) is a design, work or invention that is the result of creativity to which one has ownership rights that may be protected through a patent, copyright, trademark or service mark. IP is valued using the relief-from-royalty valuation method. The method uses a royalty rate based on comparable marketplace royalty agreements for similar types of IP and applies it to the after-tax discounted free cash flow attributed to the IP. The discount rate used is based on an estimated weighted average cost of capital and the anticipated risk for intangible assets. The IP is amortized following the pattern in which the expected benefits will be consumed or otherwise used up over each component’s useful life, based on our plans and expectations for the IP going forward, which is generally the underlying IP’s legal expiration dates. IP is reviewed for impairment annually, or more frequently when indicators of impairment exist. Customer relationships are intangible assets that consist of historical and factual information about customers and contacts collected from repeat transactions with customers, with or without any underlying contracts. The information is generally organized as customer lists or customer databases. We have the expectation of repeat patronage from these customers based on the customers’ historical purchase activity, which creates the intrinsic value over a finite period of time and translates into the expectation of future revenue, income, and cash flow. Customer relationships are valued using projected operating income, adjusted for estimated future existing customer growth less estimated future customer attrition, net of charges for net tangible assets, IP charge, trade name charge and work force. The concluded value is the after-tax discounted free cash flow. Customer relationships are reviewed for impairment annually, or more frequently when indicators of impairment exist. See Note I - Goodwill and Intangible Assets. Leases We lease railroad cars, office space, mining property, mining/processing equipment, and transportation and other equipment. Operating leases are included in lease right-of-use (“ROU”) assets, current portion of operating lease liabilities, and operating lease liabilities in our consolidated balance sheets. Finance leases are included in lease right-of-use assets, current portion of long-term debt, and long-term debt in our consolidated balance sheets. Leases with an initial term of 12 months or less are not recorded on the balance sheet. ROU assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. ROU assets and liabilities are recognized at the commencement date of the lease based on the present value of lease payments over the lease term. As most of our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. The ROU assets also include any lease payments made at or before the commencement date of the lease and excludes lease incentives. Our lease terms may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Lease expense for lease payments is recognized on a straight-line basis over the lease term. We have lease agreements with lease and non-lease components, the latter of which are generally accounted for separately. See Note Q - Leases. We periodically evaluate whether current events or circumstances indicate that the carrying value of our ROU assets exceeds fair value. If circumstances indicate an impairment exists, we estimate fair value primarily utilizing internally developed cash flow models and quoted market prices, discounted at an appropriate weighted average cost of capital. If the undiscounted cash flows are less than the carrying value of the assets, we recognize an impairment loss equal to the amount by which the carrying value exceeds the fair value of the assets. Revenue Recognition Products We derive our product sales by mining and processing minerals that our customers purchase for various uses. Our product sales are primarily a function of the price per ton and the number of tons sold. We primarily sell our products through individual purchase orders executed under short-term price agreements or at prevailing market rates. The amount invoiced reflects product, transportation and additional handling services as applicable, such as storage, transloading the product from railcars to trucks and last mile logistics to the customer site. We invoice most of our product customers on a per shipment basis, although for some larger customers, we consolidate invoices weekly or monthly. Standard collection terms are net 30 days, although extended terms are offered in competitive situations. We recognize revenue for products and materials at a point in time following the transfer of control of such items to the customer, which typically occurs upon shipment or delivery depending on the terms of the underlying contracts. We account for shipping and handling activities related to product and material sales contracts with customers as costs to fulfill our promise to transfer the associated products pursuant to the accounting policy election allowed under ASC 606-10-25-18b. Accordingly, we record amounts billed for shipping and handling costs as a component of net sales and accrue and classify related costs as a component of cost of sales at the time revenue is recognized. For a limited number of customers, we sell under long-term, minimum purchase supply agreements. These agreements define, among other commitments, the volume of product that our customers must purchase, the volume of product that we must provide and the price that we will charge and that our customers will pay for each product. Prices under these agreements are generally fixed and subject to certain contractual adjustments. Sometimes these agreements may undergo negotiations regarding pricing and volume requirements, which may often occur in volatile market conditions. While these negotiations continue, we may deliver product at prices or at volumes below the requirements in our existing supply agreements. An executed order specifying the type and quantity of product to be delivered, in combination with the noted agreements, comprise our contracts in these arrangements. Service We derive our service revenues primarily through the provision of transportation, equipment rental, and contract labor services to companies in the oil and gas industry. Transportation services typically consist of transporting customer proppant from storage facilities to proximal well-sites and are contracted through work orders executed under established pricing agreements. The amount invoiced reflects the transportation services rendered. Equipment rental services provide customers with use of either dedicated or nonspecific wellhead proppant delivery equipment solutions for contractual periods defined either through formal lease agreements or executed work orders under established pricing agreements. The amounts invoiced reflect the length of time the equipment set was utilized in the billing period. Contract labor services provide customers with proppant delivery equipment operators through work orders executed under established pricing agreements. The amounts invoiced reflect the amount of time our labor services were utilized in the billing period. We typically invoice our customers on a weekly or monthly basis; however, some customers receive invoices upon well-site operation completion. Standard collection terms are net 30 days, although extended terms are offered in competitive situations. We typically recognize revenue for specific, dedicated equipment set rental arrangements under ASC 842, Leases. For the remaining components of service revenue, we have applied the practical expedient allowed under ASC 606-10-55-18 to recognize transportation revenues in proportion to the amount we have the right to invoice. Contracts with Multiple Performance Obligations From time to time, we may enter into contracts that contain multiple performance obligations, such as work orders containing a combination of product, transportation, equipment rentals, and contract labor services. For these arrangements, we allocate the transaction price to each performance obligation identified in the contract based on relative standalone selling prices, or estimates of such prices, and recognize the related revenue as control of each individual product or service is transferred to the customer, in satisfaction of the corresponding performance obligations. We typically invoice our customers on a weekly or monthly basis; however, some customers receive invoices upon well-site operation completion. Standard collection terms are net 30 days, although extended terms are offered in competitive situations. Taxes Collected from Customers and Remitted to Governmental Authorities. We exclude from our measurement of transaction prices all taxes assessed by governmental authorities that are both (i) imposed on and concurrent with a specific revenue-producing transaction and (ii) collected from customers. Accordingly, such tax amounts are not included as a component of net sales or cost of sales. See Note S - Revenue. Deferred Revenues For a limited number of customers, we enter into supply agreements which give customers the right to make advanced payments toward the purchase of certain products at specified volumes over an average initial period of one Unbilled Receivables Revenues recognized in advance of invoice issuance create assets referred to as “unbilled receivables.” Any portion of our unbilled receivables for which our right to consideration is conditional on a factor other than the passage of time is considered a contract asset. These assets are presented on a combined basis with accounts receivable and are converted to accounts receivable once billed. Debt Issuance Costs We defer costs directly associated with acquiring third-party financing, primarily loan origination costs and related professional expenses. Debt issuance costs are deferred and amortized using the effective interest rate method over the term of our senior secured Term Loan facility and the straight-line method for our Revolver facility. Debt issuance costs related to long-term debt are reflected as a direct deduction from the carrying amount of the debt. Amortization included in interest expense was $5.1 million for the year ended December 31, 2021, and $5.1 million and $5.6 million for the years ended December 31, 2020 and 2019. See Note K - Debt. Employee Benefit Plans We provide a range of benefits to our employees and retired employees, including pensions and post-retirement healthcare and life insurance benefits. We record annual amounts relating to these plans based on calculations specified by generally accepted accounting principles, which include various actuarial assumptions, including discount rates, assumed rates of returns, compensation increases, turnover rates, mortality tables, and healthcare cost trend rates. We review the actuarial assumptions on an annual basis and make modifications to the assumptions based on current rates and trends when it is deemed appropriate to do so. As required by U.S. generally accepted accounting principles, the effect of the modifications is generally recorded or amortized over future periods. We believe that the assumptions utilized in recording our obligations under the plans are reasonable based on advice from our actuaries and information as to assumptions used by other employers. See Note P - Pension and Post-Retirement Benefits. Environmental Costs Environmental costs, other than qualifying capital expenditures, are accrued at the time the exposure becomes known and costs can be reasonably estimated. Costs are accrued based upon management’s estimates of all direct costs, after taking into account expected reimbursement by third parties (primarily the sellers of acquired businesses) and are reviewed by outside consultants. Environmental costs are charged to expense unless a settlement with an indemnifying party has been reached. Self-Insurance We are self-insured for various levels of employee health insurance coverage, workers’ compensation and third-party product liability claims alleging occupational disease. We purchase insurance coverage for claim amounts which exceed our self-insured retentions. Depending on the type of insurance, these self-insured retentions range from $0.1 million to $0.5 million per occurrence. Our insurance reserves are accrued based on estimates of the ultimate cost of claims expected to occur during the covered period. These estimates are prepared with the assistance of outside actuaries and consultants. Our actuaries periodically review the volume and amount of claims activity, and based upon their findings, we adjust our insurance reserves accordingly. The ultimate cost of claims for a covered period may differ from our original estimates. The current portion of our self-insurance reserves is included in accrued liabilities and the non-current portion is included in other long-term obligations in our Balance Sheets. As of December 31, 2021 and 2020, our self-insurance reserves totaled $5.8 million and $6.2 million, respectively, of which $2.1 million and $2.4 million, respectively, were classified as current. Research and Development Costs We may incur immaterial internal research and development (“R&D”) expenditures, and research and development conducted for others, all of which are expensed as incurred, and included in selling, general and administrative expense. R&D costs may include, but are not limited to, research and administrative salaries, contractor fees, building costs, utilities, administrative expenses, and allocations of corporate costs. Advertising Costs We recognize advertising expense when incurred as selling, general and administrative expense. Advertising costs have not been a significant component of expense for the years ended December 31, 2021, 2020, or 2019. Equity-based Compensation We grant stock options, restricted stock, restricted stock units and performance share units to certain of our employees and directors under the Amended and Restated U.S. Silica Holdings, Inc. 2011 Incentive Compensation Plan. We recognize the cost of employee services rendered in exchange for awards of equity instruments. Vesting of restricted stock and restricted stock units is based on the individual continuing to render service over a pre-defined vesting schedule, generally three years. Cash dividend equivalents are accrued and paid to the holders of time-based restricted stock units and restricted stock. The fair value of the restricted stock awards is equal to the market price of our stock at date of grant. The restricted award-related compensation expense is recognized on a straight-line basis over the vesting period. We grant performance share units to certain employees in which the number of shares of common stock ultimately received is determined based on achievement of certain performance thresholds over a specified performance period (generally three years) in accordance with the stock award agreement. Cash dividend equivalents are not accrued or paid on performance share units. We recognize expense based on the estimated vesting of our performance share units granted and the grant date market price. The estimated vesting of the performance share units is principally based on the probability of achieving certain financial performance levels during the vesting periods. In the period it becomes probable that the minimum performance criteria specified in the award agreement will be achieved, we recognize expense for the proportionate share of the total fair value of the award related to the vesting period that has already lapsed. The remaining fair value of the award is expensed on a straight-line basis over the remaining vesting period. We grant certain employees performance share units, the vesting of which is based on our total shareholder return (“TSR”) ranking among a peer group over a three-year period. The number of units that will vest will depend on the percentage ranking of our TSR compared to the TSRs for each of the companies in the peer group over the performance period. For these awards subject to market conditions, a binomial-lattice model (i.e., Monte Carlo simulation model) is used to fair value these awards at grant date. The related compensation expense is recognized, on a straight-line basis, over the vesting period. See Note N - Equity-based Compensation. Income Taxes Deferred taxes are recognized on the liability method whereby deferred tax assets are recognized for deductible temporary differences and operating loss and tax credit carry forwards and deferred tax liabilities are recognized for taxable temporary differences. This approach requires recognition of deferred tax liabilities and assets for the expected future tax consequences of events that have been included in the financial statements or tax returns. Under this method, deferred tax liabilities and assets are determined based upon the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the expenses are expected to reverse. Valuation allowances are provided if, based on the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. We recognize a tax benefit associated with an uncertain tax position when, in management’s judgment, it is more likely than not that the position will be sustained upon examination by a taxing authority. For a tax position that meets the more likely than not recognition threshold, we initially and subsequently measure the tax benefit as the largest amount that we judge to have a greater than 50% likelihood of being realized upon ultimate settlement with a taxing authority. The liability associated with unrecognized tax benefits is adjusted periodically due to changing circumstances, such as the progress of tax audits, case law developments and new or emerging legislation. Such adjustments are recognized entirely in the period in which they are identified. The effective tax rate includes the net impact of changes in the liability for unrecognized tax benefits and subsequent adjustments as considered appropriate by management. Generally, the largest permanent item in computing both our effective tax rate and taxable income is

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
EARNINGS PER SHARE	NOTE C—EARNINGS PER SHARE Basic earnings per common share is computed by dividing income available to common stockholders by the weighted average number of common shares outstanding for the period. Diluted earnings per common share is computed similarly to basic earnings per common share except that the weighted average number of common shares outstanding is increased to include the number of additional common shares that would have been outstanding if the potentially dilutive common shares had been issued. The following table shows the computation of basic and diluted earnings per share: In thousands, except per share amounts Year ended December 31, 2021 2020 2019 Numerator: Net loss attributable to U.S. Silica Holdings, Inc. $ (33,761) $ (114,094) $ (329,082) Denominator: Weighted average shares outstanding 74,350 73,634 73,253 Diluted effect of stock awards — — — Weighted average shares outstanding assuming dilution 74,350 73,634 73,253 Loss per share attributable to U.S. Silica Holdings, Inc.: Basic loss per share $ (0.45) $ (1.55) $ (4.49) Diluted loss per share $ (0.45) $ (1.55) $ (4.49) Potentially dilutive shares were excluded from the calculation of diluted weighted average shares outstanding and diluted earnings per share because we were in a loss position. Certain stock options, restricted stock awards and performance share units were excluded from the computation of diluted earnings per share because their effect would have been anti-dilutive. Such potentially dilutive shares and stock awards (in thousands) excluded from the calculation of diluted earnings (loss) per common share were as follows: Year ended December 31, 2021 2020 2019 Potentially dilutive shares excluded 1,714 238 68 Stock options excluded 667 826 711 Restricted stock and performance share units awards excluded 66 3,435 1,298

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	12 Months Ended
	Dec. 31, 2021
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	NOTE D—ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) Accumulated Other Comprehensive Income (Loss) Accumulated other comprehensive income (loss) consists of fair value adjustments associated with accumulated adjustments for net experience gains or losses and prior service cost related to employee benefit plans and foreign currency translation adjustments, net of tax. The following table presents the changes in accumulated other comprehensive income (loss) by component (in thousands): For the Year Ended December 31, 2021 Foreign currency translation adjustments Pension and other post-retirement benefits liability Total Beginning Balance $ 583 $ (9,062) $ (8,479) Other comprehensive (loss) income before reclassifications (1,000) 9,035 8,035 Amounts reclassed from accumulated other comprehensive income — 793 793 Ending Balance $ (417) $ 766 $ 349 Any amounts reclassified from accumulated other comprehensive income (loss) 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	12 Months Ended
	Dec. 31, 2021
Business Combination and Asset Acquisition [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 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 Consolidated Financial Statements represented our best estimates and valuations. In accordance with the acquisition method of accounting, the fair values were subject to adjustment until we completed our analysis, which was during the first quarter of 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 $20.1 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 $17.6 million was recorded in "Other income, net, including interest income" in the Consolidated Statement of Operations. During the first quarter of 2021, we recorded a $0.1 million increase to accounts receivable, which was our final adjustment to the purchase price. The total adjustments during the measurement period 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 Consolidated Statement of Operations.

Accounts Receivable

Accounts Receivable	12 Months Ended
	Dec. 31, 2021
Receivables [Abstract]
ACCOUNTS RECEIVABLE	NOTE F—ACCOUNTS RECEIVABLE Accounts receivable (in thousands) consisted of the following: December 31, 2021 December 31, 2020 Trade receivables $ 182,992 $ 171,230 Less: Allowance for credit losses (5,248) (6,604) Net trade receivables 177,744 164,626 Other receivables (1) 25,015 42,308 Total accounts receivable $ 202,759 $ 206,934 (1) At December 31, 2021 and 2020, other receivables included $21.5 million and $37.4 million of refunds related to NOL carryback claims filed for various tax years in accordance with certain provisions of the CARES Act. 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) disaggregated by portfolio segments: Oil & Gas Proppants Industrial & Specialty Products Total Beginning balance, December 31, 2020 $ 5,684 $ 920 $ 6,604 Allowance for credit losses (1,000) 545 (455) Write-offs (59) (842) (901) Ending balance, December 31, 2021 $ 4,625 $ 623 $ 5,248

Inventories

Inventories	12 Months Ended
	Dec. 31, 2021
Inventory Disclosure [Abstract]
INVENTORIES	NOTE G—INVENTORIES Inventories (in thousands) consisted of the following: December 31, 2021 December 31, 2020 Supplies $ 45,605 $ 42,329 Raw materials and work in process 36,529 33,723 Finished goods 33,579 28,632 Total inventories $ 115,713 $ 104,684

Property, Plant and Mine Develo

Property, Plant and Mine Development	12 Months Ended
	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
PROPERTY, PLANT AND MINE DEVELOPMENT	NOTE H—PROPERTY, PLANT AND MINE DEVELOPMENT Property, plant and mine development (in thousands) consisted of the following: December 31, 2021 December 31, 2020 Mining property and mine development $ 789,122 $ 788,287 Asset retirement cost 22,283 15,985 Land 55,541 54,710 Land improvements 76,248 76,002 Buildings 72,207 69,841 Machinery and equipment 1,189,548 1,171,382 Furniture and fixtures 3,932 4,071 Construction-in-progress 35,060 27,216 2,243,941 2,207,494 Accumulated depletion, depreciation, amortization and impairment charges (985,295) (839,402) Total property, plant and mine development, net $ 1,258,646 $ 1,368,092 Depreciation, depletion, and amortization expense related to property, plant and mine development for the years ended December 31, 2021 and 2020 was $149.6 million and $143.8 million, respectively. During the years ended 2020 and 2019, impairment charges were recorded mainly related to facilities that have reduced capacity or have been idled, including Tyler, Texas, Sparta, Wisconsin, Utica, Illinois, and Kosse, Texas. These charges relate to the Oil & Gas Proppants segment and are recorded in "Goodwill and other asset impairments" in the Consolidated Statements of Operations. See Note W - Impairments for additional information. During the year ended 2020, management approved the disposal of certain non-operating parcels of land. The assets, which had a combined carrying value of approximately $3.2 million were classified as assets held for sale and were presented within Prepaid expenses and other current assets in the Consolidated Balance Sheets. The proceeds of the disposals were expected to equal or exceed the net carrying value of the assets and, accordingly, no impairment loss was recognized on these assets held for sale. The assets were previously classified as Land, therefore, no adjustments were needed for depreciation. We disposed of these assets within one year of the balance sheet date. During the fourth quarter of 2020, we sold these assets at a gain of $0.3 million which was recorded in Other income, net, including interest income in the Consolidated Statements of Operations.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND INTANGIBLE ASSETS	NOTE I—GOODWILL AND INTANGIBLE ASSETS The changes in the carrying amount of goodwill (in thousands) by business segment consisted of the following: Oil & Gas Proppants Segment Industrial & Specialty Products Segment Total Balance at December 31, 2019 $ 86,100 $ 187,424 $ 273,524 Impairment losses (86,100) — (86,100) EPMH acquisition adjustment (1) — (1,775) (1,775) Balance at December 31, 2020 — 185,649 185,649 Impairment losses — — — Balance at December 31, 2021 $ — $ 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 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. As a result of triggering events identified during the year ended 2020, we performed a quantitative analysis. The fair value of our reporting units was determined using a combination of the discounted cash flow method and the market multiples approach. As a result of this analysis we determined that goodwill was impaired. We recognized goodwill impairment charges of $86.1 million. This impairment charge related to our Oil & Gas Proppants segment and was recorded in the "Goodwill and other asset impairments" caption of our Consolidated Statements of Operations. No impairment charges were recorded related to goodwill during the years ended 2019 or 2021. See Note W - Impairments for additional information. The changes in the carrying amount of intangible assets (in thousands) consisted of the following: December 31, 2021 December 31, 2020 Gross Carrying Amount Accumulated Amortization Impairments Net Gross Carrying Amount Accumulated Amortization Impairments Net Technology and intellectual property $ 71,209 $ (25,069) $ (38) $ 46,102 $ 71,052 $ (18,854) $ (1,373) $ 50,825 Customer relationships 66,999 (27,987) — 39,012 66,999 (23,182) — 43,817 Total definite-lived intangible assets: $ 138,208 $ (53,056) $ (38) $ 85,114 $ 138,051 $ (42,036) $ (1,373) $ 94,642 Trade names 64,240 — — 64,240 65,390 — (1,150) 64,240 Other 700 — — 700 700 — — 700 Total intangible assets: $ 203,148 $ (53,056) $ (38) $ 150,054 $ 204,141 $ (42,036) $ (2,523) $ 159,582 During the year ended 2020, we recorded impairments related to trade names and technology and intellectual property. See Note W - Impairments for additional information. Estimated useful life of technology and intellectual property is 15 years. Estimated useful life of customer relationships is a range of 13 - 20 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 Consolidated Statement of Operations. Amortization expense was $9.7 million, $10.3 million and $10.8 million for the years ended December 31, 2021, 2020, and 2019, respectively. At December 31, 2021, the estimated amortization expense related to definite-lived intangible assets (in thousands) for the five succeeding years is as follows: 2022 $ 9,674 2023 $ 9,669 2024 $ 9,670 2025 $ 9,669 2026 $ 9,669

Accounts Payable and Accrued Li

Accounts Payable and Accrued Liabilities	12 Months Ended
	Dec. 31, 2021
Payables and Accruals [Abstract]
ACCOUNTS PAYABLE AND ACCRUED LIABILITIES	NOTE J—ACCOUNTS PAYABLE AND ACCRUED LIABILITIES Accounts payable and accrued liabilities (in thousands) consisted of the following: December 31, 2021 2020 Trade payables $ 134,494 $ 90,564 Accrued salaries and wages 11,347 7,432 Accrued vacation liability 2,847 2,499 Current portion of liability for pension and post-retirement benefits 1,227 1,338 Accrued healthcare liability 1,619 1,886 Accrued property taxes and sales taxes 4,625 5,136 Vendor incentives — 4,782 Other accrued liabilities 11,511 8,283 Accounts payable and accrued liabilities $ 167,670 $ 121,920 Other accrued liabilities consist of employer related expenses, royalties payable, accrued interest payable, and other items.

Debt

Debt	12 Months Ended
	Dec. 31, 2021
Debt Disclosure [Abstract]
DEBT	NOTE K—DEBT Debt (in thousands) consisted of the following: December 31, 2021 December 31, 2020 Senior secured credit facility: Revolver expiring May 1, 2023 (4.13% at December 31, 2021 and 4.19% at December 31, 2020) $ — $ 25,000 Term Loan facility—final maturity May 1, 2025 (5.00% at December 31, 2021 and 5.00% December 31, 2020) 1,222,000 1,234,800 Less: Unamortized original issue discount (3,350) (4,376) Less: Unamortized debt issuance cost (15,200) (20,259) Insurance financing notes payable 4,424 4,187 Finance leases 3,546 350 Total debt 1,211,420 1,239,702 Less: current portion (18,285) (42,042) Total long-term portion of debt $ 1,193,135 $ 1,197,660 Senior Secured Credit Facility On May 1, 2018, we entered into a Third Amended and Restated Credit Agreement (the "Credit Agreement"), which increased our existing senior debt by entering into a new $1.380 billion senior secured Credit Facility, consisting of a $1.280 billion term loan (the "Term Loan") and a $100 million revolving credit facility (the "Revolver") (collectively the "Credit Facility") that may also be used for swingline loans or letters of credit, and we may elect to increase the term loan in accordance with the terms of the Credit Agreement. Borrowings under the Credit Agreement will bear interest at variable rates as determined at our election, at LIBOR or a base rate, in each case, plus an applicable margin. In addition, under the Credit Agreement, we are required to pay a per annum facility fee and fees for letters of credit. The Credit Agreement is secured by substantially all of our assets and of our domestic subsidiaries' assets and a pledge of the equity interests in such entities. The Term Loan matures on May 1, 2025, and the Revolver expires on May 1, 2023. We capitalized $38.7 million in debt issuance costs and original issue discount as a result of the new Credit Agreement. The Credit Agreement contains covenants that, among other things, limit our ability, and certain of our subsidiaries' abilities, to create, incur or assume indebtedness and liens, to make acquisitions or investments, to sell assets and to pay dividends. The Credit Agreement also requires us to maintain a consolidated leverage ratio of no more than 3.75:1.00 as of the last day of any fiscal quarter whenever usage of the Revolver (other than certain undrawn letters of credit) exceeds 30% of the Revolver commitment. These covenants are subject to a number of important exceptions and qualifications. The Credit Agreement includes events of default and other affirmative and negative covenants that are usual for facilities and transactions of this type. As of December 31, 2021 and 2020, we were in compliance with all covenants in accordance with our senior secured Credit Facility. Term Loan At December 31, 2021, contractual maturities of our senior secured Credit Facility (in thousands) are as follows: 2022 $ 12,800 2023 12,800 2024 12,800 2025 1,183,600 2026 — Thereafter — Total $ 1,222,000 Revolving Line-of-Credit We have a $100.0 million Revolver with zero drawn and $22.2 million allocated for letters of credit as of December 31, 2021, leaving $77.8 million available under the Revolver. Based on our consolidated leverage ratio of 5.41:1.00 as of December 31, 2021, we may draw up to $30.0 million without the consent of our lenders. With the consent of our lenders, we have access to the full availability of the Revolver. Note Payable Secured by Royalty Interest In conjunction with the acquisition of New Birmingham, Inc. in August 2016, we assumed a note payable secured by a royalty interest. During the fourth quarter of 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 plans to resume production. Therefore, no amounts have been accrued. The settlement of the note payable resulted in a gain of $8.3 million which was recorded in Other income, net, including interest income in the Consolidated Statements of Operations. Insurance Financing Notes Payable During the third quarter of 2021, we renewed our insurance policies and financed the payments through notes payable with a stated interest rate of 2.9%. These payments will be made in installments throughout a nine-month period and, as such, were classified as current debt. As of December 31, 2021, the notes payable had a balance of $4.4 million.

Asset Retirement Obligations

Asset Retirement Obligations	12 Months Ended
	Dec. 31, 2021
Asset Retirement Obligation Disclosure [Abstract]
ASSET RETIREMENT OBLIGATIONS	NOTE L—ASSET RETIREMENT OBLIGATIONS Mine reclamation or future remediation costs for inactive mines are accrued based on management’s best estimate at the end of each period of the costs expected to be incurred at a site. Such cost estimates include, where applicable, ongoing care, maintenance and monitoring costs. Changes in estimates at inactive mines are reflected in earnings in the period an estimate is revised. Liabilities related to our asset retirement obligations are recorded in other long-term liabilities on our balance sheets. Changes in the asset retirement obligations (in thousands) are as follows: December 31, 2021 December 31, 2020 Beginning balance $ 24,717 $ 25,825 Accretion 1,450 1,434 Additions and revisions of estimates 5,882 (2,542) Ending balance $ 32,049 $ 24,717

Fair Value Accounting

Fair Value Accounting	12 Months Ended
	Dec. 31, 2021
Fair Value Disclosures [Abstract]
FAIR VALUE ACCOUNTING	NOTE M—FAIR VALUE ACCOUNTING Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Fair value is estimated by applying the following hierarchy, which prioritizes the inputs used to measure fair value into three levels and bases the categorization within the hierarchy upon the lowest level of input that is available and significant to the fair value measurement: Level 1—Quoted prices in active markets for identical assets or liabilities. Level 2—Observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3—Inputs that are generally unobservable and typically reflect management’s estimate of assumptions that market participants would use in pricing the asset or liability. Cash Equivalents Due to the short-term maturity, we believe our cash equivalent instruments at December 31, 2021 and 2020, 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.

Equity-Based Compensation

Equity-Based Compensation	12 Months Ended
	Dec. 31, 2021
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, amended and restated effective February 1, 2020, and amended and restated effective May 13, 2021. The 2011 Plan provides for grants of stock options, restricted stock, performance share units and other incentive-based awards. We believe our 2011 Plan aligns the interests of our employees and directors with those of our common stockholders. At December 31, 2021, we had 3,852,762 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: Number of Weighted Aggregate Intrinsic Value Weighted Outstanding at December 31, 2020 826,215 $ 29.05 $ — 3.1 years Granted — $ — $ — Exercised (10,164) $ 10.33 $ 44 Forfeited (113,333) $ 24.76 $ — Expired (36,000) $ 14.58 $ — Outstanding at December 31, 2021 666,718 $ 30.84 $ — 2.4 years Exercisable at December 31, 2021 666,718 $ 30.84 $ — 2.4 years There were no grants of stock options during the years ended December 31, 2021, 2020 and 2019. There were 10,164, zero and 10,000 stock options exercised during the years ended December 31, 2021, 2020 and 2019, respectively. The total intrinsic value of stock options exercised was $44 thousand, zero and $12 thousand for the years ended December 31, 2021, 2020 and 2019, respectively. Cash received from stock options exercised during the years ended December 31, 2021, 2020 and 2019 was $105 thousand, zero and $128 thousand, respectively. The tax benefits realized from stock option exercises were $11 thousand, zero and $3 thousand for the years ended December 31, 2021, 2020 and 2019, respectively. As of December 31, 2021, 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: Number of Shares Grant Date Weighted Unvested, December 31, 2020 1,779,826 $ 6.22 Granted 881,261 $ 9.82 Vested (1,491,222) $ 6.44 Forfeited (25,555) $ 11.63 Unvested, December 31, 2021 1,144,310 $ 8.37 We granted 881,261, 1,590,170 and 814,387 restricted stock and restricted stock unit awards during the years ended December 31, 2021, 2020 and 2019, respectively. The fair value of the awards was based on the market price of our stock at date of grant. We recognized $7.3 million, $8.1 million and $8.2 million of equity-based compensation expense related to restricted stock awards during the years ended December 31, 2021, 2020 and 2019, respectively. As of December 31, 2021, there was $7.5 million of unrecognized compensation expense related to these restricted stock awards, which is expected to be recognized over a weighted-average period of 1.7 years. We also granted cash awards during the year ended December 31, 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 $0.9 million and $0.6 million of expense related to these awards for the years ended December 31, 2021 and 2020. The liability for these awards is included in accounts payable and other accrued expenses on our balance sheets. These awards will be remeasured at fair value each reporting period with resulting changes reflected in our income statements. Estimated unrecognized expense related to these awards is $0.8 million over a period of 1.1 years. Performance Share Unit Awards The following table summarizes the status of, and changes in, our performance share unit awards: Number of Shares Grant Date Weighted Unvested, December 31, 2020 1,513,648 $ 12.36 Granted 886,091 $ 12.04 Vested (292,241) $ 17.48 Forfeited/Cancelled (192,909) $ 29.10 Unvested, December 31, 2021 1,914,589 $ 9.77 We granted 886,091, 1,020,161 and 607,130 of performance share unit awards during the years ended December 31, 2021, 2020 and 2019, respectively. A portion of these awards was measured against total shareholder return ("TSR"), and a portion was measured against adjusted free cash flow ("ACF") targets. The grant date weighted average fair value of these awards was estimated to be $12.04, $6.57 and $15.58 for the years ended December 31, 2021, 2020 and 2019, respectively. The number of TSR measured units that will vest will depend on the percentage ranking of our TSR compared to the TSR for each of the companies in the peer group over the three year period from January 1, 2021 through December 31, 2023 for the 2021 grant, from January 1, 2020 through December 31, 2022 for the 2020 grant, and January 1, 2019 through December 31, 2021 for the 2019 grant. The number of ACF measured units that will vest will be based on ACF achievement versus target. The ACF targets are set annually and are approved by the Board of Directors. The related compensation expense is recognized on a straight-line basis over the vesting period. The grant date fair value for the TSR 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 $11.5 million, $6.8 million and $7.7 million of compensation expense related to performance share unit awards during the years ended December 31, 2021, 2020 and 2019, respectively. As of December 31, 2021, there was $10.0 million of unrecognized compensation expense related to these performance share unit awards, which is expected to be recognized over a weighted-average period of 1.6 years. We also granted cash awards during the year ended December 31, 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 and $0.9 million of expense related to these awards for the years ended December 31, 2021 and 2020. The liability for these awards is included in accounts payable and other accrued expenses on our balance sheets. These awards will be remeasured at fair value each reporting period with resulting changes reflected in our income statements. Estimated unrecognized expense related to these awards is $0.6 million over a period of 1.1 years.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	NOTE O—COMMITMENTS AND CONTINGENCIES Future Minimum Annual Commitments (in thousands): Year ending December 31, Minimum Purchase Commitments 2022 $ 15,065 2023 10,386 2024 5,397 2025 2,886 2026 2,180 Thereafter 9,288 Total future purchase commitments $ 45,202 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 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 years ended December 31, 2021, 2020 and 2019, two, one and one claims, respectively, were brought against U.S. Silica. As of December 31, 2021, there were 44 active silica-related products liability claims pending in which U.S. Silica is a defendant. Although the outcomes of these claims cannot be predicted with certainty, in the opinion of management, it is not reasonably possible that the ultimate resolution of these matters will have a material adverse effect on our financial position or results of operations that exceeds the accrual amounts. We have recorded estimated liabilities for these claims in other long-term obligations as well as estimated recoveries under the indemnity agreement and an estimate of future recoveries under insurance in other assets on our consolidated balance sheets. As of both December 31, 2021 and 2020, other non-current assets included zero for insurance for third-party products liability claims, and other long-term obligations included $0.9 million and $1.0 million, respectively, for third-party products liability claims. Obligations Under Guarantees

Pension and Post-Retirement Ben

Pension and Post-Retirement Benefits	12 Months Ended
	Dec. 31, 2021
Retirement Benefits [Abstract]
PENSION AND POST-RETIREMENT BENEFITS	NOTE P— PENSION AND POST-RETIREMENT BENEFITS We maintain a single-employer noncontributory defined benefit pension plan covering certain employees. The plan is frozen to all new employees. The plan provides benefits based on each covered employee’s years of qualifying service. Our funding policy is to contribute amounts within the range of the minimum required and maximum deductible contributions for the plan consistent with a goal of appropriate minimization of the unfunded projected benefit obligations. The pension plan uses a benefit level per year of service for covered hourly employees and a final average pay method for covered salaried employees. The plan uses the projected unit credit cost method to determine the actuarial valuation. We employ a total rate of return investment approach whereby a mix of equities and fixed income investments are used to maximize the long-term return of plan assets for a prudent level of risk. Risk tolerance is established through careful consideration of plan liabilities, plan funded status, and corporate financial condition. The investment portfolio contains a diversified blend of equity and fixed-income investments. Furthermore, equity investments are diversified across U.S. and non-U.S. stocks, as well as growth, value and small and large capitalizations. Investment risk is measured and monitored on an ongoing basis through quarterly investment portfolio reviews, annual liability measurements, and periodic asset/liability studies. We employ a building block approach in determining the long-term rate of return for plan assets. Historical markets are studied and long-term historical relationships between equities and fixed-income are preserved consistent with the widely accepted capital market principle that assets with higher volatility generate a greater return over the long run. Current market factors such as inflation and interest rates are evaluated before long-term capital market assumptions are determined. The long-term portfolio return is established via a building block approach with proper consideration of diversification and rebalancing. Peer data and historical returns are reviewed to check for reasonability and appropriateness. In addition, we provide defined benefit post-retirement 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: Year Ended 2021 2020 2019 Service cost $ 2,855 $ 2,253 $ 1,304 Interest cost 2,619 4,037 5,375 Expected return on plan assets (5,688) (6,019) (6,171) Net amortization and deferral 3,212 3,127 1,648 Net pension benefit costs $ 2,998 $ 3,398 $ 2,156 Net post-retirement benefit cost (in thousands) consisted of the following: Year Ended December 31, 2021 2020 2019 Service cost $ 24 $ 70 $ 88 Interest cost 141 584 789 Unrecognized net (gain)/loss (2,204) — (29) Net post-retirement benefit costs $ (2,039) $ 654 $ 848 The changes in benefit obligations and plan assets (in thousands), as well as the funded status (in thousands) of our pension and post-retirement plans were as follows: Pension Benefits Post-retirement Benefits 2021 2020 2021 2020 Benefit obligation at January 1, $ 157,198 $ 148,491 $ 11,318 $ 22,054 Service cost 2,855 2,253 24 70 Interest cost 2,619 4,037 141 584 Actuarial (gain) loss (6,637) 11,119 (3,193) 1,329 Benefits paid (9,551) (8,649) (680) (1,751) Other (2,233) (53) 1,781 (10,968) Benefit obligation at December 31, $ 144,251 $ 157,198 $ 9,391 $ 11,318 Fair value of plan assets at January 1, $ 120,563 $ 110,431 $ — $ — Actual return on plan assets 7,099 13,306 — — Employer contributions 2,800 5,475 579 1,335 Benefits paid (9,551) (8,649) (680) (1,751) Other — — 101 416 Fair value of plan assets at December 31, $ 120,911 $ 120,563 $ — $ — Plan assets less than benefit obligations at December 31 recognized as liability for pension and other post-retirement benefits $ (23,340) $ (36,635) $ (9,391) $ (11,318) The accumulated benefit obligation for the defined benefit pension plans, which excludes the assumption of future salary increases, totaled $144.3 million and $157.2 million at December 31, 2021 and 2020, respectively. We also sponsor unfunded, nonqualified pension plans. The projected benefit obligation, accumulated benefit obligation and fair value of plan assets for these plans were $1.5 million, $1.5 million and zero, respectively, at December 31, 2021 and $1.6 million, $1.6 million and zero, respectively, at December 31, 2020. Future estimated annual benefit payments (in thousands) for pension and post-retirement benefit obligations were as follows: Benefits Post-retirement Pension Before After 2022 $ 9,526 $ 1,104 $ 1,104 2023 9,446 983 983 2024 9,539 911 911 2025 9,367 795 795 2026 9,271 742 742 2027-2031 43,405 2,775 2,775 Our best estimate of expected contributions to the pension and post-retirement medical benefit plans for the 2022 fiscal year are zero and $1.1 million, respectively. The total amounts in accumulated other comprehensive income (loss) related to net actuarial loss for the pension and post-retirement plans were $10.2 million and $24.7 million as of December 31, 2021 and 2020, respectively. The total amounts in accumulated other comprehensive income (loss) related to prior service cost for the pension and post-retirement plans, were gains of $7.8 million and $9.4 million as of December 31, 2021 and 2020, respectively. The actuarial losses in 2021 and 2020 were primarily driven by the change in discount rates on the U.S. qualified plan and postretirement medical plans. The impact of the discount rate change was partially offset by the actual return on plan assets exceeding the expected return on plan assets. Additionally, the Society of Actuaries released an updated mortality table projection scale for measurement of retirement program obligations in both 2021 and 2020. The impact of the mortality table changes provided a partial offset of the impact of the discount rate change. The following weighted-average assumptions were used to determine our obligations under the plans: Pension Benefits Post-retirement Benefits 2021 2020 2021 2020 Discount rate 2.8 % 2.5 % 2.6 % 2.1 % Long-term rate of compensation increase N/A 3.0% N/A N/A Long-term rate of return on plan assets 5.8 % 6.3% N/A N/A Health care cost trend rate: Pre-65 initial rate/ultimate rate N/A N/A 6.2%/4.5% 6.5%/4.5% Pre-65 ultimate year N/A N/A 2028 2028 Post-65 initial rate/ultimate rate N/A N/A N/A/N/A 7.0%/4.5% Post-65 ultimate year N/A N/A N/A 2028 The weighted average discount rates used to determine the projected pension and post-retirement obligations were updated to reflect the expected long-term rates of return with maturities comparable to payments for the plan obligations utilizing Aon Hewitt's AA Above Medium Curve. Mortality tables used for pension benefits and post-retirement benefits plans were the following: Pension and Post-retirement Benefits 2021 2020 Healthy Lives Pri-2012 base mortality tables with generational mortality improvements using Scale MP-2021 Pri-2012 base mortality tables with generational mortality improvements using Scale MP-2020 Disabled Lives Pri-2012 base mortality tables with generational mortality improvements using Scale MP-2021 Pri-2012 base mortality tables with generational mortality improvements using Scale MP-2020 The major investment categories and their relative percentage of the fair value of total plan assets as invested were as follows: Pension Benefits Post-retirement Benefits (1) 2021 2020 2021 2020 Equity securities 51.6 % 57.9 % — % — % Debt securities 46.1 % 41.3 % — % — % Cash 2.3 % 0.8 % — % — % (1) Retiree health benefits are paid by the Company as covered expenses are incurred. The fair values of the pension plan assets (in thousands) at December 31, 2021, by asset category, were as follows: Level 1 Level 2 Level 3 Total Cash and cash equivalents $ — $ 2,743 $ — $ 2,743 Mutual funds: Diversified emerging markets 6,375 — — 6,375 Foreign large blend 21,719 — — 21,719 Large-cap blend 22,907 — — 22,907 Mid-cap blend 11,411 — — 11,411 Real estate — — — — Fixed income securities: Corporate notes and bonds 35,365 — — 35,365 U.S. Treasuries 6,915 — — 6,915 Mortgage-backed securities — 2,242 — 2,242 Asset-backed securities — 1,739 — 1,739 Real Assets — 9,495 — 9,495 Net asset $ 104,692 $ 16,219 $ — $ 120,911 The fair values of the pension plan assets (in thousands) at December 31, 2020, by asset category, were as follows: Level 1 Level 2 Level 3 Total Cash and cash equivalents $ — $ 1,020 $ — $ 1,020 Mutual funds: Diversified emerging markets 7,064 — — 7,064 Foreign large blend 22,638 — — 22,638 Large-cap blend 22,272 — — 22,272 Mid-cap blend 12,972 — — 12,972 Real estate 4,822 — — 4,822 Fixed income securities: Corporate notes and bonds 38,983 — — 38,983 U.S. Treasuries 8,582 — — 8,582 Mortgage-backed securities — 1,780 — 1,780 Asset-backed securities — 430 — 430 Net asset $ 117,333 $ 3,230 $ — $ 120,563 We contribute to three multiemployer defined benefit pension plans under the terms of collective-bargaining agreements for union-represented employees. A multiemployer plan is subject to collective bargaining for employees of two or more unrelated companies. These plans allow multiple employers to pool their pension resources and realize efficiencies associated with the daily administration of the plan. Multiemployer plans are generally governed by a board of trustees composed of management and labor representatives and are funded through employer contributions. However, in most cases, management is not directly represented. The risks of participating in multiemployer plans differ from single employer plans as follows: 1) assets contributed to a multiemployer plan by one employer may be used to provide benefits to employees of other participating employers, 2) if a participating employer stops contributing to the plan, the unfunded obligations of the plan may be borne by the remaining participating employers, and 3) if we cease to have an obligation to contribute to one or more of the multiemployer plans to which we contribute, we may be required to pay those plans an amount based on the underfunded status of the plan, referred to as a withdrawal liability. A summary of each multiemployer pension plan for which we participate is presented below: Pension EIN/ Pension Pension Protection Act Zone Status (1) FIP/RP Status Company Surcharge Expiration 2021 2020 2021 2020 2019 LIUNA 52-6074345/001 Green Green No $ 378 $ 361 $ 385 No 6/4/2022 IUOE 36-6052390/001 Green Green No 328 256 310 No 7/31/2022 CSSS (2) 36-6044243/001 Red Red Yes 51 51 51 NA NA (1) The Pension Protection Act of 2006 defines the zone status as follows: green—healthy, yellow—endangered, orange—seriously endangered and red—critical. (2) In 2011, we withdrew from the Central States, Southeast and Southwest Areas Pension Plan. The withdrawal liability of $1.0 million will be paid in monthly installments of $4,000 until 2031. Our contributions to individual multiemployer pension funds did not exceed 5% of the fund’s total contributions for the years ended December 31, 2021, 2020 and 2019. Additionally, our contributions to multiemployer post-retirement benefit plans were immaterial for all periods presented in the accompanying consolidated financial statements. We also sponsor a defined contribution plan covering certain employees. We contribute to the plan in two ways. For certain employees not covered by the defined benefit plan, we make a contribution equal to 4% of their salary. For all other eligible employees, we make a contribution of up to 6% of eligible earnings. Contributions were $5.9 million, $4.4 million and $7.1 million for the years ended December 31, 2021, 2020 and 2019, respectively.

Leases

Leases	12 Months Ended
	Dec. 31, 2021
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 approximately one year to 20 years. Our lease terms may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. We have lease agreements with lease and non-lease components, the latter of which are generally accounted for separately. Supplemental balance sheet information related to leases (in thousands except for term and rate information) was as follows: Leases Classification December 31, 2021 December 31, 2020 Assets Operating Lease right-of-use assets $ 38,793 $ 37,130 Finance Lease right-of-use assets 3,448 339 Total leased assets $ 42,241 $ 37,469 Liabilities Current Operating Current portion of operating lease liabilities $ 14,469 $ 17,388 Finance Current portion of long-term debt 1,061 55 Non-Current Operating Operating lease liabilities 75,130 76,361 Finance Long-term debt, net 2,485 295 Total lease liabilities $ 93,145 $ 94,099 During 2020, we recorded impairment charges related to railcar leases, various equipment leases and an office building lease. These charges relate to the Oil & Gas Proppants segment and are recorded in "Goodwill and other asset impairments" in the Consolidated Statements of Operations. See Note W - Impairments for additional information. During the year ended 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 year ended December 31, 2020, we recorded a decrease to the ROU assets of $1.0 million and a decrease to the liability of $25.0 million. A gain of $24.0 million was recognized as operating income through cost of goods sold in our consolidated income statement for the year ended December 31, 2020. Operating lease liabilities are based on the net present value of the remaining lease payments over the remaining lease term. As most of our leases do not provide an implicit rate, in determining the lease liability and the present value of lease payments, we used our incremental borrowing rate based on the information available at the lease commencement date. The weighted average remaining lease term and discount rate related to leases were as follows: Lease Term and Discount Rate December 31, 2021 December 31, 2020 Weighted average remaining lease term: Operating leases 6.9 years 6.9 years Finance leases 3.6 years 2.9 years Weighted average discount rate: Operating leases 5.7 % 5.8 % Finance leases 5.1 % 5.0 % The components of lease expense included in our Consolidated Statements of Operations were as follows: Lease Costs Classification Year Ended Year Ended Operating lease costs (1) Cost of Sales $ 33,185 $ 26,548 Operating lease costs (2) Selling, general, and administrative 1,880 1,808 Right-of-use asset impairment Goodwill and other asset impairments — 3,406 Total (3) $ 35,065 $ 31,762 (1) Includes short-term operating lease costs of $17.9 million and $9.6 million for the years ended December 31, 2021 and 2020, respectively. (2) Includes short-term operating lease costs of $0.4 million and $0.4 million for the years ended December 31, 2021 and 2020, respectively. (3) Does not include expense of $0.8 million and $12 thousand for the years ended December 31, 2021 and 2020 for finance leases. Supplemental cash flow information related to leases was as follows: Year Ended December 31, 2021 Year Ended December 31, 2020 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows for operating leases $ 24,451 $ 62,140 Operating cash flows for finance leases $ 759 $ 12 Right-of-use assets obtained in exchange for new lease liabilities: Operating leases $ 17,350 $ 10,747 Finance leases $ 3,815 $ 359 Maturities of lease liabilities as of December 31, 2021: Maturities of lease liabilities Operating leases Finance leases 2022 $ 20,128 $ 1,209 2023 19,889 1,199 2024 16,441 764 2025 13,019 605 2026 11,116 71 Thereafter 30,642 — Total lease payments $ 111,235 $ 3,848 Less: Interest 17,939 302 Less: Other operating expenses 3,697 — Total $ 89,599 $ 3,546
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 approximately one year to 20 years. Our lease terms may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. We have lease agreements with lease and non-lease components, the latter of which are generally accounted for separately. Supplemental balance sheet information related to leases (in thousands except for term and rate information) was as follows: Leases Classification December 31, 2021 December 31, 2020 Assets Operating Lease right-of-use assets $ 38,793 $ 37,130 Finance Lease right-of-use assets 3,448 339 Total leased assets $ 42,241 $ 37,469 Liabilities Current Operating Current portion of operating lease liabilities $ 14,469 $ 17,388 Finance Current portion of long-term debt 1,061 55 Non-Current Operating Operating lease liabilities 75,130 76,361 Finance Long-term debt, net 2,485 295 Total lease liabilities $ 93,145 $ 94,099 During 2020, we recorded impairment charges related to railcar leases, various equipment leases and an office building lease. These charges relate to the Oil & Gas Proppants segment and are recorded in "Goodwill and other asset impairments" in the Consolidated Statements of Operations. See Note W - Impairments for additional information. During the year ended 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 year ended December 31, 2020, we recorded a decrease to the ROU assets of $1.0 million and a decrease to the liability of $25.0 million. A gain of $24.0 million was recognized as operating income through cost of goods sold in our consolidated income statement for the year ended December 31, 2020. Operating lease liabilities are based on the net present value of the remaining lease payments over the remaining lease term. As most of our leases do not provide an implicit rate, in determining the lease liability and the present value of lease payments, we used our incremental borrowing rate based on the information available at the lease commencement date. The weighted average remaining lease term and discount rate related to leases were as follows: Lease Term and Discount Rate December 31, 2021 December 31, 2020 Weighted average remaining lease term: Operating leases 6.9 years 6.9 years Finance leases 3.6 years 2.9 years Weighted average discount rate: Operating leases 5.7 % 5.8 % Finance leases 5.1 % 5.0 % The components of lease expense included in our Consolidated Statements of Operations were as follows: Lease Costs Classification Year Ended Year Ended Operating lease costs (1) Cost of Sales $ 33,185 $ 26,548 Operating lease costs (2) Selling, general, and administrative 1,880 1,808 Right-of-use asset impairment Goodwill and other asset impairments — 3,406 Total (3) $ 35,065 $ 31,762 (1) Includes short-term operating lease costs of $17.9 million and $9.6 million for the years ended December 31, 2021 and 2020, respectively. (2) Includes short-term operating lease costs of $0.4 million and $0.4 million for the years ended December 31, 2021 and 2020, respectively. (3) Does not include expense of $0.8 million and $12 thousand for the years ended December 31, 2021 and 2020 for finance leases. Supplemental cash flow information related to leases was as follows: Year Ended December 31, 2021 Year Ended December 31, 2020 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows for operating leases $ 24,451 $ 62,140 Operating cash flows for finance leases $ 759 $ 12 Right-of-use assets obtained in exchange for new lease liabilities: Operating leases $ 17,350 $ 10,747 Finance leases $ 3,815 $ 359 Maturities of lease liabilities as of December 31, 2021: Maturities of lease liabilities Operating leases Finance leases 2022 $ 20,128 $ 1,209 2023 19,889 1,199 2024 16,441 764 2025 13,019 605 2026 11,116 71 Thereafter 30,642 — Total lease payments $ 111,235 $ 3,848 Less: Interest 17,939 302 Less: Other operating expenses 3,697 — Total $ 89,599 $ 3,546

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
INCOME TAXES	NOTE R— INCOME TAXES We evaluate our deferred tax assets periodically to determine if valuation allowances are required. Ultimately, the realization of deferred tax assets is dependent upon generation of future taxable income during those periods in which temporary differences become deductible and/or credits can be utilized. To this end, management considers the level of historical taxable income, the scheduled reversal of deferred tax liabilities, tax-planning strategies and projected future taxable income. Based on these considerations, and the carry-forward availability of a portion of the deferred tax assets, management believes it is more likely than not that we will realize the benefit of the deferred tax assets. 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, permitted NOL carryovers and carrybacks to offset 100% of taxable income for taxable years beginning after 2017 and before 2021. In addition, the CARES Act allowed 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, during 2020, we 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 during the second quarter of 2020. We 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, of which $4.9 million was received during the fourth quarter of 2020. At December 31, 2021, the remaining $21.5 million of this refund was included in accounts receivable in our balance sheets. 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, for the year ended December 31, 2020, we recorded a deferred tax benefit of $22.3 million. Income (loss) before income taxes (in thousands) consisted of the following: Year ended December 31, 2021 2020 2019 United States $ (48,328) $ (183,656) $ (435,918) Foreign 11,252 8,509 7,010 Total $ (37,076) $ (175,147) $ (428,908) Income tax benefit (in thousands) consisted of the following: Year ended December 31, 2021 2020 2019 Current: Federal $ — $ — $ — State (3,353) (307) (1,188) Foreign (1,385) (1,473) (1,343) (4,738) (1,780) (2,531) Deferred: Federal 7,589 57,214 90,457 State (96) 4,591 11,225 Foreign — — — 7,493 61,805 101,682 Income tax benefit $ 2,755 $ 60,025 $ 99,151 Income tax benefit (in thousands) differed from the amount that would be provided by applying the U.S. federal statutory rate due to the following: Year ended December 31, 2021 2020 2019 Income tax benefit computed at U.S. federal statutory rate $ 7,786 $ 36,781 $ 90,070 Decrease (increase) resulting from: Statutory depletion 2,012 1,230 4,679 Prior year tax return reconciliation (2,490) (2,084) 3,121 State income taxes, net of federal benefit 445 5,013 9,486 Unrecognized tax benefits (1,302) — — Adjustment to deferred taxes from the CARES Act — 22,318 — Equity compensation (627) (1,477) (6,440) Executive compensation (2,092) (579) (722) Other, net (977) (1,177) (1,043) Income tax benefit $ 2,755 $ 60,025 $ 99,151 Generally, the largest permanent item in computing both our effective tax rate and taxable income is the deduction allowed for statutory depletion. The deduction for statutory depletion does not necessarily change proportionately to changes in income before income taxes. However, for the year ended 2020, we recorded a permanent tax benefit related to the CARES Act, which represents the largest permanent item in computing our effective tax rate for 2020. Deferred tax assets and liabilities are recognized for the estimated future tax effects, based on enacted tax laws, of temporary differences between the values of assets and liabilities recorded for financial reporting and for tax purposes and of net operating loss and other carryforwards. The tax effects of the types of temporary differences and carry forwards that gave rise to deferred tax assets and liabilities (in thousands) consisted of the following: December 31, 2021 2020 Gross deferred tax assets: Net operating loss carry forward and state tax credits $ 77,327 $ 90,087 Pension and post-retirement benefit costs 7,318 11,146 Property, plant and equipment 8,619 6,866 Accrued expenses 14,930 12,397 Inventories 1,200 121 Federal tax credits 4,188 4,188 Stock-based compensation expense 4,359 4,307 Interest expense limitation 16,921 14,127 Intangibles 7,876 11,304 Lease obligation liability 13,297 14,154 Other 4,399 5,286 Total deferred tax assets 160,434 173,983 Gross deferred tax liabilities: Land and mineral property basis difference (121,211) (122,265) Fixed assets and depreciation (83,708) (100,640) Other (289) (464) Total deferred tax liabilities (205,208) (223,369) Net deferred tax liabilities $ (44,774) $ (49,386) We have federal net operating loss carry forwards of approximately $317.1 million at December 31, 2021. A portion of those losses are subject to an annual limitation under Internal Revenue Code Section 382, but are expected to be fully realized. NOL deductions generated in tax years after December 31, 2017 can offset 100% of taxable income for periods prior to 2021 but only 80% of taxable income after 2020. The CARES Act also prohibits NOL carrybacks on NOLs generated after December 31, 2020 but allows indefinite carryforwards. As of December 31, 2021, we have general business credits of approximately $4.2 million, which will expire beginning in 2033. These credits are expected to be fully realized. The CARES Act also accelerated the ability of companies to receive refunds of alternative minimum tax ("AMT") credits related to tax years beginning in 2018 and 2019. AMT credits were presented as a receivable or a deferred tax asset in the prior period balance sheets. The presentation of refundable AMT credits in the balance sheet was reclassified during 2020 from deferred tax asset to accounts receivable to reflect the timing of when the credits were expected to be monetized. AMT credits in the amount of $16.0 million were included in accounts receivable on our balance sheets as of December 31, 2020, and were received in full during the first quarter of 2021. The following table is a reconciliation of our unrecognized tax benefits: Year ended December 31, 2021 2020 2019 Balance as of January 1 $ — $ — $ — Additions for tax positions of prior years 856 — — Balance as of December 31 $ 856 $ — $ — If the unrecognized tax benefits of $0.9 million are realized, this would negatively impact the effective tax rate. As of December 31, 2021, 2020 and 2019, we had approximately $0.4 million, zero, and zero, respectively, of interest and penalties related to uncertain tax positions. During 2021, 2020 and 2019, we accrued and recognized estimated interest and penalties related to uncertain tax positions of approximately $0.4 million, zero and zero, respectively. We include potential interest and penalties related to uncertain tax positions in the income tax (expense)/benefit line item in our consolidated statements of operations. We do not expect a significant change to the unrecognized tax benefits during the next twelve months. Tax returns filed with the IRS for the years 2018 through 2020 along with tax returns filed with numerous state entities remain subject to examination.

Revenue

Revenue	12 Months Ended
	Dec. 31, 2021
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 reflects our sales disaggregated by major source (in thousands): Year Ended December 31, 2021 Year Ended December 31, 2020 Category Oil & Gas Proppants Industrial & Specialty Products Total Sales Oil & Gas Proppants Industrial & Specialty Products Total Sales Product $ 407,772 $ 488,431 $ 896,203 $ 301,199 $ 430,988 $ 732,187 Service 207,676 — 207,676 113,698 — 113,698 Total Sales $ 615,448 $ 488,431 $ 1,103,879 $ 414,897 $ 430,988 $ 845,885 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 (in thousands): Unbilled Receivables December 31, 2021 December 31, 2020 Beginning Balance $ 47,982 $ 20,144 Reclassifications to billed receivables (105,305) (10,330) Revenues recognized in excess of period billings 59,280 38,168 Ending Balance $ 1,957 $ 47,982 We enter into certain customer supply agreements which give the customers the right to purchase certain products for a discounted price at certain volumes over an average initial contract term of one Deferred Revenue December 31, 2021 December 31, 2020 Beginning Balance $ 33,692 $ 50,634 Revenues recognized from balances held at the beginning of the period (13,172) (19,704) Revenues deferred from period collections on unfulfilled performance obligations 5,207 6,627 Revenues recognized from period collections (4,986) (3,865) Ending Balance $ 20,741 $ 33,692 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 fees assessed to multiple customers according to contract terms as of December 31, 2021 and 2020. For the years ended December 31, 2021 and 2020, we recognized revenue as variable consideration from shortfall fees according to contract terms in the amounts of $58.6 million and $48.0 million, respectively. In some cases, amounts recorded are estimates which are in negotiation and may increase or decrease. We believe these amounts are the best estimates of revenue to recognize as of year end. During the second quarter of 2021, we entered into an agreement to settle a customer dispute regarding fees related to minimum purchase commitments from 2014-2020. As a result of this settlement, we recognized approximately $49.0 million in revenue as of June 30, 2021. These amounts were received in full during the second and third quarters of 2021. Foreign Operations The following table includes information related to our foreign operations (in thousands): For the years ended December 31, 2021 December 31, 2020 December 31, 2019 Total Sales $ 96,317 $ 86,179 $ 92,788 Pre-tax income $ 11,252 $ 8,509 $ 7,010 Net income $ 8,889 $ 6,722 $ 5,538 Foreign operations constituted approximately $30.7 million and $31.0 million of consolidated assets as of December 31, 2021 and 2020, respectively.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2021
Related Party Transactions [Abstract]
RELATED PARTY TRANSACTIONS	NOTE T— RELATED PARTY TRANSACTIONS There were no related party transactions during the years ended December 31, 2021, 2020 or 2019.

Segment Reporting

Segment Reporting	12 Months Ended
	Dec. 31, 2021
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 600 product types and materials used in a variety of markets including building and construction products, fillers and extenders, filtration, glassmaking, absorbents, foundry, and sports and recreation. An operating segment’s performance is primarily evaluated based on segment contribution margin, which excludes selling, general, and administrative costs, corporate costs, plant capacity expansion expenses, and facility closure costs. We believe that segment contribution margin, as defined above, is an appropriate measure for evaluating the operating performance of our segments. However, segment contribution margin is a non-GAAP measure and should be considered in addition to, not a substitute for, or superior to, net income (loss) or other measures of financial performance prepared in accordance with GAAP. The other accounting policies of each of the two reportable segments are the same as those in Note B - Summary of Significant Accounting Policies to these Consolidated Financial Statements. The following table presents sales and segment contribution margin (in thousands) for the reportable segments and other operating results not allocated to the reported segments for the years ended December 31, 2021, 2020 and 2019: Year Ended 2021 2020 2019 Sales: Oil & Gas Proppants $ 615,448 $ 414,897 $ 1,010,521 Industrial & Specialty Products 488,431 430,988 463,956 Total sales 1,103,879 845,885 1,474,477 Segment contribution margin: Oil & Gas Proppants 160,052 142,041 248,594 Industrial & Specialty Products 168,499 159,176 178,215 Total segment contribution margin 328,551 301,217 426,809 Operating activities excluded from segment cost of sales (19,655) (30,402) (85,625) Selling, general and administrative (119,628) (124,171) (150,848) Depreciation, depletion and amortization (161,131) (155,568) (179,444) Goodwill and other asset impairments (202) (110,688) (363,847) Interest expense (71,157) (79,885) (95,472) Other income, net, including interest income 6,146 24,350 19,519 Income tax benefit 2,755 60,025 99,151 Net loss $ (34,321) $ (115,122) $ (329,757) Less: Net loss attributable to non-controlling interest (560) (1,028) (675) Net loss attributable to U.S. Silica Holdings, Inc. $ (33,761) $ (114,094) $ (329,082)

Parent Company Financials

Parent Company Financials	12 Months Ended
	Dec. 31, 2021
Condensed Financial Information Disclosure [Abstract]
PARENT COMPANY FINANCIALS	NOTE V— PARENT COMPANY FINANCIALS U.S. SILICA HOLDINGS, INC. (PARENT COMPANY ONLY) CONDENSED BALANCE SHEETS December 31, 2021 2020 (in thousands) ASSETS Current Assets: Cash and cash equivalents $ 46,996 $ 46,851 Due from affiliates 165,632 168,276 Total current assets 212,628 215,127 Investment in subsidiaries 401,691 412,169 Total assets $ 614,319 $ 627,296 LIABILITIES AND STOCKHOLDERS’ EQUITY Current Liabilities: Accrued expenses and other current liabilities $ 50 $ 286 Dividends payable 186 219 Total current liabilities 236 505 Total liabilities 236 505 Stockholders’ Equity: Preferred stock — — Common stock 845 827 Additional paid-in capital 1,218,575 1,200,023 Retained deficit (429,260) (395,496) Treasury stock, at cost (186,294) (181,615) Accumulated other comprehensive income (loss) 349 (8,479) Total U.S. Silica Holdings, Inc. stockholders’ equity 604,215 615,260 Non-controlling interest 9,868 11,531 Total stockholders' equity 614,083 626,791 Total liabilities and stockholders’ equity $ 614,319 $ 627,296 U.S. SILICA HOLDINGS, INC. (PARENT COMPANY ONLY) CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) Year ended December 31, 2021 2020 2019 (in thousands) Sales $ — $ — $ — Cost of sales — — — Operating expenses Selling, general and administrative 252 253 253 Total operating expenses 252 253 253 Operating loss (252) (253) (253) Other income (expense) Interest income 5 210 1,440 Total other income 5 210 1,440 (Loss) income before income taxes and equity in net earnings of subsidiaries (247) (43) 1,187 Income tax expense — — (327) (Loss) income before equity in net earnings of subsidiaries (247) (43) 860 Equity in earnings of subsidiaries, net of tax (34,074) (115,079) (330,617) Net loss (34,321) (115,122) (329,757) Less: Net loss attributable to non-controlling interest (560) (1,028) (675) Net loss attributable to U.S. Silica Holdings, Inc. (33,761) (114,094) (329,082) Net loss (34,321) (115,122) (329,757) Other comprehensive (loss) income Unrealized gain (loss) on derivatives (net of tax of $—, $973, and $(456) for 2021, 2020, and 2019, respectively) — 3,053 (1,432) Foreign currency translation adjustment (net of tax of $(309), $444, and $(60) for 2021, 2020 and 2019, respectively) (1,000) 1,391 (188) Pension and other post-retirement benefits liability adjustment (net of tax of $3,131, $2,207, and $(1,024) for 2021, 2020 and 2019, respectively) 9,828 6,931 (3,214) Comprehensive loss (25,493) (103,747) (334,591) Less: Comprehensive loss attributable to non-controlling interest (560) (1,028) (675) Comprehensive loss attributable to U.S. Silica Holdings, Inc. (24,933) (102,719) (333,916) U.S. SILICA HOLDINGS, INC. (PARENT COMPANY ONLY) CONDENSED STATEMENTS OF STOCKHOLDERS' EQUITY (amounts in thousands) Par Value Treasury Stock Additional Paid-In Capital Retained Earnings (Deficit) - Present Accumulated Other Comprehensive (Loss) Income Total U.S. Silica, Inc. Stockholders' Equity Non-controlling Interest Total Balance at January 1, 2019 $ 818 $ (178,215) $ 1,169,383 $ 67,854 $ (15,020) $ 1,044,820 $ 7,484 $ 1,052,304 Net loss — — — (329,082) — (329,082) (675) (329,757) Unrealized loss on derivatives — — — — (1,432) (1,432) — (1,432) Foreign currency translation adjustment — — — — (188) (188) — (188) Pension and post-retirement liability — — — — (3,214) (3,214) — (3,214) Cash dividend declared ($0.25 per share) — — — (18,728) — (18,728) — (18,728) Contributions from non-controlling interest — — — — — — 4,554 4,554 Common stock-based compensation plans activity: Equity-based compensation — — 15,906 — — 15,906 — 15,906 Proceeds from options exercised — 296 (168) — — 128 — 128 Shares withheld for employee taxes related to vested restricted stock and stock units 5 (2,993) (5) — — (2,993) — (2,993) Balance at December 31, 2019 $ 823 $ (180,912) $ 1,185,116 $ (279,956) $ (19,854) $ 705,217 $ 11,363 $ 716,580 Net loss — — — (114,094) — (114,094) (1,028) (115,122) Unrealized gain on derivatives — — — — 3,053 3,053 — 3,053 Foreign currency translation adjustment — — — — 1,391 1,391 — 1,391 Pension and post-retirement liability — — — — 6,931 6,931 — 6,931 Cash dividend declared ($0.02 per share) — — — (1,446) — (1,446) — (1,446) Contributions from non-controlling interest — — — — — — 1,196 1,196 Common stock-based compensation plans activity: Equity-based compensation — — 14,911 — — 14,911 — 14,911 Shares withheld for employee taxes related to vested restricted stock and stock units 4 (703) (4) — — (703) — (703) Balance at December 31, 2020 $ 827 $ (181,615) $ 1,200,023 $ (395,496) $ (8,479) $ 615,260 $ 11,531 $ 626,791 Net loss — — — (33,761) — (33,761) (560) (34,321) Foreign currency translation adjustment — — — — (1,000) (1,000) — (1,000) Pension and post-retirement liability — — — — 9,828 9,828 — 9,828 Cash dividends — — — (3) — (3) — (3) Distributions to non-controlling interest — — — — — — (1,103) (1,103) Common stock-based compensation plans activity: Equity-based compensation — — 18,809 — — 18,809 — 18,809 Proceeds from options exercised — 344 (239) — — 105 — 105 Shares withheld for employee taxes related to vested restricted stock and stock units 18 (5,023) (18) — — (5,023) — (5,023) Balance at December 31, 2021 $ 845 $ (186,294) $ 1,218,575 $ (429,260) $ 349 $ 604,215 $ 9,868 $ 614,083 U.S. SILICA HOLDINGS, INC. (PARENT COMPANY ONLY) CONDENSED STATEMENTS OF CASH FLOWS Year ended December 31, 2021 2020 2019 (in thousands) Operating activities: Net loss $ (34,321) $ (115,122) $ (329,757) Adjustments to reconcile net (loss) income to net cash provided by operating activities: Undistributed loss from equity method investment, net 34,074 115,079 330,617 Changes in assets and liabilities, net of effects of acquisitions: Accounts payable and accrued liabilities (236) 155 (88) Net cash (used in) provided by operating activities (483) 112 772 Investing activities: Investment in subsidiary — — — Net cash used in investing activities — — — Financing activities: Dividends paid (26) (6,185) (18,592) Proceeds from options exercised 105 — 128 Tax payments related to shares withheld for vested restricted stock and stock units (5,023) (703) (2,993) (Distributions to) contributions from non-controlling interest (1,103) 1,196 4,554 Net financing activities with subsidiaries 6,675 582 (39,171) Net cash provided by (used in) financing activities 628 (5,110) (56,074) Net increase (decrease) in cash and cash equivalents 145 (4,998) (55,302) Cash and cash equivalents, beginning of period 46,851 51,849 107,151 Cash and cash equivalents, end of period $ 46,996 $ 46,851 $ 51,849 Supplemental cash flow information: Cash received during the period for: Interest $ (17) $ (210) $ (1,440) Notes to Condensed Financial Statements of Registrant (Parent Company Only) These condensed parent company only financial statements have been prepared in accordance with Rule 12-04, Schedule I of Regulation S-X, because the restricted net assets of the subsidiaries of U.S. Silica Holdings, Inc. (as defined in Rule 4-08(e)(3) of Regulation S-X) exceed 25% of our consolidated net assets. The ability of our operating subsidiaries to pay dividends may be restricted due to the terms of our Credit Facility, as discussed in Note K - Debt to these financial statements. These condensed parent company financial statements have been prepared using the same accounting principles and policies described in the notes to the consolidated financial statements; the only exceptions are that (a) the parent company accounts for its subsidiaries using the equity method of accounting, (b) taxes are allocated to the parent from the subsidiary using the separate return method, and (c) intercompany loans are not eliminated. In the parent company financial statements, our investment in subsidiaries is stated at cost plus equity in undistributed earnings of subsidiaries since the date of acquisition. These condensed parent company financial statements should be read in conjunction with our consolidated financial statements and related notes thereto included elsewhere in this report. No cash dividends were paid to the parent by its consolidated entities for the years presented in the condensed financial statements.

Impairments

Impairments	12 Months Ended
	Dec. 31, 2021
Disclosure Text Block Supplement [Abstract]
IMPAIRMENTS	NOTE W— IMPAIRMENTS We recorded impairment charges (in thousands) for the following assets: Description December 31, 2021 December 31, 2020 December 31, 2019 Inventories, net $ — $ 6,837 $ 4,100 Property, plant and mine development, net 164 11,822 243,064 Operating lease right-of-use assets — 3,406 115,443 Goodwill — 86,100 — Intangible assets, net 38 2,523 1,240 Total $ 202 $ 110,688 $ 363,847 2020 Impairments 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 a sharp reduction 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 completed impairment assessments for our assets, including plant, property and mine development, right-of-use assets, inventories, and other intangible assets. Inventories, net We recorded impairment charges primarily related to unused inventory at plants we idled. These charges relate to the Oil & Gas Proppants segment and are recorded in "Goodwill and other asset impairments" in the Consolidated Statements of Operations. Property, plant and mine development We estimated the future undiscounted net cash flows of certain asset groupings using estimates of proven and probable sand reserves, estimated future sales prices (considering historical and current prices, price trends and related factors) and operating costs and anticipated capital expenditures. In the cases where the undiscounted cash flows are less than the carrying value of the assets, we recognized an impairment loss equal to the amount by which the carrying value exceeds the fair value of the assets. Impairment charges were recorded related primarily to our Kosse, Texas facility, which was idled. These charges relate to the Oil & Gas Proppants segment and are recorded in "Goodwill and other asset impairments" in the Consolidated Statements of Operations. Operating lease right-of-use assets We determined the fair value of the railcars primarily utilizing internally developed cash flow models and quoted market prices, discounted at an appropriate weighted average cost of capital. As a result, we recognized impairment charges primarily related to various equipment leases and an office building lease. These charges relate mainly to the Oil & Gas Proppants segment and are recorded in "Goodwill and other asset impairments" in the Consolidated Statements of Operations. Goodwill We performed a quantitative analysis and determined that the goodwill of our Oil & Gas Proppants reporting unit was impaired. We recognized goodwill impairment charges during the first quarter of 2020. These impairment charges were recorded in the "Goodwill and other asset impairments" caption of our Consolidated Statements of Operations. The fair value of our reporting units was determined using the discounted cash flow method. Intangible assets, net We recorded impairments of $1.1 million for trade names and $1.4 million for patents and intellectual property as of December 31, 2020, which was recorded in the Industrial & Specialty Products segment as a result of the discontinuance of a minor product line. These charges were recorded in the "Goodwill and other asset impairments" caption of our Consolidated Statements of Operations. 2019 Impairments During the fourth quarter of 2019, similar to the fourth quarter of 2018, we experienced a sharp decline in customer demand for Northern White frac sand and for regional non-in-basin frac sand as more tons are produced and sold in-basin. Additionally, the price of frac sand decreased significantly. Given the changes in demand and customer preferences of local in-basin sand, we also experienced a significant decline in the utilization of the sand railcar fleet in our transload network. A significant number of sand railcars were put into storage and were no longer used to deliver sand to our customers. In response to these economic conditions, we implemented numerous cost reductions including headcount reductions and a reduction of frac sand capacity at multiple locations. As a result of the aforementioned triggering events, which occurred in the fourth quarter of 2019, we completed an impairment assessment of our frac sand-related assets, including plant, property and mine development, right-of-use assets, inventories, and other intangible assets. Inventories, net We recorded impairment charges for unused inventory at frac sand plants we idled. These charges relate to the Oil & Gas Proppants segment and are recorded in "Goodwill and other asset impairments" in the Consolidated Statements of Operations. Property, plant and mine development We estimated the future undiscounted net cash flows of asset groupings, which are at the plant level, using estimates of proven and probable sand reserves, estimated future sales prices (considering historical and current prices, price trends and related factors) and operating costs and anticipated capital expenditures. In the cases where the undiscounted cash flows are less than the carrying value of the assets, we recognized an impairment loss equal to the amount by which the carrying value exceeds the fair value of the assets. Impairment charges were recorded mainly related to facilities that have reduced capacity or have been idled, including Tyler, Texas, Sparta, Wisconsin, and Utica, Illinois. These charges relate to the Oil & Gas Proppants segment and are recorded in "Goodwill and other asset impairments" in the Consolidated Statements of Operations. Operating lease right-of-use assets We determined the fair value of the railcars primarily utilizing internally developed cash flow models and quoted market prices, discounted at an appropriate weighted average cost of capital. As a result, we recognized impairment charges to write down the value of railcars to their estimated fair value. These charges relate mainly to the Oil & Gas Proppants segment and are recorded in "Goodwill and other asset impairments" in the Consolidated Statements of Operations. Intangible assets, net

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2021
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	NOTE X-SUBSEQUENT EVENTS

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation and Consolidation	Basis of Presentation and Consolidation The accompanying Consolidated Financial Statements have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”). In the opinion of management, all adjustments necessary for a fair presentation of the Consolidated Financial Statements have been included. Such adjustments are of a normal, recurring nature. Throughout this report we refer to (i) our Consolidated Balance Sheets as our “Balance Sheets,” (ii) our Consolidated Statements of Operations as our “Income Statements,” and (iii) our Consolidated Statements of Cash Flows as our “Cash Flows.”
Consolidation	Consolidation The Consolidated Financial Statements include the accounts of Holdings and its direct and indirect wholly-owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation.
Reclassifications	Reclassifications Certain reclassifications of prior period presentations have been made to conform to the current period presentation.
Use of Estimates and Assumptions	Use of Estimates and Assumptions The preparation of Consolidated Financial Statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the related disclosure of contingent assets and liabilities at the date of the Consolidated Financial Statements and the reported amounts of revenues and expenses during the reporting period. The 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. We base our estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances. Accordingly, actual results may differ significantly from these estimates under different assumptions or conditions.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents consist of all highly liquid investments with a maturity of three months or less when purchased. Because of the short maturity of these investments, the carrying amounts approximate their fair value. Cash and cash equivalents are invested primarily in money market securities held by financial institutions with high credit ratings. Accounts at each institution are insured by the Federal Deposit Insurance Corporation. Cash balances at times may exceed federally-insured
Accounts Receivables	Accounts ReceivableThe majority of our accounts receivable are due from companies in the oil and natural gas drilling, building and construction products, filler and extenders, filtration, glass, absorbents, sports and recreation, foundry and other major industries. Credit is extended based on evaluation of a customer’s financial condition and, generally, collateral is not required. Accounts receivable are stated at amounts due from customers net of allowance for credit losses. Accounts outstanding longer than the payment terms are considered past due. We determine our allowance by considering a number of factors, including the length of time trade accounts receivable are past due, our previous loss history, the customer’s current ability to pay its obligation to us and the condition of the general economy and the industry as a whole. Ongoing credit evaluations are performed. We write-off accounts receivable when they are deemed uncollectible, and payments subsequently received on such receivables are credited to the allowance for credit losses.
Inventories	InventoriesInventories include raw stockpiles, in-process product and finished product available for shipment, as well as spare parts and supplies for routine facility maintenance. We value inventory at the lower of cost and net realizable value. Cost is determined using the first-in, first-out and average cost methods. Our inventoriable costs include production costs and transportation and additional service costs as applicable.
Property, Plant and Mine Development	Property, Plant and Mine Development Plant and equipment Plant and equipment is recorded at cost and depreciated over their estimated useful lives. Interest incurred during construction of facilities is capitalized and depreciated over the life of the asset. Costs for normal repairs and maintenance that do not extend economic life or improve service potential are expensed as incurred. Costs of improvements that extend economic life or improve service potential are capitalized and depreciated over the estimated remaining useful life. Depreciation is recorded using the straight-line method over the assets’ estimated useful lives as follows: buildings (15 years); land improvements (10 years); machinery and equipment, including computer equipment and software (3-10 years); furniture and fixtures (8 years). Leasehold improvements are depreciated over the shorter of the asset life or lease term. Construction-in-progress is primarily comprised of machinery and equipment which have not yet been placed in service. Mining property and development Mining property and development includes mineral deposits and mine exploration and development. Mineral deposits are initially recognized at cost, which approximates the estimated fair value on the date of purchase. Mine exploration and development costs include engineering and mineral studies, drilling and other related costs to delineate an ore body, and the removal of overburden to initially expose an ore body for production. Costs incurred before mineralization are classified as proven and probable reserves are expensed and classified as exploration or advanced projects, research and development expense. Capitalization of mine development project costs, which meet the definition of an asset, begins once mineralization is classified as proven and probable reserves. The cost of removing overburden and waste materials to access the ore body at an open pit mine prior to the production phase are referred to as “pre-stripping costs.” Pre-stripping costs are capitalized during the development of an open pit mine. The production phase of an open pit mine commences when saleable minerals, beyond a de minimis amount, are produced. Stripping costs incurred during the production phase of a mine are variable production costs that are included as a component of inventory to be recognized in costs applicable to sales in the same period as the revenue from the sale of inventory. Depletion and amortization of mineral deposits and mine development costs are recorded as the minerals are extracted, based on units of production and engineering estimates of mineable reserves. The impact of revisions to reserve estimates is recognized on a prospective basis. See Note H - Property, Plant and Mine Development. Mine reclamation costs and asset retirement obligations We recognize the fair value of any liability for conditional asset retirement obligations, if sufficient information exists to reasonably estimate the fair value of the liability. These obligations include environmental remediation liabilities when
Impairment or Disposal of Property, Plant and Mine Development	Impairment or Disposal of Property, Plant and Mine Development We periodically evaluate whether current events or circumstances indicate that the carrying value of our property, plant and equipment assets may not be recoverable. If circumstances indicate that the carrying value may not be recoverable, we estimate future undiscounted net cash flows using estimates of proven and probable sand reserves, estimated future sales prices (considering historical and current prices, price trends and related factors) and operating costs and anticipated capital expenditures. If the undiscounted cash flows are less than the carrying value of the assets, we recognize an impairment loss equal to the amount by which the carrying value exceeds the fair value of the assets. The recoverability of the carrying value of our mineral properties is dependent upon the successful development, start-up and commercial production of our mineral deposit and the related processing facilities. Our evaluation of mineral properties for potential impairment primarily includes assessing the existence or availability of required permits and evaluating changes in our mineral reserves, or the underlying estimates and assumptions, including estimated production costs. Assessing the economic feasibility requires certain estimates including the prices of products to be produced and processing recovery rates, as well as operating and capital costs. Gains on the sale of property, plant and mine development are included in income when the assets are disposed of provided there is more than reasonable certainty of the collectability of the sales price and any future activities required to be performed by us relating to the disposal of the assets are complete or insignificant. Upon retirement or disposal of assets, all costs and related accumulated depreciation or amortization are written-off.
Goodwill and Other Intangible Assets and Related Impairment	Goodwill and Other Intangible Assets and Related Impairment Our intangible assets consist of goodwill, which is not amortized, indefinite-lived intangibles, which consist of certain trade names that are not subject to amortization, intellectual property and customer relationships. Intellectual property mainly consists of patents and technology, and it is amortized on a straight-line basis over an average useful life of 15 years. Customer relationships are amortized on a straight-line basis over their useful life of 13 - 20 years. Intangible assets that are amortized are reviewed for impairment annually, or more frequently when indicators of impairment exist. Goodwill represents the excess of the purchase price of business combinations over the fair value of net assets acquired. Goodwill and trade names are reviewed for impairment annually as of October 31, or more frequently when indicators of impairment exist. An impairment exists if the fair value of a reporting unit to which goodwill has been allocated, or the fair value of indefinite-lived intangible assets, is less than their respective carrying values. Prior to conducting a formal impairment test we have an option to assess qualitative factors to determine whether the existence of events or circumstances leads to a determination that is more likely than not (more than 50%) that the fair value of a reporting unit is less than its carrying amount. Such qualitative factors may include the following: macroeconomic conditions; industry and market considerations; cost factors; overall financial performance; and other relevant entity-specific events. If the qualitative assessment determines that an impairment is more likely than not, or if we choose to bypass the qualitative assessment, we perform a quantitative assessment by comparing the fair value of a reporting unit with its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. A trade name is a legally protected trade or similar mark. Acquired trade names are valued using an income method approach, generally the relief-from-royalty valuation method. The method uses a royalty rate based on comparable marketplace royalty agreements for similar types of trade names and applies it to the after-tax discounted free cash flow attributed to the trade name. The discount rate used is based on an estimated weighted average cost of capital and the anticipated risk for intangible assets. The valued trade names have an indefinite life based on our plans and expectations for the trade names going forward and are reviewed for impairment annually, or more frequently when indicators of impairment exist. Intellectual property and technology (“IP”) is a design, work or invention that is the result of creativity to which one has ownership rights that may be protected through a patent, copyright, trademark or service mark. IP is valued using the relief-from-royalty valuation method. The method uses a royalty rate based on comparable marketplace royalty agreements for similar types of IP and applies it to the after-tax discounted free cash flow attributed to the IP. The discount rate used is based on an estimated weighted average cost of capital and the anticipated risk for intangible assets. The IP is amortized following the pattern in which the expected benefits will be consumed or otherwise used up over each component’s useful life, based on our plans and expectations for the IP going forward, which is generally the underlying IP’s legal expiration dates. IP is reviewed for impairment annually, or more frequently when indicators of impairment exist.
Leases	Leases We lease railroad cars, office space, mining property, mining/processing equipment, and transportation and other equipment. Operating leases are included in lease right-of-use (“ROU”) assets, current portion of operating lease liabilities, and operating lease liabilities in our consolidated balance sheets. Finance leases are included in lease right-of-use assets, current portion of long-term debt, and long-term debt in our consolidated balance sheets. Leases with an initial term of 12 months or less are not recorded on the balance sheet. ROU assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. ROU assets and liabilities are recognized at the commencement date of the lease based on the present value of lease payments over the lease term. As most of our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. The ROU assets also include any lease payments made at or before the commencement date of the lease and excludes lease incentives. Our lease terms may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Lease expense for lease payments is recognized on a straight-line basis over the lease term. We have lease agreements with lease and non-lease components, the latter of which are generally accounted for separately. See Note Q - Leases.
Revenue Recognition and Deferred Revenues	Revenue Recognition Products We derive our product sales by mining and processing minerals that our customers purchase for various uses. Our product sales are primarily a function of the price per ton and the number of tons sold. We primarily sell our products through individual purchase orders executed under short-term price agreements or at prevailing market rates. The amount invoiced reflects product, transportation and additional handling services as applicable, such as storage, transloading the product from railcars to trucks and last mile logistics to the customer site. We invoice most of our product customers on a per shipment basis, although for some larger customers, we consolidate invoices weekly or monthly. Standard collection terms are net 30 days, although extended terms are offered in competitive situations. We recognize revenue for products and materials at a point in time following the transfer of control of such items to the customer, which typically occurs upon shipment or delivery depending on the terms of the underlying contracts. We account for shipping and handling activities related to product and material sales contracts with customers as costs to fulfill our promise to transfer the associated products pursuant to the accounting policy election allowed under ASC 606-10-25-18b. Accordingly, we record amounts billed for shipping and handling costs as a component of net sales and accrue and classify related costs as a component of cost of sales at the time revenue is recognized. For a limited number of customers, we sell under long-term, minimum purchase supply agreements. These agreements define, among other commitments, the volume of product that our customers must purchase, the volume of product that we must provide and the price that we will charge and that our customers will pay for each product. Prices under these agreements are generally fixed and subject to certain contractual adjustments. Sometimes these agreements may undergo negotiations regarding pricing and volume requirements, which may often occur in volatile market conditions. While these negotiations continue, we may deliver product at prices or at volumes below the requirements in our existing supply agreements. An executed order specifying the type and quantity of product to be delivered, in combination with the noted agreements, comprise our contracts in these arrangements. Service We derive our service revenues primarily through the provision of transportation, equipment rental, and contract labor services to companies in the oil and gas industry. Transportation services typically consist of transporting customer proppant from storage facilities to proximal well-sites and are contracted through work orders executed under established pricing agreements. The amount invoiced reflects the transportation services rendered. Equipment rental services provide customers with use of either dedicated or nonspecific wellhead proppant delivery equipment solutions for contractual periods defined either through formal lease agreements or executed work orders under established pricing agreements. The amounts invoiced reflect the length of time the equipment set was utilized in the billing period. Contract labor services provide customers with proppant delivery equipment operators through work orders executed under established pricing agreements. The amounts invoiced reflect the amount of time our labor services were utilized in the billing period. We typically invoice our customers on a weekly or monthly basis; however, some customers receive invoices upon well-site operation completion. Standard collection terms are net 30 days, although extended terms are offered in competitive situations. We typically recognize revenue for specific, dedicated equipment set rental arrangements under ASC 842, Leases. For the remaining components of service revenue, we have applied the practical expedient allowed under ASC 606-10-55-18 to recognize transportation revenues in proportion to the amount we have the right to invoice. Contracts with Multiple Performance Obligations From time to time, we may enter into contracts that contain multiple performance obligations, such as work orders containing a combination of product, transportation, equipment rentals, and contract labor services. For these arrangements, we allocate the transaction price to each performance obligation identified in the contract based on relative standalone selling prices, or estimates of such prices, and recognize the related revenue as control of each individual product or service is transferred to the customer, in satisfaction of the corresponding performance obligations. We typically invoice our customers on a weekly or monthly basis; however, some customers receive invoices upon well-site operation completion. Standard collection terms are net 30 days, although extended terms are offered in competitive situations. Taxes Collected from Customers and Remitted to Governmental Authorities. We exclude from our measurement of transaction prices all taxes assessed by governmental authorities that are both (i) imposed on and concurrent with a specific revenue-producing transaction and (ii) collected from customers. Accordingly, such tax amounts are not included as a component of net sales or cost of sales. See Note S - Revenue. Deferred Revenues one
Unbilled Receivables	Unbilled ReceivablesRevenues recognized in advance of invoice issuance create assets referred to as “unbilled receivables.” Any portion of our unbilled receivables for which our right to consideration is conditional on a factor other than the passage of time is considered a contract asset. These assets are presented on a combined basis with accounts receivable and are converted to accounts receivable once billed.
Debt Issuance Costs	Debt Issuance CostsWe defer costs directly associated with acquiring third-party financing, primarily loan origination costs and related professional expenses. Debt issuance costs are deferred and amortized using the effective interest rate method over the term of our senior secured Term Loan facility and the straight-line method for our Revolver facility. Debt issuance costs related to long-term debt are reflected as a direct deduction from the carrying amount of the debt.
Employee Benefit Plans	Employee Benefit PlansWe provide a range of benefits to our employees and retired employees, including pensions and post-retirement healthcare and life insurance benefits. We record annual amounts relating to these plans based on calculations specified by generally accepted accounting principles, which include various actuarial assumptions, including discount rates, assumed rates of returns, compensation increases, turnover rates, mortality tables, and healthcare cost trend rates. We review the actuarial assumptions on an annual basis and make modifications to the assumptions based on current rates and trends when it is deemed appropriate to do so. As required by U.S. generally accepted accounting principles, the effect of the modifications is generally recorded or amortized over future periods. We believe that the assumptions utilized in recording our obligations under the plans are reasonable based on advice from our actuaries and information as to assumptions used by other employers.
Environmental Costs	Environmental Costs Environmental costs, other than qualifying capital expenditures, are accrued at the time the exposure becomes known and costs can be reasonably estimated. Costs are accrued based upon management’s estimates of all direct costs, after taking into account expected reimbursement by third parties (primarily the sellers of acquired businesses) and are reviewed by outside consultants. Environmental costs are charged to expense unless a settlement with an indemnifying party has been reached.
Self-Insurance	Self-InsuranceWe are self-insured for various levels of employee health insurance coverage, workers’ compensation and third-party product liability claims alleging occupational disease. We purchase insurance coverage for claim amounts which exceed our self-insured retentions. Depending on the type of insurance, these self-insured retentions range from $0.1 million to $0.5 million per occurrence. Our insurance reserves are accrued based on estimates of the ultimate cost of claims expected to occur during the covered period. These estimates are prepared with the assistance of outside actuaries and consultants. Our actuaries periodically review the volume and amount of claims activity, and based upon their findings, we adjust our insurance reserves accordingly. The ultimate cost of claims for a covered period may differ from our original estimates. The current portion of our self-insurance reserves is included in accrued liabilities and the non-current portion is included in other long-term obligations in our Balance Sheets.
Research and Development Costs	Research and Development Costs We may incur immaterial internal research and development (“R&D”) expenditures, and research and development conducted for others, all of which are expensed as incurred, and included in selling, general and administrative expense. R&D costs may include, but are not limited to, research and administrative salaries, contractor fees, building costs, utilities, administrative expenses, and allocations of corporate costs.
Advertising Costs	Advertising CostsWe recognize advertising expense when incurred as selling, general and administrative expense.
Equity-based Compensation	Equity-based Compensation We grant stock options, restricted stock, restricted stock units and performance share units to certain of our employees and directors under the Amended and Restated U.S. Silica Holdings, Inc. 2011 Incentive Compensation Plan. We recognize the cost of employee services rendered in exchange for awards of equity instruments. Vesting of restricted stock and restricted stock units is based on the individual continuing to render service over a pre-defined vesting schedule, generally three years. Cash dividend equivalents are accrued and paid to the holders of time-based restricted stock units and restricted stock. The fair value of the restricted stock awards is equal to the market price of our stock at date of grant. The restricted award-related compensation expense is recognized on a straight-line basis over the vesting period. We grant performance share units to certain employees in which the number of shares of common stock ultimately received is determined based on achievement of certain performance thresholds over a specified performance period (generally three years) in accordance with the stock award agreement. Cash dividend equivalents are not accrued or paid on performance share units. We recognize expense based on the estimated vesting of our performance share units granted and the grant date market price. The estimated vesting of the performance share units is principally based on the probability of achieving certain financial performance levels during the vesting periods. In the period it becomes probable that the minimum performance criteria specified in the award agreement will be achieved, we recognize expense for the proportionate share of the total fair value of the award related to the vesting period that has already lapsed. The remaining fair value of the award is expensed on a straight-line basis over the remaining vesting period. We grant certain employees performance share units, the vesting of which is based on our total shareholder return (“TSR”) ranking among a peer group over a three-year period. The number of units that will vest will depend on the percentage ranking of our TSR compared to the TSRs for each of the companies in the peer group over the performance period. For these awards subject to market conditions, a binomial-lattice model (i.e., Monte Carlo simulation model) is used to fair value these awards at grant date. The related compensation expense is recognized, on a straight-line basis, over the vesting period.
Income Taxes	Income Taxes Deferred taxes are recognized on the liability method whereby deferred tax assets are recognized for deductible temporary differences and operating loss and tax credit carry forwards and deferred tax liabilities are recognized for taxable temporary differences. This approach requires recognition of deferred tax liabilities and assets for the expected future tax consequences of events that have been included in the financial statements or tax returns. Under this method, deferred tax liabilities and assets are determined based upon the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the expenses are expected to reverse. Valuation allowances are provided if, based on the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. We recognize a tax benefit associated with an uncertain tax position when, in management’s judgment, it is more likely than not that the position will be sustained upon examination by a taxing authority. For a tax position that meets the more likely than not recognition threshold, we initially and subsequently measure the tax benefit as the largest amount that we judge to have a greater than 50% likelihood of being realized upon ultimate settlement with a taxing authority. The liability associated with unrecognized tax benefits is adjusted periodically due to changing circumstances, such as the progress of tax audits, case law developments and new or emerging legislation. Such adjustments are recognized entirely in the period in which they are identified. The effective tax rate includes the net impact of changes in the liability for unrecognized tax benefits and subsequent adjustments as considered appropriate by management.
Foreign Currency Translation	Foreign Currency Translation For our operations in countries where the functional currency is other than the U.S. dollar, balance sheet amounts are translated using the exchange rate in effect at the balance sheet date. Income statement amounts are translated monthly using the average exchange rate for the respective month. The gains and losses resulting from the changes in exchange rates from
Comprehensive Income (Loss)	Comprehensive Income (loss) In addition to net income (loss), comprehensive income (loss) includes all changes in equity during a period, such as adjustments to minimum pension liabilities.
Business Combinations	Business CombinationsWe account for business combinations using the acquisition method of accounting. Under this method, acquired assets, including separately identifiable intangible assets and any assumed liabilities, are recorded at their acquisition date estimated fair value. The excess of purchase price over the fair value amounts assigned to the assets acquired and liabilities assumed represents the goodwill amount resulting from the acquisition. Determining the fair value of assets acquired and liabilities assumed involves the use of significant estimates and assumptions.
New Accounting Pronouncements Recently Adopted and New Accounting Pronouncements Not Yet Adopted	New Accounting Pronouncements Recently Adopted In December 2019, the FASB issued Accounting Standards Update ("ASU") 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. The amendments in this Update simplified the accounting for income taxes by removing several exceptions and also simplified the accounting for income taxes by requiring that an entity recognize a franchise tax (or similar tax) that is partially based on income as an income-based tax and account for any incremental amount incurred as a non-income-based tax, requiring that an entity evaluate when a step up in the tax basis of goodwill should be considered part of the business combination in which the book goodwill was originally recognized and when it should be considered a separate transaction, specifying that an entity is not required to allocate the consolidated amount of current and deferred tax expense to a legal entity that is not subject to tax in its separate financial statements (however, an entity may elect to do so on an entity-by-entity basis) for a legal entity that is both not subject to tax and disregarded by the taxing authority, requiring that an entity reflect the effect of an enacted change in tax laws or rates in the annual effective tax rate computation in the interim period that includes the enactment date, and making minor codification improvements for income taxes related to employee stock ownership plans and investments in qualified affordable housing projects accounted for using the equity method. For public business entities, the amendments in this Update were effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. We adopted this guidance during the first quarter of 2021 and it did not have a material impact to our Consolidated Financial Statements. New Accounting Pronouncements Not Yet Adopted In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting followed by ASU 2021-01, Reference Rate Reform (Topic 848): Scope, issued in January 2021, to provide clarifying guidance regarding the scope of Topic 848. ASU 2020-04 was issued to provide optional guidance for a limited period of time to ease the potential burden in accounting for (or recognizing the effects of) reference rate reform on financial reporting. Generally, the guidance is to be applied as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020, or prospectively from a date within an interim period that includes or is subsequent to March 12, 2020, up to the date that the financial statements are available to be issued. ASU 2020-04 and ASU 2021-01 are effective for all entities through December 31, 2022. As of December 31, 2021, we have not elected to use the optional guidance and continue to evaluate the options provided by ASU 2020-04 and ASU 2021-01. See Note K - Debt for discussion of the use of the adjusted LIBOR rate in connection with borrowings under our senior secured revolving credit facility.
Fair Value Measurement	Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Fair value is estimated by applying the following hierarchy, which prioritizes the inputs used to measure fair value into three levels and bases the categorization within the hierarchy upon the lowest level of input that is available and significant to the fair value measurement: Level 1—Quoted prices in active markets for identical assets or liabilities. Level 2—Observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3—Inputs that are generally unobservable and typically reflect management’s estimate of assumptions that market participants would use in pricing the asset or liability. Cash Equivalents Due to the short-term maturity, we believe our cash equivalent instruments at December 31, 2021 and 2020, 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.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2021
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: In thousands, except per share amounts Year ended December 31, 2021 2020 2019 Numerator: Net loss attributable to U.S. Silica Holdings, Inc. $ (33,761) $ (114,094) $ (329,082) Denominator: Weighted average shares outstanding 74,350 73,634 73,253 Diluted effect of stock awards — — — Weighted average shares outstanding assuming dilution 74,350 73,634 73,253 Loss per share attributable to U.S. Silica Holdings, Inc.: Basic loss per share $ (0.45) $ (1.55) $ (4.49) Diluted loss per share $ (0.45) $ (1.55) $ (4.49)
Schedule of Antidilutive Securities Excluded from Computation of Diluted Earnings (Loss) Per Common Share	Certain stock options, restricted stock awards and performance share units were excluded from the computation of diluted earnings per share because their effect would have been anti-dilutive. Such potentially dilutive shares and stock awards (in thousands) excluded from the calculation of diluted earnings (loss) per common share were as follows: Year ended December 31, 2021 2020 2019 Potentially dilutive shares excluded 1,714 238 68 Stock options excluded 667 826 711 Restricted stock and performance share units awards excluded 66 3,435 1,298

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	12 Months Ended
	Dec. 31, 2021
Equity [Abstract]
Schedule of Changes in Accumulated Other Comprehensive Income (Loss)	The following table presents the changes in accumulated other comprehensive income (loss) by component (in thousands): For the Year Ended December 31, 2021 Foreign currency translation adjustments Pension and other post-retirement benefits liability Total Beginning Balance $ 583 $ (9,062) $ (8,479) Other comprehensive (loss) income before reclassifications (1,000) 9,035 8,035 Amounts reclassed from accumulated other comprehensive income — 793 793 Ending Balance $ (417) $ 766 $ 349

Accounts Receivable (Tables)

Accounts Receivable (Tables)	12 Months Ended
	Dec. 31, 2021
Receivables [Abstract]
Schedule of Accounts Receivable and Allowance for Doubtful Accounts	Accounts receivable (in thousands) consisted of the following: December 31, 2021 December 31, 2020 Trade receivables $ 182,992 $ 171,230 Less: Allowance for credit losses (5,248) (6,604) Net trade receivables 177,744 164,626 Other receivables (1) 25,015 42,308 Total accounts receivable $ 202,759 $ 206,934 (1) At December 31, 2021 and 2020, other receivables included $21.5 million and $37.4 million of refunds related to NOL carryback claims filed for various tax years in accordance with certain provisions of the CARES Act. The following table reflects the change of the allowance for credit losses (in thousands) disaggregated by portfolio segments: Oil & Gas Proppants Industrial & Specialty Products Total Beginning balance, December 31, 2020 $ 5,684 $ 920 $ 6,604 Allowance for credit losses (1,000) 545 (455) Write-offs (59) (842) (901) Ending balance, December 31, 2021 $ 4,625 $ 623 $ 5,248

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2021
Inventory Disclosure [Abstract]
Schedule of Inventories	Inventories (in thousands) consisted of the following: December 31, 2021 December 31, 2020 Supplies $ 45,605 $ 42,329 Raw materials and work in process 36,529 33,723 Finished goods 33,579 28,632 Total inventories $ 115,713 $ 104,684

Property, Plant and Mine Deve_2

Property, Plant and Mine Development (Tables)	12 Months Ended
	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Schedule of Property, Plant and Mine Development	Property, plant and mine development (in thousands) consisted of the following: December 31, 2021 December 31, 2020 Mining property and mine development $ 789,122 $ 788,287 Asset retirement cost 22,283 15,985 Land 55,541 54,710 Land improvements 76,248 76,002 Buildings 72,207 69,841 Machinery and equipment 1,189,548 1,171,382 Furniture and fixtures 3,932 4,071 Construction-in-progress 35,060 27,216 2,243,941 2,207,494 Accumulated depletion, depreciation, amortization and impairment charges (985,295) (839,402) Total property, plant and mine development, net $ 1,258,646 $ 1,368,092

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Changes in the Carrying Amount of Goodwill	The changes in the carrying amount of goodwill (in thousands) by business segment consisted of the following: Oil & Gas Proppants Segment Industrial & Specialty Products Segment Total Balance at December 31, 2019 $ 86,100 $ 187,424 $ 273,524 Impairment losses (86,100) — (86,100) EPMH acquisition adjustment (1) — (1,775) (1,775) Balance at December 31, 2020 — 185,649 185,649 Impairment losses — — — Balance at December 31, 2021 $ — $ 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 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: December 31, 2021 December 31, 2020 Gross Carrying Amount Accumulated Amortization Impairments Net Gross Carrying Amount Accumulated Amortization Impairments Net Technology and intellectual property $ 71,209 $ (25,069) $ (38) $ 46,102 $ 71,052 $ (18,854) $ (1,373) $ 50,825 Customer relationships 66,999 (27,987) — 39,012 66,999 (23,182) — 43,817 Total definite-lived intangible assets: $ 138,208 $ (53,056) $ (38) $ 85,114 $ 138,051 $ (42,036) $ (1,373) $ 94,642 Trade names 64,240 — — 64,240 65,390 — (1,150) 64,240 Other 700 — — 700 700 — — 700 Total intangible assets: $ 203,148 $ (53,056) $ (38) $ 150,054 $ 204,141 $ (42,036) $ (2,523) $ 159,582
Schedule of Changes in the Carrying Amount of Indefinite-Lived Intangible Assets	The changes in the carrying amount of intangible assets (in thousands) consisted of the following: December 31, 2021 December 31, 2020 Gross Carrying Amount Accumulated Amortization Impairments Net Gross Carrying Amount Accumulated Amortization Impairments Net Technology and intellectual property $ 71,209 $ (25,069) $ (38) $ 46,102 $ 71,052 $ (18,854) $ (1,373) $ 50,825 Customer relationships 66,999 (27,987) — 39,012 66,999 (23,182) — 43,817 Total definite-lived intangible assets: $ 138,208 $ (53,056) $ (38) $ 85,114 $ 138,051 $ (42,036) $ (1,373) $ 94,642 Trade names 64,240 — — 64,240 65,390 — (1,150) 64,240 Other 700 — — 700 700 — — 700 Total intangible assets: $ 203,148 $ (53,056) $ (38) $ 150,054 $ 204,141 $ (42,036) $ (2,523) $ 159,582
Schedule of Estimated Amortization Expense Related to Definite-Lived Intangible Assets	At December 31, 2021, the estimated amortization expense related to definite-lived intangible assets (in thousands) for the five succeeding years is as follows: 2022 $ 9,674 2023 $ 9,669 2024 $ 9,670 2025 $ 9,669 2026 $ 9,669

Accounts Payable and Accrued _2

Accounts Payable and Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2021
Payables and Accruals [Abstract]
Schedule of Accounts Payables and Accrued Liabilities	ccounts payable and accrued liabilities (in thousands) consisted of the following: December 31, 2021 2020 Trade payables $ 134,494 $ 90,564 Accrued salaries and wages 11,347 7,432 Accrued vacation liability 2,847 2,499 Current portion of liability for pension and post-retirement benefits 1,227 1,338 Accrued healthcare liability 1,619 1,886 Accrued property taxes and sales taxes 4,625 5,136 Vendor incentives — 4,782 Other accrued liabilities 11,511 8,283 Accounts payable and accrued liabilities $ 167,670 $ 121,920

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2021
Debt Disclosure [Abstract]
Schedule of Debt	Debt (in thousands) consisted of the following: December 31, 2021 December 31, 2020 Senior secured credit facility: Revolver expiring May 1, 2023 (4.13% at December 31, 2021 and 4.19% at December 31, 2020) $ — $ 25,000 Term Loan facility—final maturity May 1, 2025 (5.00% at December 31, 2021 and 5.00% December 31, 2020) 1,222,000 1,234,800 Less: Unamortized original issue discount (3,350) (4,376) Less: Unamortized debt issuance cost (15,200) (20,259) Insurance financing notes payable 4,424 4,187 Finance leases 3,546 350 Total debt 1,211,420 1,239,702 Less: current portion (18,285) (42,042) Total long-term portion of debt $ 1,193,135 $ 1,197,660
Schedule of Contractual Maturities of Debt	At December 31, 2021, contractual maturities of our senior secured Credit Facility (in thousands) are as follows: 2022 $ 12,800 2023 12,800 2024 12,800 2025 1,183,600 2026 — Thereafter — Total $ 1,222,000

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	12 Months Ended
	Dec. 31, 2021
Asset Retirement Obligation Disclosure [Abstract]
Schedule of Changes in Asset Retirement Obligations	Changes in the asset retirement obligations (in thousands) are as follows: December 31, 2021 December 31, 2020 Beginning balance $ 24,717 $ 25,825 Accretion 1,450 1,434 Additions and revisions of estimates 5,882 (2,542) Ending balance $ 32,049 $ 24,717

Equity-Based Compensation (Tabl

Equity-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2021
Share-based Payment Arrangement [Abstract]
Schedule of Stock Options Activity	The following table summarizes the status of, and changes in, our stock option awards: Number of Weighted Aggregate Intrinsic Value Weighted Outstanding at December 31, 2020 826,215 $ 29.05 $ — 3.1 years Granted — $ — $ — Exercised (10,164) $ 10.33 $ 44 Forfeited (113,333) $ 24.76 $ — Expired (36,000) $ 14.58 $ — Outstanding at December 31, 2021 666,718 $ 30.84 $ — 2.4 years Exercisable at December 31, 2021 666,718 $ 30.84 $ — 2.4 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: Number of Shares Grant Date Weighted Unvested, December 31, 2020 1,779,826 $ 6.22 Granted 881,261 $ 9.82 Vested (1,491,222) $ 6.44 Forfeited (25,555) $ 11.63 Unvested, December 31, 2021 1,144,310 $ 8.37 The following table summarizes the status of, and changes in, our performance share unit awards: Number of Shares Grant Date Weighted Unvested, December 31, 2020 1,513,648 $ 12.36 Granted 886,091 $ 12.04 Vested (292,241) $ 17.48 Forfeited/Cancelled (192,909) $ 29.10 Unvested, December 31, 2021 1,914,589 $ 9.77

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Annual Commitments	Future Minimum Annual Commitments (in thousands): Year ending December 31, Minimum Purchase Commitments 2022 $ 15,065 2023 10,386 2024 5,397 2025 2,886 2026 2,180 Thereafter 9,288 Total future purchase commitments $ 45,202

Pension and Post-Retirement B_2

Pension and Post-Retirement Benefits (Tables)	12 Months Ended
	Dec. 31, 2021
Retirement Benefits [Abstract]
Schedule of Net Pension Benefit Cost	Net pension benefit cost (in thousands) consisted of the following: Year Ended 2021 2020 2019 Service cost $ 2,855 $ 2,253 $ 1,304 Interest cost 2,619 4,037 5,375 Expected return on plan assets (5,688) (6,019) (6,171) Net amortization and deferral 3,212 3,127 1,648 Net pension benefit costs $ 2,998 $ 3,398 $ 2,156 Net post-retirement benefit cost (in thousands) consisted of the following: Year Ended December 31, 2021 2020 2019 Service cost $ 24 $ 70 $ 88 Interest cost 141 584 789 Unrecognized net (gain)/loss (2,204) — (29) Net post-retirement benefit costs $ (2,039) $ 654 $ 848
Schedule of Changes in Benefit Obligations and Plan Assets	The changes in benefit obligations and plan assets (in thousands), as well as the funded status (in thousands) of our pension and post-retirement plans were as follows: Pension Benefits Post-retirement Benefits 2021 2020 2021 2020 Benefit obligation at January 1, $ 157,198 $ 148,491 $ 11,318 $ 22,054 Service cost 2,855 2,253 24 70 Interest cost 2,619 4,037 141 584 Actuarial (gain) loss (6,637) 11,119 (3,193) 1,329 Benefits paid (9,551) (8,649) (680) (1,751) Other (2,233) (53) 1,781 (10,968) Benefit obligation at December 31, $ 144,251 $ 157,198 $ 9,391 $ 11,318 Fair value of plan assets at January 1, $ 120,563 $ 110,431 $ — $ — Actual return on plan assets 7,099 13,306 — — Employer contributions 2,800 5,475 579 1,335 Benefits paid (9,551) (8,649) (680) (1,751) Other — — 101 416 Fair value of plan assets at December 31, $ 120,911 $ 120,563 $ — $ — Plan assets less than benefit obligations at December 31 recognized as liability for pension and other post-retirement benefits $ (23,340) $ (36,635) $ (9,391) $ (11,318)
Schedule of Estimated Future Pension and Post-Retirement Benefit Payments	Future estimated annual benefit payments (in thousands) for pension and post-retirement benefit obligations were as follows: Benefits Post-retirement Pension Before After 2022 $ 9,526 $ 1,104 $ 1,104 2023 9,446 983 983 2024 9,539 911 911 2025 9,367 795 795 2026 9,271 742 742 2027-2031 43,405 2,775 2,775
Schedule of Weighted-Average Assumptions Used to Determine Benefit Obligations	The following weighted-average assumptions were used to determine our obligations under the plans: Pension Benefits Post-retirement Benefits 2021 2020 2021 2020 Discount rate 2.8 % 2.5 % 2.6 % 2.1 % Long-term rate of compensation increase N/A 3.0% N/A N/A Long-term rate of return on plan assets 5.8 % 6.3% N/A N/A Health care cost trend rate: Pre-65 initial rate/ultimate rate N/A N/A 6.2%/4.5% 6.5%/4.5% Pre-65 ultimate year N/A N/A 2028 2028 Post-65 initial rate/ultimate rate N/A N/A N/A/N/A 7.0%/4.5% Post-65 ultimate year N/A N/A N/A 2028
Schedule of Mortality Tables Used	Mortality tables used for pension benefits and post-retirement benefits plans were the following: Pension and Post-retirement Benefits 2021 2020 Healthy Lives Pri-2012 base mortality tables with generational mortality improvements using Scale MP-2021 Pri-2012 base mortality tables with generational mortality improvements using Scale MP-2020 Disabled Lives Pri-2012 base mortality tables with generational mortality improvements using Scale MP-2021 Pri-2012 base mortality tables with generational mortality improvements using Scale MP-2020
Schedule of Major Investments Categories and Their Relative Percentage of the Fair Value to Total Plan Assets	The major investment categories and their relative percentage of the fair value of total plan assets as invested were as follows: Pension Benefits Post-retirement Benefits (1) 2021 2020 2021 2020 Equity securities 51.6 % 57.9 % — % — % Debt securities 46.1 % 41.3 % — % — % Cash 2.3 % 0.8 % — % — % (1) Retiree health benefits are paid by the Company as covered expenses are incurred.
Schedule of Fair Value of Pension Plan Assets by Asset Category	The fair values of the pension plan assets (in thousands) at December 31, 2021, by asset category, were as follows: Level 1 Level 2 Level 3 Total Cash and cash equivalents $ — $ 2,743 $ — $ 2,743 Mutual funds: Diversified emerging markets 6,375 — — 6,375 Foreign large blend 21,719 — — 21,719 Large-cap blend 22,907 — — 22,907 Mid-cap blend 11,411 — — 11,411 Real estate — — — — Fixed income securities: Corporate notes and bonds 35,365 — — 35,365 U.S. Treasuries 6,915 — — 6,915 Mortgage-backed securities — 2,242 — 2,242 Asset-backed securities — 1,739 — 1,739 Real Assets — 9,495 — 9,495 Net asset $ 104,692 $ 16,219 $ — $ 120,911 The fair values of the pension plan assets (in thousands) at December 31, 2020, by asset category, were as follows: Level 1 Level 2 Level 3 Total Cash and cash equivalents $ — $ 1,020 $ — $ 1,020 Mutual funds: Diversified emerging markets 7,064 — — 7,064 Foreign large blend 22,638 — — 22,638 Large-cap blend 22,272 — — 22,272 Mid-cap blend 12,972 — — 12,972 Real estate 4,822 — — 4,822 Fixed income securities: Corporate notes and bonds 38,983 — — 38,983 U.S. Treasuries 8,582 — — 8,582 Mortgage-backed securities — 1,780 — 1,780 Asset-backed securities — 430 — 430 Net asset $ 117,333 $ 3,230 $ — $ 120,563
Schedule of Summary of Multiemployer Pension Plan	A summary of each multiemployer pension plan for which we participate is presented below: Pension EIN/ Pension Pension Protection Act Zone Status (1) FIP/RP Status Company Surcharge Expiration 2021 2020 2021 2020 2019 LIUNA 52-6074345/001 Green Green No $ 378 $ 361 $ 385 No 6/4/2022 IUOE 36-6052390/001 Green Green No 328 256 310 No 7/31/2022 CSSS (2) 36-6044243/001 Red Red Yes 51 51 51 NA NA (1) The Pension Protection Act of 2006 defines the zone status as follows: green—healthy, yellow—endangered, orange—seriously endangered and red—critical. (2) In 2011, we withdrew from the Central States, Southeast and Southwest Areas Pension Plan. The withdrawal liability of $1.0 million will be paid in monthly installments of $4,000 until 2031.

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2021
Leases [Abstract]
Schedule of Supplemental Balance Sheet Information	Supplemental balance sheet information related to leases (in thousands except for term and rate information) was as follows: Leases Classification December 31, 2021 December 31, 2020 Assets Operating Lease right-of-use assets $ 38,793 $ 37,130 Finance Lease right-of-use assets 3,448 339 Total leased assets $ 42,241 $ 37,469 Liabilities Current Operating Current portion of operating lease liabilities $ 14,469 $ 17,388 Finance Current portion of long-term debt 1,061 55 Non-Current Operating Operating lease liabilities 75,130 76,361 Finance Long-term debt, net 2,485 295 Total lease liabilities $ 93,145 $ 94,099 During 2020, we recorded impairment charges related to railcar leases, various equipment leases and an office building lease. These charges relate to the Oil & Gas Proppants segment and are recorded in "Goodwill and other asset impairments" in the Consolidated Statements of Operations. See Note W - Impairments for additional information. During the year ended 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 year ended December 31, 2020, we recorded a decrease to the ROU assets of $1.0 million and a decrease to the liability of $25.0 million. A gain of $24.0 million was recognized as operating income through cost of goods sold in our consolidated income statement for the year ended December 31, 2020. Operating lease liabilities are based on the net present value of the remaining lease payments over the remaining lease term. As most of our leases do not provide an implicit rate, in determining the lease liability and the present value of lease payments, we used our incremental borrowing rate based on the information available at the lease commencement date. The weighted average remaining lease term and discount rate related to leases were as follows: Lease Term and Discount Rate December 31, 2021 December 31, 2020 Weighted average remaining lease term: Operating leases 6.9 years 6.9 years Finance leases 3.6 years 2.9 years Weighted average discount rate: Operating leases 5.7 % 5.8 % Finance leases 5.1 % 5.0 %
Schedule of Components of Lease Expense and Supplemental Cash Flow Information	The components of lease expense included in our Consolidated Statements of Operations were as follows: Lease Costs Classification Year Ended Year Ended Operating lease costs (1) Cost of Sales $ 33,185 $ 26,548 Operating lease costs (2) Selling, general, and administrative 1,880 1,808 Right-of-use asset impairment Goodwill and other asset impairments — 3,406 Total (3) $ 35,065 $ 31,762 (1) Includes short-term operating lease costs of $17.9 million and $9.6 million for the years ended December 31, 2021 and 2020, respectively. (2) Includes short-term operating lease costs of $0.4 million and $0.4 million for the years ended December 31, 2021 and 2020, respectively. (3) Does not include expense of $0.8 million and $12 thousand for the years ended December 31, 2021 and 2020 for finance leases. Supplemental cash flow information related to leases was as follows: Year Ended December 31, 2021 Year Ended December 31, 2020 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows for operating leases $ 24,451 $ 62,140 Operating cash flows for finance leases $ 759 $ 12 Right-of-use assets obtained in exchange for new lease liabilities: Operating leases $ 17,350 $ 10,747 Finance leases $ 3,815 $ 359
Schedule of Maturity of Operating Lease Liabilities	Maturities of lease liabilities as of December 31, 2021: Maturities of lease liabilities Operating leases Finance leases 2022 $ 20,128 $ 1,209 2023 19,889 1,199 2024 16,441 764 2025 13,019 605 2026 11,116 71 Thereafter 30,642 — Total lease payments $ 111,235 $ 3,848 Less: Interest 17,939 302 Less: Other operating expenses 3,697 — Total $ 89,599 $ 3,546
Schedule of Maturities of Finance Lease Liabilities	Maturities of lease liabilities as of December 31, 2021: Maturities of lease liabilities Operating leases Finance leases 2022 $ 20,128 $ 1,209 2023 19,889 1,199 2024 16,441 764 2025 13,019 605 2026 11,116 71 Thereafter 30,642 — Total lease payments $ 111,235 $ 3,848 Less: Interest 17,939 302 Less: Other operating expenses 3,697 — Total $ 89,599 $ 3,546

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Schedule of Income before Income Tax, Domestic and Foreign	Income (loss) before income taxes (in thousands) consisted of the following: Year ended December 31, 2021 2020 2019 United States $ (48,328) $ (183,656) $ (435,918) Foreign 11,252 8,509 7,010 Total $ (37,076) $ (175,147) $ (428,908)
Schedule of Income Tax Benefit (Expense)	Income tax benefit (in thousands) consisted of the following: Year ended December 31, 2021 2020 2019 Current: Federal $ — $ — $ — State (3,353) (307) (1,188) Foreign (1,385) (1,473) (1,343) (4,738) (1,780) (2,531) Deferred: Federal 7,589 57,214 90,457 State (96) 4,591 11,225 Foreign — — — 7,493 61,805 101,682 Income tax benefit $ 2,755 $ 60,025 $ 99,151
Schedule of Effective Income Tax Rate on Pretax Earnings	Income tax benefit (in thousands) differed from the amount that would be provided by applying the U.S. federal statutory rate due to the following: Year ended December 31, 2021 2020 2019 Income tax benefit computed at U.S. federal statutory rate $ 7,786 $ 36,781 $ 90,070 Decrease (increase) resulting from: Statutory depletion 2,012 1,230 4,679 Prior year tax return reconciliation (2,490) (2,084) 3,121 State income taxes, net of federal benefit 445 5,013 9,486 Unrecognized tax benefits (1,302) — — Adjustment to deferred taxes from the CARES Act — 22,318 — Equity compensation (627) (1,477) (6,440) Executive compensation (2,092) (579) (722) Other, net (977) (1,177) (1,043) Income tax benefit $ 2,755 $ 60,025 $ 99,151
Schedule of Tax Effects on Deferred Tax Assets and Liabilities	The tax effects of the types of temporary differences and carry forwards that gave rise to deferred tax assets and liabilities (in thousands) consisted of the following: December 31, 2021 2020 Gross deferred tax assets: Net operating loss carry forward and state tax credits $ 77,327 $ 90,087 Pension and post-retirement benefit costs 7,318 11,146 Property, plant and equipment 8,619 6,866 Accrued expenses 14,930 12,397 Inventories 1,200 121 Federal tax credits 4,188 4,188 Stock-based compensation expense 4,359 4,307 Interest expense limitation 16,921 14,127 Intangibles 7,876 11,304 Lease obligation liability 13,297 14,154 Other 4,399 5,286 Total deferred tax assets 160,434 173,983 Gross deferred tax liabilities: Land and mineral property basis difference (121,211) (122,265) Fixed assets and depreciation (83,708) (100,640) Other (289) (464) Total deferred tax liabilities (205,208) (223,369) Net deferred tax liabilities $ (44,774) $ (49,386)
Schedule of Unrecognized Tax Benefits Roll Forward	The following table is a reconciliation of our unrecognized tax benefits: Year ended December 31, 2021 2020 2019 Balance as of January 1 $ — $ — $ — Additions for tax positions of prior years 856 — — Balance as of December 31 $ 856 $ — $ —

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Dec. 31, 2021
Revenue from Contract with Customer [Abstract]
Schedule of Sales by Major Source	The following table reflects our sales disaggregated by major source (in thousands): Year Ended December 31, 2021 Year Ended December 31, 2020 Category Oil & Gas Proppants Industrial & Specialty Products Total Sales Oil & Gas Proppants Industrial & Specialty Products Total Sales Product $ 407,772 $ 488,431 $ 896,203 $ 301,199 $ 430,988 $ 732,187 Service 207,676 — 207,676 113,698 — 113,698 Total Sales $ 615,448 $ 488,431 $ 1,103,879 $ 414,897 $ 430,988 $ 845,885
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 (in thousands): Unbilled Receivables December 31, 2021 December 31, 2020 Beginning Balance $ 47,982 $ 20,144 Reclassifications to billed receivables (105,305) (10,330) Revenues recognized in excess of period billings 59,280 38,168 Ending Balance $ 1,957 $ 47,982 We enter into certain customer supply agreements which give the customers the right to purchase certain products for a discounted price at certain volumes over an average initial contract term of one Deferred Revenue December 31, 2021 December 31, 2020 Beginning Balance $ 33,692 $ 50,634 Revenues recognized from balances held at the beginning of the period (13,172) (19,704) Revenues deferred from period collections on unfulfilled performance obligations 5,207 6,627 Revenues recognized from period collections (4,986) (3,865) Ending Balance $ 20,741 $ 33,692
Schedule of Information Related to Foreign Operations	The following table includes information related to our foreign operations (in thousands): For the years ended December 31, 2021 December 31, 2020 December 31, 2019 Total Sales $ 96,317 $ 86,179 $ 92,788 Pre-tax income $ 11,252 $ 8,509 $ 7,010 Net income $ 8,889 $ 6,722 $ 5,538

Segment Reporting (Tables)

Segment Reporting (Tables)	12 Months Ended
	Dec. 31, 2021
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 reported segments for the years ended December 31, 2021, 2020 and 2019: Year Ended 2021 2020 2019 Sales: Oil & Gas Proppants $ 615,448 $ 414,897 $ 1,010,521 Industrial & Specialty Products 488,431 430,988 463,956 Total sales 1,103,879 845,885 1,474,477 Segment contribution margin: Oil & Gas Proppants 160,052 142,041 248,594 Industrial & Specialty Products 168,499 159,176 178,215 Total segment contribution margin 328,551 301,217 426,809 Operating activities excluded from segment cost of sales (19,655) (30,402) (85,625) Selling, general and administrative (119,628) (124,171) (150,848) Depreciation, depletion and amortization (161,131) (155,568) (179,444) Goodwill and other asset impairments (202) (110,688) (363,847) Interest expense (71,157) (79,885) (95,472) Other income, net, including interest income 6,146 24,350 19,519 Income tax benefit 2,755 60,025 99,151 Net loss $ (34,321) $ (115,122) $ (329,757) Less: Net loss attributable to non-controlling interest (560) (1,028) (675) Net loss attributable to U.S. Silica Holdings, Inc. $ (33,761) $ (114,094) $ (329,082)

Parent Company Financials (Tabl

Parent Company Financials (Tables)	12 Months Ended
	Dec. 31, 2021
Condensed Financial Information Disclosure [Abstract]
Condensed Balance Sheets	U.S. SILICA HOLDINGS, INC. (PARENT COMPANY ONLY) CONDENSED BALANCE SHEETS December 31, 2021 2020 (in thousands) ASSETS Current Assets: Cash and cash equivalents $ 46,996 $ 46,851 Due from affiliates 165,632 168,276 Total current assets 212,628 215,127 Investment in subsidiaries 401,691 412,169 Total assets $ 614,319 $ 627,296 LIABILITIES AND STOCKHOLDERS’ EQUITY Current Liabilities: Accrued expenses and other current liabilities $ 50 $ 286 Dividends payable 186 219 Total current liabilities 236 505 Total liabilities 236 505 Stockholders’ Equity: Preferred stock — — Common stock 845 827 Additional paid-in capital 1,218,575 1,200,023 Retained deficit (429,260) (395,496) Treasury stock, at cost (186,294) (181,615) Accumulated other comprehensive income (loss) 349 (8,479) Total U.S. Silica Holdings, Inc. stockholders’ equity 604,215 615,260 Non-controlling interest 9,868 11,531 Total stockholders' equity 614,083 626,791 Total liabilities and stockholders’ equity $ 614,319 $ 627,296
Condensed Statements of Operations and Comprehensive Income (Loss)	U.S. SILICA HOLDINGS, INC. (PARENT COMPANY ONLY) CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) Year ended December 31, 2021 2020 2019 (in thousands) Sales $ — $ — $ — Cost of sales — — — Operating expenses Selling, general and administrative 252 253 253 Total operating expenses 252 253 253 Operating loss (252) (253) (253) Other income (expense) Interest income 5 210 1,440 Total other income 5 210 1,440 (Loss) income before income taxes and equity in net earnings of subsidiaries (247) (43) 1,187 Income tax expense — — (327) (Loss) income before equity in net earnings of subsidiaries (247) (43) 860 Equity in earnings of subsidiaries, net of tax (34,074) (115,079) (330,617) Net loss (34,321) (115,122) (329,757) Less: Net loss attributable to non-controlling interest (560) (1,028) (675) Net loss attributable to U.S. Silica Holdings, Inc. (33,761) (114,094) (329,082) Net loss (34,321) (115,122) (329,757) Other comprehensive (loss) income Unrealized gain (loss) on derivatives (net of tax of $—, $973, and $(456) for 2021, 2020, and 2019, respectively) — 3,053 (1,432) Foreign currency translation adjustment (net of tax of $(309), $444, and $(60) for 2021, 2020 and 2019, respectively) (1,000) 1,391 (188) Pension and other post-retirement benefits liability adjustment (net of tax of $3,131, $2,207, and $(1,024) for 2021, 2020 and 2019, respectively) 9,828 6,931 (3,214) Comprehensive loss (25,493) (103,747) (334,591) Less: Comprehensive loss attributable to non-controlling interest (560) (1,028) (675) Comprehensive loss attributable to U.S. Silica Holdings, Inc. (24,933) (102,719) (333,916)
Condensed Statements of Stockholders' Equity	U.S. SILICA HOLDINGS, INC. (PARENT COMPANY ONLY) CONDENSED STATEMENTS OF STOCKHOLDERS' EQUITY (amounts in thousands) Par Value Treasury Stock Additional Paid-In Capital Retained Earnings (Deficit) - Present Accumulated Other Comprehensive (Loss) Income Total U.S. Silica, Inc. Stockholders' Equity Non-controlling Interest Total Balance at January 1, 2019 $ 818 $ (178,215) $ 1,169,383 $ 67,854 $ (15,020) $ 1,044,820 $ 7,484 $ 1,052,304 Net loss — — — (329,082) — (329,082) (675) (329,757) Unrealized loss on derivatives — — — — (1,432) (1,432) — (1,432) Foreign currency translation adjustment — — — — (188) (188) — (188) Pension and post-retirement liability — — — — (3,214) (3,214) — (3,214) Cash dividend declared ($0.25 per share) — — — (18,728) — (18,728) — (18,728) Contributions from non-controlling interest — — — — — — 4,554 4,554 Common stock-based compensation plans activity: Equity-based compensation — — 15,906 — — 15,906 — 15,906 Proceeds from options exercised — 296 (168) — — 128 — 128 Shares withheld for employee taxes related to vested restricted stock and stock units 5 (2,993) (5) — — (2,993) — (2,993) Balance at December 31, 2019 $ 823 $ (180,912) $ 1,185,116 $ (279,956) $ (19,854) $ 705,217 $ 11,363 $ 716,580 Net loss — — — (114,094) — (114,094) (1,028) (115,122) Unrealized gain on derivatives — — — — 3,053 3,053 — 3,053 Foreign currency translation adjustment — — — — 1,391 1,391 — 1,391 Pension and post-retirement liability — — — — 6,931 6,931 — 6,931 Cash dividend declared ($0.02 per share) — — — (1,446) — (1,446) — (1,446) Contributions from non-controlling interest — — — — — — 1,196 1,196 Common stock-based compensation plans activity: Equity-based compensation — — 14,911 — — 14,911 — 14,911 Shares withheld for employee taxes related to vested restricted stock and stock units 4 (703) (4) — — (703) — (703) Balance at December 31, 2020 $ 827 $ (181,615) $ 1,200,023 $ (395,496) $ (8,479) $ 615,260 $ 11,531 $ 626,791 Net loss — — — (33,761) — (33,761) (560) (34,321) Foreign currency translation adjustment — — — — (1,000) (1,000) — (1,000) Pension and post-retirement liability — — — — 9,828 9,828 — 9,828 Cash dividends — — — (3) — (3) — (3) Distributions to non-controlling interest — — — — — — (1,103) (1,103) Common stock-based compensation plans activity: Equity-based compensation — — 18,809 — — 18,809 — 18,809 Proceeds from options exercised — 344 (239) — — 105 — 105 Shares withheld for employee taxes related to vested restricted stock and stock units 18 (5,023) (18) — — (5,023) — (5,023) Balance at December 31, 2021 $ 845 $ (186,294) $ 1,218,575 $ (429,260) $ 349 $ 604,215 $ 9,868 $ 614,083
Condensed Statements of Cash Flows	U.S. SILICA HOLDINGS, INC. (PARENT COMPANY ONLY) CONDENSED STATEMENTS OF CASH FLOWS Year ended December 31, 2021 2020 2019 (in thousands) Operating activities: Net loss $ (34,321) $ (115,122) $ (329,757) Adjustments to reconcile net (loss) income to net cash provided by operating activities: Undistributed loss from equity method investment, net 34,074 115,079 330,617 Changes in assets and liabilities, net of effects of acquisitions: Accounts payable and accrued liabilities (236) 155 (88) Net cash (used in) provided by operating activities (483) 112 772 Investing activities: Investment in subsidiary — — — Net cash used in investing activities — — — Financing activities: Dividends paid (26) (6,185) (18,592) Proceeds from options exercised 105 — 128 Tax payments related to shares withheld for vested restricted stock and stock units (5,023) (703) (2,993) (Distributions to) contributions from non-controlling interest (1,103) 1,196 4,554 Net financing activities with subsidiaries 6,675 582 (39,171) Net cash provided by (used in) financing activities 628 (5,110) (56,074) Net increase (decrease) in cash and cash equivalents 145 (4,998) (55,302) Cash and cash equivalents, beginning of period 46,851 51,849 107,151 Cash and cash equivalents, end of period $ 46,996 $ 46,851 $ 51,849 Supplemental cash flow information: Cash received during the period for: Interest $ (17) $ (210) $ (1,440)

Impairments (Tables)

Impairments (Tables)	12 Months Ended
	Dec. 31, 2021
Disclosure Text Block Supplement [Abstract]
Schedule of Asset Impairment Charges	We recorded impairment charges (in thousands) for the following assets: Description December 31, 2021 December 31, 2020 December 31, 2019 Inventories, net $ — $ 6,837 $ 4,100 Property, plant and mine development, net 164 11,822 243,064 Operating lease right-of-use assets — 3,406 115,443 Goodwill — 86,100 — Intangible assets, net 38 2,523 1,240 Total $ 202 $ 110,688 $ 363,847

Organization (Details)

Organization (Details)	12 Months Ended
	Dec. 31, 2021Segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of business segments	2

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percent or reporting unit fair value less than carrying value	50.00%
Amortization of debt issuance costs and discounts included in interest expense	$ 5.1	$ 5.1	$ 5.6
Self-insurance reserves	5.8	6.2
Self-insurance reserves classified as current	$ 2.1	$ 2.4
Restricted Stock and Restricted Stock Units
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Vesting period for awards of equity instruments	3 years
Performance Share Units
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Vesting period for awards of equity instruments	3 years
Performance Share Units | Certain Employees
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Vesting period for awards of equity instruments		3 years
Intellectual property
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful live of finite-lived intangible assets	15 years
Buildings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful lives of property, plant and mine equipment	15 years
Land improvements
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful lives of property, plant and mine equipment	10 years
Furniture and fixtures
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful lives of property, plant and mine equipment	8 years
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Self-insurance retention amount	$ 0.1
Minimum | Supply Agreement
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred revenue, average initial contract term	1 year
Minimum | Customer relationships
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful live of finite-lived intangible assets	13 years
Minimum | Machinery and equipment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful lives of property, plant and mine equipment	3 years
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Self-insurance retention amount	$ 0.5
Maximum | Supply Agreement
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred revenue, average initial contract term	15 years
Maximum | Customer relationships
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful live of finite-lived intangible assets	20 years
Maximum | Machinery and equipment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful lives of property, plant and mine equipment	10 years

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	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Numerator:
Net loss attributable to U.S. Silica Holdings, Inc.	$ (33,761)	$ (114,094)	$ (329,082)
Denominator:
Weighted average shares outstanding, basic (in shares)	74,350	73,634	73,253
Diluted effect of stock awards (in shares)	0	0	0
Weighted average shares outstanding assuming dilution (in shares)	74,350	73,634	73,253
Loss per share attributable to U.S. Silica Holdings, Inc.:
Basic loss per share (in dollars per share)	$ (0.45)	$ (1.55)	$ (4.49)
Diluted loss per share (in dollars per share)	$ (0.45)	$ (1.55)	$ (4.49)

Earnings Per Share - Antidiluti

Earnings Per Share - Antidilutive Securities Excluded From Calculation of Diluted Earnings (Loss) Per Common Share (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Potentially dilutive shares excluded
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from the calculation of diluted earnings (loss) per common share (shares)	1,714	238	68
Stock options excluded
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from the calculation of diluted earnings (loss) per common share (shares)	667	826	711
Restricted stock and performance share units awards excluded
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from the calculation of diluted earnings (loss) per common share (shares)	66	3,435	1,298

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Income (Loss) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021USD ($)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	$ 626,791
Ending Balance	614,083
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	583
Other comprehensive (loss) income before reclassifications	(1,000)
Amounts reclassed from accumulated other comprehensive income	0
Ending Balance	(417)
Pension and other post-retirement benefits liability
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(9,062)
Other comprehensive (loss) income before reclassifications	9,035
Amounts reclassed from accumulated other comprehensive income	793
Ending Balance	766
Total
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(8,479)
Other comprehensive (loss) income before reclassifications	8,035
Amounts reclassed from accumulated other comprehensive income	793
Ending Balance	$ 349

Business Combinations - Narrati

Business Combinations - Narrative (Details) - Arrows Up LLC - SandBox Logistics - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Business Acquisition [Line Items]
Consideration paid		$ 0
Fair value of assets acquired		20,100,000
Fair value of liabilities assumed		2,500,000
Gain on bargain purchase recognized		$ 17,600,000
Increase in accounts receivable	$ 100,000
Net decrease to initial gain on bargain purchase	$ 2,400,000

Accounts Receivable (Details)

Accounts Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Receivables [Abstract]
Trade receivables	$ 182,992	$ 171,230
Less: Allowance for credit losses	(5,248)	(6,604)
Net trade receivables	177,744	164,626
Other receivables	25,015	42,308
Total accounts receivable	202,759	206,934
Net NOL carryback claims receivable under CARES Act	$ 21,500	$ 37,400

Accounts Receivable - Allowance

Accounts Receivable - Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Allowance for Doubtful Accounts Receivable Roll Forward
Beginning balance, December 31, 2020	$ 6,604
Allowance for credit losses	(455)	$ 1,510	$ 3,466
Write-offs	(901)
Ending balance, December 31, 2021	5,248	6,604
Oil & Gas Proppants
Allowance for Doubtful Accounts Receivable Roll Forward
Beginning balance, December 31, 2020	5,684
Allowance for credit losses	(1,000)
Write-offs	(59)
Ending balance, December 31, 2021	4,625	5,684
Industrial & Specialty Products
Allowance for Doubtful Accounts Receivable Roll Forward
Beginning balance, December 31, 2020	920
Allowance for credit losses	545
Write-offs	(842)
Ending balance, December 31, 2021	$ 623	$ 920

Accounts Receivable - Narrative

Accounts Receivable - Narrative (Details) - Customer Concentration Risk	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Sales | Ten Largest Customers
Concentration Risk [Line Items]
Concentration risk percentage	40.00%	34.00%	43.00%
Sales | One Customer
Concentration Risk [Line Items]
Concentration risk percentage			11.00%
Trade Accounts Receivables | One Customer
Concentration Risk [Line Items]
Concentration risk percentage		24.00%

Inventories (Details)

Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Inventory Disclosure [Abstract]
Supplies	$ 45,605	$ 42,329
Raw materials and work in process	36,529	33,723
Finished goods	33,579	28,632
Total inventories	$ 115,713	$ 104,684

Property, Plant and Mine Deve_3

Property, Plant and Mine Development (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment
Property, plant and mine development, gross	$ 2,243,941	$ 2,207,494
Accumulated depletion, depreciation, amortization and impairment charges	(985,295)	(839,402)
Total property, plant and mine development, net	1,258,646	1,368,092
Mining property and mine development
Property, Plant and Equipment
Property, plant and mine development, gross	789,122	788,287
Asset retirement cost
Property, Plant and Equipment
Property, plant and mine development, gross	22,283	15,985
Land
Property, Plant and Equipment
Property, plant and mine development, gross	55,541	54,710
Land improvements
Property, Plant and Equipment
Property, plant and mine development, gross	76,248	76,002
Buildings
Property, Plant and Equipment
Property, plant and mine development, gross	72,207	69,841
Machinery and equipment
Property, Plant and Equipment
Property, plant and mine development, gross	1,189,548	1,171,382
Furniture and fixtures
Property, Plant and Equipment
Property, plant and mine development, gross	3,932	4,071
Construction-in-progress
Property, Plant and Equipment
Property, plant and mine development, gross	$ 35,060	$ 27,216

Property, Plant and Mine Deve_4

Property, Plant and Mine Development - Narrative (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment
Depreciation expense		$ 149,600,000	$ 143,800,000
Disposal Group, Held-for-sale, Not Discontinued Operations | Land
Property, Plant and Equipment
Impairment recognized on assets held for sale			0
Disposal Group, Held-for-sale, Not Discontinued Operations | Land | Prepaid expenses and other current assets
Property, Plant and Equipment
Assets held for sale	$ 3,200,000		$ 3,200,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Land
Property, Plant and Equipment
Gain on sale of assets	$ 300,000

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Changes in Carrying Amount of Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Roll Forward]
Beginning balance	$ 273,524	$ 185,649	$ 273,524
Impairment losses		0	(86,100)	$ 0
Ending balance		185,649	185,649	273,524
EPMH
Goodwill [Roll Forward]
EPMH acquisition adjustment			(1,775)
Oil & Gas Proppants
Goodwill [Roll Forward]
Beginning balance	86,100	0	86,100
Impairment losses		0	(86,100)
Ending balance		0	0	86,100
Oil & Gas Proppants | EPMH
Goodwill [Roll Forward]
EPMH acquisition adjustment			0
Industrial & Specialty Products
Goodwill [Roll Forward]
Beginning balance	187,424	185,649	187,424
Impairment losses		0	0
Ending balance		$ 185,649	185,649	$ 187,424
Industrial & Specialty Products | EPMH
Goodwill [Roll Forward]
EPMH acquisition adjustment			$ (1,775)
Reclassification of goodwill	$ (1,800)

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Narrative (Details) - USD ($)	3 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill impairment		$ 0	$ 86,100,000	$ 0
Amortization expense		$ 9,700,000	10,300,000	10,800,000
Technology and intellectual property
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated useful live of finite-lived intangible assets		15 years
Oil & Gas Proppants
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill impairment		$ 0	86,100,000
Capitalized legal fees related to unsuccessful defense of patents	$ 11,800,000
Oil & Gas Proppants
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill impairment		$ 86,100,000	$ 0	$ 0
Maximum | Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated useful live of finite-lived intangible assets		20 years
Minimum | Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated useful live of finite-lived intangible assets		13 years

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Changes in the Carrying Amount of Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets
Gross Carrying Amount	$ 138,208	$ 138,051
Accumulated Amortization	(53,056)	(42,036)
Impairments	(38)	(1,373)
Net	85,114	94,642
Total Intangible Assets
Gross Carrying Amount	203,148	204,141
Accumulated Amortization	(53,056)	(42,036)
Impairments	(38)	(2,523)
Net	150,054	159,582
Trade names
Indefinite-lived Intangible Assets
Gross Carrying Amount	64,240	65,390
Impairments	0	(1,150)
Net	64,240	64,240
Other
Indefinite-lived Intangible Assets
Gross Carrying Amount	700	700
Impairments	0	0
Net	700	700
Technology and intellectual property
Finite-Lived Intangible Assets
Gross Carrying Amount	71,209	71,052
Accumulated Amortization	(25,069)	(18,854)
Impairments	(38)	(1,373)
Net	46,102	50,825
Total Intangible Assets
Accumulated Amortization	(25,069)	(18,854)
Customer relationships
Finite-Lived Intangible Assets
Gross Carrying Amount	66,999	66,999
Accumulated Amortization	(27,987)	(23,182)
Impairments	0	0
Net	39,012	43,817
Total Intangible Assets
Accumulated Amortization	$ (27,987)	$ (23,182)

Goodwill and Intangible Asset_5

Goodwill and Intangible Assets - Estimated Amortization Expense Related to Definite-Lived Intangible Assets (Details) $ in Thousands	Dec. 31, 2021USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2022	$ 9,674
2023	9,669
2024	9,670
2025	9,669
2026	$ 9,669

Accounts Payable and Accrued _3

Accounts Payable and Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Payables and Accruals [Abstract]
Trade payables	$ 134,494	$ 90,564
Accrued salaries and wages	11,347	7,432
Accrued vacation liability	2,847	2,499
Current portion of liability for pension and post-retirement benefits	1,227	1,338
Accrued healthcare liability	1,619	1,886
Accrued property taxes and sales taxes	4,625	5,136
Vendor incentives	0	4,782
Other accrued liabilities	11,511	8,283
Accounts payable and accrued liabilities	$ 167,670	$ 121,920

Debt - Schedule of Debt (Detail

Debt - Schedule of Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Line of Credit Facility
Less: Unamortized original issue discount	$ (3,350)	$ (4,376)
Less: Unamortized debt issuance cost	(15,200)	(20,259)
Finance leases	3,546	350
Total debt	1,211,420	1,239,702
Less: current portion	(18,285)	(42,042)
Total long-term portion of debt	1,193,135	1,197,660
Notes Payable | Insurance financing notes payable
Line of Credit Facility
Insurance financing notes payable	$ 4,424	$ 4,187
Revolving Credit Facility | Revolver expiring May 1, 2023 (4.13% at December 31, 2021 and 4.19% at December 31, 2020)
Line of Credit Facility
Credit facility, interest rate	4.13%	4.19%
Long-term debt	$ 0	$ 25,000
Senior Secured Credit Facility | Term Loan facility—final maturity May 1, 2025 (5.00% at December 31, 2021 and 5.00% December 31, 2020)
Line of Credit Facility
Credit facility, interest rate	5.00%	5.00%
Long-term debt	$ 1,222,000	$ 1,234,800

Debt - Narrative (Details)

Debt - Narrative (Details)	May 01, 2018USD ($)	Sep. 30, 2021	Dec. 31, 2020USD ($)payment	Dec. 31, 2021USD ($)
Insurance financing notes payable | Notes Payable
Debt Instrument [Line Items]
Debt stated interest rate		2.90%
Debt term		9 months
Notes payable balance			$ 4,187,000	$ 4,424,000
Senior Secured Credit Facility | Term Loan
Debt Instrument [Line Items]
Credit facility consolidated total net leverage ratio	3.75
Senior Secured Credit Facility | Revolver
Debt Instrument [Line Items]
Net leverage ratio, credit facility threshold percentage	30.00%
Revolving Credit Facility | Revolver
Debt Instrument [Line Items]
Available borrowing base				100,000,000
Amount drawn under credit facility				0
Amount available under credit facility				77,800,000
Letter of Credit | Revolver
Debt Instrument [Line Items]
Amount allocated for letters of credit				$ 22,200,000
Current consolidated leverage ratio				5.41
Current borrowing capacity under credit facility without consent of lenders				$ 30,000,000
Senior Secured Credit Facility
Debt Instrument [Line Items]
Debt issued	$ 1,380,000,000
Senior Secured Credit Facility | Term Loan
Debt Instrument [Line Items]
Debt issued	1,280,000,000
Senior Secured Credit Facility | Revolving Credit Facility | Revolver
Debt Instrument [Line Items]
Available borrowing base	100,000,000
Capitalized debt issuance costs	$ 38,700,000
Notes Payable | Note Payable Secured by Royalty Interest
Debt Instrument [Line Items]
Number of debt settlement payments | payment			1
Debt settlement			$ 2,550,000
Accrued royalties			0
Gain on extinguishment of debt			$ 8,300,000

Debt - Contractual Maturities o

Debt - Contractual Maturities of Senior Secured Credit Facility (Details) - Senior Secured Credit Facility - Term Loan - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
2022	$ 12,800
2023	12,800
2024	12,800
2025	1,183,600
2026	0
Thereafter	0
Total	$ 1,222,000	$ 1,234,800

Asset Retirement Obligations -

Asset Retirement Obligations - Schedule of Changes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance	$ 24,717	$ 25,825
Accretion	1,450	1,434
Additions and revisions of estimates	5,882	(2,542)
Ending balance	$ 32,049	$ 24,717

Equity-Based Compensation - Nar

Equity-Based Compensation - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted (in shares)	0	0	0
Stock options exercised (in shares)	10,164	0	10,000
Exercised	$ 44,000	$ 0	$ 12,000
Proceeds from options exercised	105,000	0	128,000
Tax benefit realized from stock options exercised	11,000	0	3,000
Unrecognized compensation expense related to stock options	$ 0	$ 0	$ 0
Restricted Stock and Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards share units granted (in shares)	881,261	1,590,170	814,387
Recognized equity-based compensation	$ 7,300,000	$ 8,100,000	$ 8,200,000
Unrecognized compensation expense related to awards	$ 7,500,000
Recognized weighted-average period	1 year 8 months 12 days
Vesting period for awards of equity instruments	3 years
Grant date fair value of awards granted (in dollars per share)	$ 9.82
Restricted Stock and Restricted Stock Units to be Settled in Cash
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized equity-based compensation	$ 900,000	$ 600,000
Unrecognized compensation expense related to awards	$ 800,000
Recognized weighted-average period	1 year 1 month 6 days
Vesting period for awards of equity instruments		3 years
Performance Share Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards share units granted (in shares)	886,091	1,020,161	607,130
Recognized equity-based compensation	$ 11,500,000	$ 6,800,000	$ 7,700,000
Unrecognized compensation expense related to awards	$ 10,000,000
Recognized weighted-average period	1 year 7 months 6 days
Vesting period for awards of equity instruments	3 years
Grant date fair value of awards granted (in dollars per share)	$ 12.04	$ 6.57	$ 15.58
Performance Shares to be Settled in Cash
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized equity-based compensation	$ 700,000	$ 900,000
Unrecognized compensation expense related to awards	$ 600,000
Recognized weighted-average period	1 year 1 month 6 days
Vesting period for awards of equity instruments	3 years
2011 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock that may be issued (in shares)	3,852,762

Equity-Based Compensation - Sto

Equity-Based Compensation - Stock Options Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Number of Shares
Outstanding at December 31, 2020 (in shares)	826,215
Granted (in shares)	0	0	0
Exercised (in shares)	(10,164)	0	(10,000)
Forfeited (in shares)	(113,333)
Expired (in shares)	(36,000)
Outstanding at December 31, 2021 (in shares)	666,718	826,215
Exercisable at December 31, 2021 (in shares)	666,718
Weighted Average Exercise Price
Outstanding at December 31, 2020, (in dollars per share)	$ 29.05
Granted (in dollars per share)	0
Exercised (in dollars per share)	10.33
Forfeited (in dollars per share)	24.76
Expired (in dollars per share)	14.58
Outstanding at December 31, 2021, (in dollars per share)	30.84	$ 29.05
Exercisable at December 31, 2021 (in dollars per share)	$ 30.84
Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2020	$ 0
Exercised	44	$ 0	$ 12
Outstanding at December 31, 2021	0	$ 0
Exercisable at December 31, 2021	$ 0
Weighted Average Remaining Contractual Term in Years
Outstanding at December 31, 2020	2 years 4 months 24 days	3 years 1 month 6 days
Outstanding at December 31, 2021	2 years 4 months 24 days	3 years 1 month 6 days
Exercisable at December 31, 2021	2 years 4 months 24 days

Equity-Based Compensation - Res

Equity-Based Compensation - Restricted Stock and Restricted Stock Units Activity (Details) - Restricted Stock and Restricted Stock Units - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Number of Shares
Unvested, December 31, 2020 (in shares)	1,779,826
Granted (in shares)	881,261	1,590,170	814,387
Vested (in shares)	(1,491,222)
Forfeited (in shares)	(25,555)
Unvested, December 31, 2021 (in shares)	1,144,310	1,779,826
Grant Date Weighted Average Fair Value
Unvested, December 31, 2020 (in dollars per share)	$ 6.22
Granted (in dollars per share)	9.82
Vested (in dollars per share)	6.44
Forfeited (in dollars per share)	11.63
Unvested, December 31, 2021 (in dollars per share)	$ 8.37	$ 6.22

Equity-Based Compensation - Per

Equity-Based Compensation - Performance Share Unit Activity (Details) - Performance Share Units - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Number of Shares
Unvested, December 31, 2020 (in shares)	1,513,648
Granted (in shares)	886,091	1,020,161	607,130
Vested (in shares)	(292,241)
Forfeited/Canceled (in shares)	(192,909)
Unvested, December 31, 2021 (in shares)	1,914,589	1,513,648
Weighted Average
Unvested, December 31, 2020 (in dollars per share)	$ 12.36
Granted (in dollars per share)	12.04	$ 6.57	$ 15.58
Vested (in dollars per share)	17.48
Forfeited/Canceled (in dollars per share)	29.10
Unvested, December 31, 2021 (in dollars per share)	$ 9.77	$ 12.36

Commitments and Contingencies -

Commitments and Contingencies - Future Minimum Annual Commitments (Details) $ in Thousands	Dec. 31, 2021USD ($)
Minimum Purchase Commitments
2022	$ 15,065
2023	10,386
2024	5,397
2025	2,886
2026	2,180
Thereafter	9,288
Total future purchase commitments	$ 45,202

Commitments and Contingencies_2

Commitments and Contingencies - Narrative (Details)	May 17, 2017USD ($)	Dec. 31, 2021USD ($)claim	Dec. 31, 2020USD ($)claim	Dec. 31, 2019claim
Loss Contingencies
Purchased reserves	$ 94,400,000
Surety Bonds
Loss Contingencies
Surety bonds outstanding		$ 40,600,000
Reclamation Bonds
Loss Contingencies
Surety bonds outstanding		36,700,000
Other non-current assets
Loss Contingencies
Third party products claims liability under insurance in other long-term obligations		0	$ 0
Other long-term obligations
Loss Contingencies
Third party products claims liability under insurance in other long-term obligations		$ 900,000	$ 1,000,000
Pending Litigation
Loss Contingencies
Number of new claims filed | claim		2	1	1
Number of pending claims | claim		44

Pension and Post-Retirement B_3

Pension and Post-Retirement Benefits - Net Pension Benefit Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Pension Benefits
Pension Plans, Postretirement and Other Employee Benefits
Service cost	$ 2,855	$ 2,253	$ 1,304
Interest cost	2,619	4,037	5,375
Expected return on plan assets	(5,688)	(6,019)	(6,171)
Net amortization and deferral	3,212	3,127	1,648
Net pension benefit or post-retirement costs	2,998	3,398	2,156
Post-retirement Benefits
Pension Plans, Postretirement and Other Employee Benefits
Service cost	24	70	88
Interest cost	141	584	789
Unrecognized net (gain)/loss	(2,204)	0	(29)
Net pension benefit or post-retirement costs	$ (2,039)	$ 654	$ 848

Pension and Post-Retirement B_4

Pension and Post-Retirement Benefits - Changes in Benefit Obligations and Plan Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Plan Assets
Fair value of plan assets at January 1,	$ 120,563
Fair value of plan assets at December 31,	120,911	$ 120,563
Pension Benefits
Benefit Obligation
Benefit obligation at January 1,	157,198	148,491
Service cost	2,855	2,253	$ 1,304
Interest cost	2,619	4,037	5,375
Actuarial (gain) loss	(6,637)	11,119
Benefits paid	(9,551)	(8,649)
Other	(2,233)	(53)
Benefit obligation at December 31,	144,251	157,198	148,491
Plan Assets
Fair value of plan assets at January 1,	120,563	110,431
Actual return on plan assets	7,099	13,306
Employer contributions	2,800	5,475
Benefits paid	(9,551)	(8,649)
Other	0	0
Fair value of plan assets at December 31,	120,911	120,563	110,431
Plan assets less than benefit obligations at December 31 recognized as liability for pension and other post-retirement benefits	(23,340)	(36,635)
Post-retirement Benefits
Benefit Obligation
Benefit obligation at January 1,	11,318	22,054
Service cost	24	70	88
Interest cost	141	584	789
Actuarial (gain) loss	(3,193)	1,329
Benefits paid	(680)	(1,751)
Other	1,781	(10,968)
Benefit obligation at December 31,	9,391	11,318	22,054
Plan Assets
Fair value of plan assets at January 1,	0	0
Actual return on plan assets	0	0
Employer contributions	579	1,335
Benefits paid	(680)	(1,751)
Other	101	416
Fair value of plan assets at December 31,	0	0	$ 0
Plan assets less than benefit obligations at December 31 recognized as liability for pension and other post-retirement benefits	$ (9,391)	$ (11,318)

Pension and Post-Retirement B_5

Pension and Post-Retirement Benefits - Narrative (Details)	12 Months Ended
	Dec. 31, 2021USD ($)plan	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Pension Plans, Postretirement and Other Employee Benefits
Projected benefit obligation, nonqualified pension plan	$ 1,500,000	$ 1,600,000
Defined benefit plan, pension plans with accumulated benefit obligations in excess of plan assets, aggregate accumulated benefit obligation	1,500,000	1,600,000
Fair value of plan assets, nonqualified pension plan	0	0
Defined benefit plan, accumulated other comprehensive income net gains (losses), after tax	10,200,000	24,700,000
Total amounts in accumulated other comprehensive (loss) income	$ 7,800,000	$ 9,400,000
Number of multiemployer defined benefit plans | plan	3
Percentage of contributions to individual multiemployer funds	5.00%	5.00%	5.00%
Company contributions to defined contribution plan	$ 5,900,000	$ 4,400,000	$ 7,100,000
Certain Employees
Pension Plans, Postretirement and Other Employee Benefits
Company contribution over defined benefit plan	4.00%
All Eligible Employees
Pension Plans, Postretirement and Other Employee Benefits
Company contribution over defined benefit plan	6.00%
Pension Benefits
Pension Plans, Postretirement and Other Employee Benefits
Accumulated benefit obligation	$ 144,300,000	$ 157,200,000
Expected contributions to the plans for next fiscal year	0
Post-retirement Benefits
Pension Plans, Postretirement and Other Employee Benefits
Expected contributions to the plans for next fiscal year	$ 1,100,000

Pension and Post-Retirement B_6

Pension and Post-Retirement Benefits - Estimated Future Pension and Post-Retirement Benefit Payments (Details) $ in Thousands	Dec. 31, 2021USD ($)
Pension Benefits
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2022	$ 9,526
2023	9,446
2024	9,539
2025	9,367
2026	9,271
2027-2031	43,405
Post-retirement Benefits | Before Medicare Subsidy
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2022	1,104
2023	983
2024	911
2025	795
2026	742
2027-2031	2,775
Post-retirement Benefits | After Medicare Subsidy
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2022	1,104
2023	983
2024	911
2025	795
2026	742
2027-2031	$ 2,775

Pension and Post-Retirement B_7

Pension and Post-Retirement Benefits - Weighted-Average Assumptions Used (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Pension Benefits
Pension Plans, Postretirement and Other Employee Benefits
Discount rate	2.80%	2.50%
Long-term rate of return on plan assets	5.80%	6.30%
Pension Benefits | Minimum
Pension Plans, Postretirement and Other Employee Benefits
Long-term rate of compensation increase		3.00%
Post-retirement Benefits
Pension Plans, Postretirement and Other Employee Benefits
Discount rate	2.60%	2.10%
Post-retirement Benefits | Pre-65
Pension Plans, Postretirement and Other Employee Benefits
Initial rate	6.20%	6.50%
Ultimate rate	4.50%	4.50%
Post-retirement Benefits | Post-65
Pension Plans, Postretirement and Other Employee Benefits
Initial rate		7.00%
Ultimate rate		4.50%

Pension and Post-Retirement B_8

Pension and Post-Retirement Benefits - Investment Categories and Their Relative Percentage of Fair Value to Total Plan Assets (Details)	Dec. 31, 2021	Dec. 31, 2020
Pension Benefits | Equity securities
Pension Plans, Postretirement and Other Employee Benefits
Percentage of the fair value of the total plan assets	51.60%	57.90%
Pension Benefits | Debt securities
Pension Plans, Postretirement and Other Employee Benefits
Percentage of the fair value of the total plan assets	46.10%	41.30%
Pension Benefits | Cash
Pension Plans, Postretirement and Other Employee Benefits
Percentage of the fair value of the total plan assets	2.30%	0.80%
Post-retirement Benefits | Equity securities
Pension Plans, Postretirement and Other Employee Benefits
Percentage of the fair value of the total plan assets	0.00%	0.00%
Post-retirement Benefits | Debt securities
Pension Plans, Postretirement and Other Employee Benefits
Percentage of the fair value of the total plan assets	0.00%	0.00%
Post-retirement Benefits | Cash
Pension Plans, Postretirement and Other Employee Benefits
Percentage of the fair value of the total plan assets	0.00%	0.00%

Pension and Post-Retirement B_9

Pension and Post-Retirement Benefits - Fair Value of Pension Plan Assets, by Asset Category (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	$ 120,911	$ 120,563
Cash and cash equivalents
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	2,743	1,020
Diversified emerging markets
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	6,375	7,064
Foreign large blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	21,719	22,638
Large-cap blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	22,907	22,272
Mid-cap blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	11,411	12,972
Real Estate and Real Assets
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	4,822
Corporate notes and bonds
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	35,365	38,983
U.S. Treasuries
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	6,915	8,582
Mortgage-backed securities
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	2,242	1,780
Asset-backed securities
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	1,739	430
Real Assets
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	9,495
Level 1
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	104,692	117,333
Level 1 | Cash and cash equivalents
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 1 | Diversified emerging markets
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	6,375	7,064
Level 1 | Foreign large blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	21,719	22,638
Level 1 | Large-cap blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	22,907	22,272
Level 1 | Mid-cap blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	11,411	12,972
Level 1 | Real Estate and Real Assets
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	4,822
Level 1 | Corporate notes and bonds
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	35,365	38,983
Level 1 | U.S. Treasuries
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	6,915	8,582
Level 1 | Mortgage-backed securities
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 1 | Asset-backed securities
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 1 | Real Assets
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0
Level 2
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	16,219	3,230
Level 2 | Cash and cash equivalents
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	2,743	1,020
Level 2 | Diversified emerging markets
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 2 | Foreign large blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 2 | Large-cap blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 2 | Mid-cap blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 2 | Real Estate and Real Assets
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 2 | Corporate notes and bonds
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 2 | U.S. Treasuries
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 2 | Mortgage-backed securities
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	2,242	1,780
Level 2 | Asset-backed securities
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	1,739	430
Level 2 | Real Assets
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	9,495
Level 3
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets		0
Level 3 | Cash and cash equivalents
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 3 | Diversified emerging markets
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 3 | Foreign large blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 3 | Large-cap blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 3 | Mid-cap blend
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 3 | Real Estate and Real Assets
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 3 | Corporate notes and bonds
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 3 | U.S. Treasuries
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 3 | Mortgage-backed securities
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	0
Level 3 | Asset-backed securities
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	0	$ 0
Level 3 | Real Assets
Pension Plans, Postretirement and Other Employee Benefits
Fair value of pension plan assets	$ 0

Pension and Post-Retirement _10

Pension and Post-Retirement Benefits - Summary of Multiemployer Pension Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
LIUNA
Pension Plans, Postretirement and Other Employee Benefits
EIN/ Pension Plan No.	52-6074345/001
Company Contributions (in thousands)	$ 378	$ 361	$ 385
Expiration Date of CBA	Jun. 4, 2022
IUOE
Pension Plans, Postretirement and Other Employee Benefits
EIN/ Pension Plan No.	36-6052390/001
Company Contributions (in thousands)	$ 328	256	310
Expiration Date of CBA	Jul. 31, 2022
CSSS
Pension Plans, Postretirement and Other Employee Benefits
EIN/ Pension Plan No.	36-6044243/001
Company Contributions (in thousands)	$ 51	$ 51	$ 51
Central States, Southeast and Southwest Areas Pension Plan
Pension Plans, Postretirement and Other Employee Benefits
Withdrawal liability from pension plan	1,000
Withdrawal liability paid in monthly installments	$ 4

Leases - Narrative (Details)

Leases - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Gain on lease concessions	$ 0	$ 24,056	$ 0
COVID 19
Lessee, Lease, Description [Line Items]
Decrease to ROU due to lease concessions		1,000
Decrease to lease liabilities due to lease concessions		25,000
Gain on lease concessions		$ 24,000
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	Dec. 31, 2021	Dec. 31, 2020
Assets
Operating	$ 38,793	$ 37,130
Finance	3,448	339
Total leased assets	42,241	37,469
Current
Operating	14,469	17,388
Finance	1,061	55
Non-Current
Operating	75,130	76,361
Finance	2,485	295
Total lease liabilities	$ 93,145	$ 94,099
Weighted average remaining lease term:
Operating leases	6 years 10 months 24 days	6 years 10 months 24 days
Finance leases	3 years 7 months 6 days	2 years 10 months 24 days
Weighted average discount rate:
Operating leases	5.70%	5.80%
Finance leases	5.10%	5.00%
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Total leased assets	Total leased assets

Leases - Components of Lease Ex

Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Lessee, Lease, Description [Line Items]
Total lease costs	$ 35,065	$ 31,762
Finance lease expense	800	12
Cost of Sales
Lessee, Lease, Description [Line Items]
Operating lease costs	33,185	26,548
Short-term operating lease costs	17,900	9,600
Selling, general, and administrative
Lessee, Lease, Description [Line Items]
Operating lease costs	1,880	1,808
Short-term operating lease costs	400	400
Goodwill and other asset impairments
Lessee, Lease, Description [Line Items]
Operating lease costs	$ 0	$ 3,406

Leases - Supplemental Cash Flow

Leases - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows for operating leases	$ 24,451	$ 62,140	$ 75,352
Operating cash flows for finance leases	759	12
Right-of-use assets obtained in exchange for new lease liabilities:
Operating leases	17,350	10,747
Finance leases	$ 3,815	$ 359

Leases - Maturities of Lease Li

Leases - Maturities of Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Operating leases
2022	$ 20,128
2023	19,889
2024	16,441
2025	13,019
2026	11,116
Thereafter	30,642
Total lease payments	111,235
Less: Interest	17,939
Less: Other operating expenses	3,697
Total	89,599
Finance leases
2022	1,209
2023	1,199
2024	764
2025	605
2026	71
Thereafter	0
Total lease payments	3,848
Less: Interest	302
Less: Other operating expenses	0
Total	$ 3,546	$ 350

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
General business credits	$ 4,188	$ 4,188
Unrecognized tax benefits	856	0	$ 0	$ 0
Interest and penalties related to uncertain tax penalties	400	0	0
Unrecognized tax benefits, income tax penalties and interest accrued	400	0	$ 0
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	317,100
COVID 19
Operating Loss Carryforwards [Line Items]
Income tax refunds received		36,600
Refundable NOL credit under CARES Act	$ 21,500	26,300
Refunds received from NOL credits under CARES Act		4,900
Deferred tax benefit recorded under CARES Act		$ 22,300

Income Taxes - Income Before In

Income Taxes - Income Before Income Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
United States	$ (48,328)	$ (183,656)	$ (435,918)
Foreign	11,252	8,509	7,010
Total	$ (37,076)	$ (175,147)	$ (428,908)

Income Taxes - Income Tax Benef

Income Taxes - Income Tax Benefit (Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Current:
Federal	$ 0	$ 0	$ 0
State	(3,353)	(307)	(1,188)
Foreign	(1,385)	(1,473)	(1,343)
Current income tax (expense) benefit	(4,738)	(1,780)	(2,531)
Deferred:
Federal	7,589	57,214	90,457
State	(96)	4,591	11,225
Foreign	0	0	0
Deferred income tax (expense) benefit	7,493	61,805	101,682
Income tax benefit	$ 2,755	$ 60,025	$ 99,151

Income Taxes - Effective Income

Income Taxes - Effective Income Tax Rate on Pretax Earnings (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income tax benefit computed at U.S. federal statutory rate	$ 7,786	$ 36,781	$ 90,070
Decrease (increase) resulting from:
Statutory depletion	2,012	1,230	4,679
Prior year tax return reconciliation	(2,490)	(2,084)	3,121
State income taxes, net of federal benefit	445	5,013	9,486
Unrecognized tax benefits	(1,302)	0	0
Adjustment to deferred taxes from the CARES Act	0	22,318	0
Equity compensation	(627)	(1,477)	(6,440)
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Payment Arrangement, Executive, Amount	2,092	579	722
Other, net	(977)	(1,177)	(1,043)
Income tax benefit	$ 2,755	$ 60,025	$ 99,151

Income Taxes - Tax Effects on D

Income Taxes - Tax Effects on Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Gross deferred tax assets:
Net operating loss carry forward and state tax credits	$ 77,327	$ 90,087
Pension and post-retirement benefit costs	7,318	11,146
Property, plant and equipment	8,619	6,866
Accrued expenses	14,930	12,397
Inventories	1,200	121
Federal tax credits	4,188	4,188
Stock-based compensation expense	4,359	4,307
Interest expense limitation	16,921	14,127
Intangibles	7,876	11,304
Lease obligation liability	13,297	14,154
Other	4,399	5,286
Total deferred tax assets	160,434	173,983
Gross deferred tax liabilities:
Land and mineral property basis difference	(121,211)	(122,265)
Fixed assets and depreciation	(83,708)	(100,640)
Other	(289)	(464)
Total deferred tax liabilities	(205,208)	(223,369)
Net deferred tax liabilities	$ (44,774)	$ (49,386)

Income Taxes - Unrecognized Tax

Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance as of January 1	$ 0	$ 0	$ 0
Additions for tax positions of prior years	856	0	0
Balance as of December 31	$ 856	$ 0	$ 0

Revenue - Sales by Major Source

Revenue - Sales by Major Source (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Total Sales	$ 1,103,879	$ 845,885	$ 1,474,477
Oil & Gas Proppants
Disaggregation of Revenue [Line Items]
Total Sales	615,448	414,897
Industrial & Specialty Products
Disaggregation of Revenue [Line Items]
Total Sales	488,431	430,988
Product
Disaggregation of Revenue [Line Items]
Total Sales	896,203	732,187	1,168,472
Product | Oil & Gas Proppants
Disaggregation of Revenue [Line Items]
Total Sales	407,772	301,199
Product | Industrial & Specialty Products
Disaggregation of Revenue [Line Items]
Total Sales	488,431	430,988
Service
Disaggregation of Revenue [Line Items]
Total Sales	207,676	113,698	$ 306,005
Service | Oil & Gas Proppants
Disaggregation of Revenue [Line Items]
Total Sales	207,676	113,698
Service | Industrial & Specialty Products
Disaggregation of Revenue [Line Items]
Total Sales	$ 0	$ 0

Revenue - Changes in Contract A

Revenue - Changes in Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Unbilled Receivables
Beginning Balance	$ 47,982	$ 20,144
Reclassifications to billed receivables	(105,305)	(10,330)
Revenues recognized in excess of period billings	59,280	38,168
Ending Balance	1,957	47,982
Deferred Revenue
Beginning Balance	33,692	50,634
Revenues recognized from balances held at the beginning of the period	(13,172)	(19,704)
Revenues deferred from period collections on unfulfilled performance obligations	5,207	6,627
Revenues recognized from period collections	(4,986)	(3,865)
Ending Balance	$ 20,741	$ 33,692

Revenue - Narrative (Details)

Revenue - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Recognized revenue as variable consideration from shortfall penalties according to contract terms from shortfall penalties		$ 58,600	$ 48,000
Assets		2,219,600	2,246,947
Total sales		$ 1,103,879	845,885	$ 1,474,477
One Customer | Supply Commitment
Disaggregation of Revenue [Line Items]
Total sales	$ 49,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Disaggregation of Revenue [Line Items]
Remaining duration period of expected satisfaction of performance obligations		1 year
Foreign Operations
Disaggregation of Revenue [Line Items]
Assets			30,700	31,000
Total sales		$ 96,317	$ 86,179	$ 92,788
Minimum | Supply Agreement
Disaggregation of Revenue [Line Items]
Deferred revenue, average initial contract term		1 year
Maximum | Supply Agreement
Disaggregation of Revenue [Line Items]
Deferred revenue, average initial contract term		15 years

Revenue - Foreign Operations (D

Revenue - Foreign Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Total sales	$ 1,103,879	$ 845,885	$ 1,474,477
Pre-tax income	(37,076)	(175,147)	(428,908)
Net income	(33,761)	(114,094)	(329,082)
Foreign Operations
Disaggregation of Revenue [Line Items]
Total sales	96,317	86,179	92,788
Pre-tax income	11,252	8,509	7,010
Net income	$ 8,889	$ 6,722	$ 5,538

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Officer | Transportation Brokerage and Logistics Services Vendor
Related Party Transaction [Line Items]
Related party transactions	$ 0	$ 0	$ 0

Segment Reporting - Narrative (

Segment Reporting - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021USD ($)SegmentProduct	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Segment Reporting Information
Number of reportable segments | Segment	2
Number of product types | Product	600
Goodwill	$ 185,649	$ 185,649	$ 273,524
Oil & Gas Proppants
Segment Reporting Information
Goodwill	0	0	86,100
Industrial & Specialty Products
Segment Reporting Information
Goodwill	185,649	$ 185,649	$ 187,424
Operating Segments | Oil & Gas Proppants
Segment Reporting Information
Goodwill	0
Operating Segments | Industrial & Specialty Products
Segment Reporting Information
Goodwill	$ 185,600

Segment Reporting - Sales and S

Segment Reporting - Sales and Segment Contribution Margin for Reporting Segments and Other Operating Results (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information
Total sales	$ 1,103,879	$ 845,885	$ 1,474,477
Selling, general and administrative	(119,628)	(124,171)	(150,848)
Depreciation, depletion and amortization	(161,131)	(155,568)	(179,444)
Goodwill and other asset impairments	(202)	(110,688)	(363,847)
Interest expense	(71,157)	(79,885)	(95,472)
Other income, net, including interest income	6,146	24,350	19,519
Income tax benefit	2,755	60,025	99,151
Net loss	(34,321)	(115,122)	(329,757)
Less: Net loss attributable to non-controlling interest	(560)	(1,028)	(675)
Net loss attributable to U.S. Silica Holdings, Inc.	(33,761)	(114,094)	(329,082)
Operating Segments
Segment Reporting Information
Total sales	1,103,879	845,885	1,474,477
Total segment contribution margin	328,551	301,217	426,809
Segment Reconciling Items
Segment Reporting Information
Operating activities excluded from segment cost of sales	(19,655)	(30,402)	(85,625)
Selling, general and administrative	(119,628)	(124,171)	(150,848)
Depreciation, depletion and amortization	(161,131)	(155,568)	(179,444)
Goodwill and other asset impairments	(202)	(110,688)	(363,847)
Interest expense	(71,157)	(79,885)	(95,472)
Other income, net, including interest income	6,146	24,350	19,519
Oil & Gas Proppants
Segment Reporting Information
Total sales	615,448	414,897
Oil & Gas Proppants | Operating Segments
Segment Reporting Information
Total sales	615,448	414,897	1,010,521
Total segment contribution margin	160,052	142,041	248,594
Industrial & Specialty Products
Segment Reporting Information
Total sales	488,431	430,988
Industrial & Specialty Products | Operating Segments
Segment Reporting Information
Total sales	488,431	430,988	463,956
Total segment contribution margin	$ 168,499	$ 159,176	$ 178,215

Parent Company Financials - Con

Parent Company Financials - Condensed Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current Assets:
Cash and cash equivalents	$ 239,425	$ 150,920
Total current assets	575,915	486,313
Total assets	2,219,600	2,246,947
Current Liabilities:
Accounts payable and accrued expenses	167,670	121,920
Total current liabilities	205,871	194,895
Total liabilities	1,605,517	1,620,156
Stockholders’ Equity:
Preferred stock	0	0
Common stock	845	827
Additional paid-in capital	1,218,575	1,200,023
Retained deficit	(429,260)	(395,496)
Treasury stock, at cost	(186,294)	(181,615)
Accumulated other comprehensive income (loss)	349	(8,479)
Total U.S. Silica Holdings, Inc. stockholders’ equity	604,215	615,260
Non-controlling interest	9,868	11,531
Total stockholders' equity	614,083	626,791	$ 716,580	$ 1,052,304
Total liabilities and stockholders’ equity	2,219,600	2,246,947
Parent Company
Current Assets:
Cash and cash equivalents	46,996	46,851
Due from affiliates	165,632	168,276
Total current assets	212,628	215,127
Investment in subsidiaries	401,691	412,169
Total assets	614,319	627,296
Current Liabilities:
Accounts payable and accrued expenses	50	286
Dividends payable	186	219
Total current liabilities	236	505
Total liabilities	236	505
Stockholders’ Equity:
Preferred stock	0	0
Common stock	845	827
Additional paid-in capital	1,218,575	1,200,023
Retained deficit	(429,260)	(395,496)
Treasury stock, at cost	(186,294)	(181,615)
Accumulated other comprehensive income (loss)	349	(8,479)
Total U.S. Silica Holdings, Inc. stockholders’ equity	604,215	615,260
Non-controlling interest	9,868	11,531
Total stockholders' equity	614,083	626,791	$ 716,580	$ 1,052,304
Total liabilities and stockholders’ equity	$ 614,319	$ 627,296

Parent Company Financials - C_2

Parent Company Financials - Condensed Statements of Operations and Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Condensed Income Statements, Captions [Line Items]
Total sales	$ 1,103,879	$ 845,885	$ 1,474,477
Cost of sales	794,983	575,070	1,133,293
Operating expenses:
Selling, general and administrative	119,628	124,171	150,848
Total operating expenses	280,961	390,427	694,139
Operating income (loss)	27,935	(119,612)	(352,955)
Other income (expense)
Total other expense	(65,011)	(55,535)	(75,953)
Income tax benefit (expense)	2,755	60,025	99,151
Net loss	(34,321)	(115,122)	(329,757)
Less: Net loss attributable to non-controlling interest	(560)	(1,028)	(675)
Net loss attributable to U.S. Silica Holdings, Inc.	(33,761)	(114,094)	(329,082)
Other comprehensive (loss) income
Unrealized gain (loss) on derivatives (net of tax of $—, $973, and $(456) for 2021, 2020, and 2019, respectively)	0	3,053	(1,432)
Foreign currency translation adjustment (net of tax of $(309), $444, and $(60) for 2021, 2020 and 2019, respectively)	(1,000)	1,391	(188)
Pension and other post-retirement benefits liability adjustments (net of tax of $3,131, $2,207, and $(1,024) for 2021, 2020 and 2019, respectively)	9,828	6,931	(3,214)
Comprehensive loss	(25,493)	(103,747)	(334,591)
Less: Comprehensive loss attributable to non-controlling interest	(560)	(1,028)	(675)
Comprehensive loss attributable to U.S. Silica Holdings, Inc.	(24,933)	(102,719)	(333,916)
Tax expense (benefit) on unrealized gain (loss) on derivatives	0	973	(456)
Tax expense (benefit) on foreign currency translation adjustment	(309)	444	(60)
Tax (expense) benefit on pension and other post-retirement benefits liability adjustment	3,131	2,207	(1,024)
Parent Company
Condensed Income Statements, Captions [Line Items]
Total sales	0	0	0
Cost of sales	0	0	0
Operating expenses:
Selling, general and administrative	252	253	253
Total operating expenses	252	253	253
Operating income (loss)	(252)	(253)	(253)
Other income (expense)
Interest income	5	210	1,440
Total other expense	5	210	1,440
(Loss) income before income taxes and equity in net earnings of subsidiaries	(247)	(43)	1,187
Income tax benefit (expense)	0	0	(327)
(Loss) income before equity in net earnings of subsidiaries	(247)	(43)	860
Equity in earnings of subsidiaries, net of tax	(34,074)	(115,079)	(330,617)
Net loss	(34,321)	(115,122)	(329,757)
Less: Net loss attributable to non-controlling interest	(560)	(1,028)	(675)
Net loss attributable to U.S. Silica Holdings, Inc.	(33,761)	(114,094)	(329,082)
Other comprehensive (loss) income
Unrealized gain (loss) on derivatives (net of tax of $—, $973, and $(456) for 2021, 2020, and 2019, respectively)	0	3,053	(1,432)
Foreign currency translation adjustment (net of tax of $(309), $444, and $(60) for 2021, 2020 and 2019, respectively)	(1,000)	1,391	(188)
Pension and other post-retirement benefits liability adjustments (net of tax of $3,131, $2,207, and $(1,024) for 2021, 2020 and 2019, respectively)	9,828	6,931	(3,214)
Comprehensive loss	(25,493)	(103,747)	(334,591)
Less: Comprehensive loss attributable to non-controlling interest	(560)	(1,028)	(675)
Comprehensive loss attributable to U.S. Silica Holdings, Inc.	(24,933)	(102,719)	(333,916)
Tax expense (benefit) on unrealized gain (loss) on derivatives	0	973	(456)
Tax expense (benefit) on foreign currency translation adjustment	(309)	444	(60)
Tax (expense) benefit on pension and other post-retirement benefits liability adjustment	$ 3,131	$ 2,207	$ (1,024)

Parent Company Financials - C_3

Parent Company Financials - Condensed Statements of Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance	$ 626,791	$ 716,580	$ 1,052,304
Net loss	(34,321)	(115,122)	(329,757)
Unrealized gain (loss) on derivatives	0	3,053	(1,432)
Foreign currency translation adjustment	(1,000)	1,391	(188)
Pension and post-retirement liability	9,828	6,931	(3,214)
Cash dividend declared	(3)	(1,446)	(18,728)
Contributions from non-controlling interest		1,196	4,554
Distributions to non-controlling interest	1,103
Equity-based compensation	18,809	14,911	15,906
Proceeds from options exercised	105		128
Shares withheld for tax payments related to vested restricted stock and stock units	(5,023)	(703)	(2,993)
Ending Balance	$ 614,083	$ 626,791	$ 716,580
Dividends declared per share (in dollars per share)	$ 0	$ 0.02	$ 0.25
Total U.S. Silica Holdings Inc., Stockholders’ Equity
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance	$ 615,260	$ 705,217	$ 1,044,820
Net loss	(33,761)	(114,094)	(329,082)
Unrealized gain (loss) on derivatives		3,053	(1,432)
Foreign currency translation adjustment	(1,000)	1,391	(188)
Pension and post-retirement liability	9,828	6,931	(3,214)
Cash dividend declared	(3)	(1,446)	(18,728)
Equity-based compensation	18,809	14,911	15,906
Proceeds from options exercised	105		128
Shares withheld for tax payments related to vested restricted stock and stock units	(5,023)	(703)	(2,993)
Ending Balance	604,215	615,260	705,217
Common Stock
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance	827	823	818
Shares withheld for tax payments related to vested restricted stock and stock units	18	4	5
Ending Balance	845	827	823
Treasury Stock
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance	(181,615)	(180,912)	(178,215)
Proceeds from options exercised	344		296
Shares withheld for tax payments related to vested restricted stock and stock units	(5,023)	(703)	(2,993)
Ending Balance	(186,294)	(181,615)	(180,912)
Additional Paid-In Capital
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance	1,200,023	1,185,116	1,169,383
Equity-based compensation	18,809	14,911	15,906
Proceeds from options exercised	(239)		(168)
Shares withheld for tax payments related to vested restricted stock and stock units	(18)	(4)	(5)
Ending Balance	1,218,575	1,200,023	1,185,116
Retained Earnings (Deficit) - Present
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance	(395,496)	(279,956)	67,854
Net loss	(33,761)	(114,094)	(329,082)
Cash dividend declared	(3)	(1,446)	(18,728)
Ending Balance	(429,260)	(395,496)	(279,956)
Accumulated Other Comprehensive (Loss) Income
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance	(8,479)	(19,854)	(15,020)
Unrealized gain (loss) on derivatives		3,053	(1,432)
Foreign currency translation adjustment	(1,000)	1,391	(188)
Pension and post-retirement liability	9,828	6,931	(3,214)
Ending Balance	349	(8,479)	(19,854)
Non-controlling Interest
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance	11,531	11,363	7,484
Net loss	(560)	(1,028)	(675)
Contributions from non-controlling interest		1,196	4,554
Distributions to non-controlling interest	1,103
Ending Balance	9,868	11,531	11,363
Parent Company
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance	626,791	716,580	1,052,304
Net loss	(34,321)	(115,122)	(329,757)
Unrealized gain (loss) on derivatives	0	3,053	(1,432)
Foreign currency translation adjustment	(1,000)	1,391	(188)
Pension and post-retirement liability	9,828	6,931	(3,214)
Cash dividend declared	(3)	(1,446)	(18,728)
Contributions from non-controlling interest		1,196
Distributions to non-controlling interest	(1,103)
Equity-based compensation	18,809	14,911	15,906
Proceeds from options exercised	105		128
Shares withheld for tax payments related to vested restricted stock and stock units	(5,023)	(703)	(2,993)
Ending Balance	614,083	$ 626,791	$ 716,580
Dividends declared per share (in dollars per share)		$ 0.02	$ 0.25
Parent Company | Total U.S. Silica Holdings Inc., Stockholders’ Equity
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance	615,260	$ 705,217	$ 1,044,820
Net loss	(33,761)	(114,094)	(329,082)
Unrealized gain (loss) on derivatives		3,053	(1,432)
Foreign currency translation adjustment	(1,000)	1,391	(188)
Pension and post-retirement liability	9,828	6,931	(3,214)
Cash dividend declared	(3)	(1,446)	(18,728)
Equity-based compensation	18,809	14,911	15,906
Proceeds from options exercised	105		128
Shares withheld for tax payments related to vested restricted stock and stock units	(5,023)	(703)	(2,993)
Ending Balance	604,215	615,260	705,217
Parent Company | Common Stock
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance	827	823	818
Shares withheld for tax payments related to vested restricted stock and stock units	18	4	5
Ending Balance	845	827	823
Parent Company | Treasury Stock
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance	(181,615)	(180,912)	(178,215)
Proceeds from options exercised	344		296
Shares withheld for tax payments related to vested restricted stock and stock units	(5,023)	(703)	(2,993)
Ending Balance	(186,294)	(181,615)	(180,912)
Parent Company | Additional Paid-In Capital
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance	1,200,023	1,185,116	1,169,383
Equity-based compensation	18,809	14,911	15,906
Proceeds from options exercised	(239)		(168)
Shares withheld for tax payments related to vested restricted stock and stock units	(18)	(4)	(5)
Ending Balance	1,218,575	1,200,023	1,185,116
Parent Company | Retained Earnings (Deficit) - Present
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance	(395,496)	(279,956)	67,854
Net loss	(33,761)	(114,094)	(329,082)
Cash dividend declared	(3)	(1,446)	(18,728)
Ending Balance	(429,260)	(395,496)	(279,956)
Parent Company | Accumulated Other Comprehensive (Loss) Income
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance	(8,479)	(19,854)	(15,020)
Unrealized gain (loss) on derivatives		3,053	(1,432)
Foreign currency translation adjustment	(1,000)	1,391	(188)
Pension and post-retirement liability	9,828	6,931	(3,214)
Ending Balance	349	(8,479)	(19,854)
Parent Company | Non-controlling Interest
Condensed Stockholders' Equity Statement [Line Items]
Beginning Balance	11,531	11,363	7,484
Net loss	(560)	(1,028)	(675)
Contributions from non-controlling interest		1,196
Distributions to non-controlling interest	(1,103)
Ending Balance	$ 9,868	$ 11,531	$ 11,363

Parent Company Financials - C_4

Parent Company Financials - Condensed Statements of Cash Flows (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Condensed Cash Flow Statements, Captions [Line Items]
Net loss	$ (34,321,000)	$ (115,122,000)	$ (329,757,000)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Accounts payable and accrued expenses	48,709,000	(86,734,000)	21,024,000
Net cash provided by (used in) operating activities	169,347,000	(3,403,000)	147,809,000
Investing activities:
Net cash used in investing activities	(29,856,000)	(27,564,000)	(120,393,000)
Financing activities:
Dividends paid	(26,000)	(6,185,000)	(18,592,000)
Proceeds from options exercised	105,000	0	128,000
Tax payments related to shares withheld for vested restricted stock and stock units	(5,023,000)	(703,000)	(2,993,000)
Net cash used in financing activities	(50,986,000)	(3,853,000)	(44,174,000)
Cash and cash equivalents, beginning of period	150,920,000	185,740,000	202,498,000
Cash and cash equivalents, end of period	239,425,000	150,920,000	185,740,000
Cash received during the period for:
Interest	(64,650,000)	(73,695,000)	(87,286,000)
Cash dividends paid to the parent by its consolidated entities	0	0	0
Parent Company
Condensed Cash Flow Statements, Captions [Line Items]
Net loss	(34,321,000)	(115,122,000)	(329,757,000)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Undistributed loss from equity method investment, net	34,074,000	115,079,000	330,617,000
Accounts payable and accrued expenses	(236,000)	155,000	(88,000)
Net cash provided by (used in) operating activities	(483,000)	112,000	772,000
Investing activities:
Investment in subsidiary	0	0	0
Net cash used in investing activities	0	0	0
Financing activities:
Dividends paid	(26,000)	(6,185,000)	(18,592,000)
Proceeds from options exercised	105,000	0	128,000
Tax payments related to shares withheld for vested restricted stock and stock units	(5,023,000)	(703,000)	(2,993,000)
(Distributions to) contributions from non-controlling interest	(1,103,000)	1,196,000	4,554,000
Net financing activities with subsidiaries	6,675,000	582,000	(39,171,000)
Net cash used in financing activities	628,000	(5,110,000)	(56,074,000)
Net increase (decrease) in cash and cash equivalents	145,000	(4,998,000)	(55,302,000)
Cash and cash equivalents, beginning of period	46,851,000	51,849,000	107,151,000
Cash and cash equivalents, end of period	46,996,000	46,851,000	51,849,000
Cash received during the period for:
Interest	$ (17,000)	$ (210,000)	$ (1,440,000)

Impairments - Schedule of Impai

Impairments - Schedule of Impairment Charges (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disclosure Text Block Supplement [Abstract]
Inventories, net	$ 0	$ 6,837	$ 4,100
Property, plant and mine development, net	164	11,822	243,064
Operating lease right-of-use assets	0	3,406	115,443
Goodwill	0	86,100	0
Intangible assets, net	38	2,523	1,240
Total	$ 202	$ 110,688	$ 363,847

Impairments - Narrative (Detail

Impairments - Narrative (Details) - Industrial & Specialty Products - Goodwill And Other Assets Impairments $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)
Technology and intellectual property
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of finite-lived intangibles	$ 1.4
Trade names
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of indefinite-lived intangibles	$ 1.1

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ in Thousands	Feb. 25, 2022	Jan. 31, 2022	Dec. 31, 2021
Subsequent Event
Purchase obligation			$ 45,202
Subsequent Event
Subsequent Event
One time payment	$ 6,500
Subsequent Event | Forecast
Subsequent Event
Purchase obligation		$ 9,900