U.S. Silica (SLCA) 10-Q 29 Apr 22 2022 Q1 Quarterly report Financial data

Cover

Cover - shares	3 Months Ended
	Mar. 31, 2022	Apr. 22, 2022
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2022
Document Transition Report	false
Entity File Number	001-35416
Entity Registrant Name	U.S. Silica Holdings, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	26-3718801
Entity Address, Address Line One	24275 Katy Freeway, Suite 600
Entity Address, City or Town	Katy
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77494
City Area Code	281
Local Phone Number	258-2170
Title of 12(b) Security	Common Stock, $0.01 par value
Trading Symbol	SLCA
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		75,477,339
Amendment Flag	false
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q1
Entity Central Index Key	0001524741
Current Fiscal Year End Date	--12-31

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current Assets:
Cash and cash equivalents	$ 239,768	$ 239,425
Accounts receivable, net	198,835	202,759
Inventories, net	123,784	115,713
Prepaid expenses and other current assets	14,525	18,018
Total current assets	576,912	575,915
Property, plant and mine development, net	1,228,071	1,258,646
Lease right-of-use assets	41,751	42,241
Goodwill	185,649	185,649
Intangible assets, net	147,694	150,054
Other assets	7,620	7,095
Total assets	2,187,697	2,219,600
Current Liabilities:
Accounts payable and accrued expenses	162,970	167,670
Current portion of operating lease liabilities	13,158	14,469
Current portion of long-term debt	16,303	18,285
Current portion of deferred revenue	2,643	4,247
Income tax payable	8,866	1,200
Total current liabilities	203,940	205,871
Long-term debt, net	1,191,980	1,193,135
Deferred revenue	16,491	16,494
Liability for pension and other post-retirement benefits	28,843	32,935
Deferred income taxes, net	30,388	44,774
Operating lease liabilities	71,355	75,130
Other long-term liabilities	33,906	37,178
Total liabilities	1,576,903	1,605,517
Commitments and Contingencies (Note M)
Stockholders’ Equity:
Preferred stock, $0.01 par value, 10,000,000 shares authorized; zero issued and outstanding at March 31, 2022 and December 31, 2021	0	0
Common stock, $0.01 par value, 500,000,000 shares authorized; 85,341,383 issued and 75,434,553 outstanding at March 31, 2022; 84,746,194 issued and 75,033,352 outstanding at December 31, 2021	851	845
Additional paid-in capital	1,222,780	1,218,575
Retained deficit	(437,641)	(429,260)
Treasury stock, at cost, 9,906,830 and 9,712,842 shares at March 31, 2022 and December 31, 2021, respectively	(188,092)	(186,294)
Accumulated other comprehensive income	3,502	349
Total U.S. Silica Holdings, Inc. stockholders’ equity	601,400	604,215
Non-controlling interest	9,394	9,868
Total stockholders' equity	610,794	614,083
Total liabilities and stockholders’ equity	$ 2,187,697	$ 2,219,600

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock authorized (in shares)	10,000,000	10,000,000
Preferred stock issued (in shares)	0	0
Preferred stock outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock authorized (in shares)	500,000,000	500,000,000
Common stock issued (in shares)	85,341,383	84,746,194
Common stock outstanding (in shares)	75,434,553	75,033,352
Treasury stock, at cost (in shares)	9,906,830	9,712,842

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Sales:
Total sales	$ 304,887	$ 234,416
Cost of sales (excluding depreciation, depletion and amortization):
Total cost of sales (excluding depreciation, depletion and amortization)	226,869	176,989
Operating expenses:
Selling, general and administrative	40,110	26,224
Depreciation, depletion and amortization	37,749	41,348
Goodwill and other asset impairments	0	38
Total operating expenses	77,859	67,610
Operating income (loss)	159	(10,183)
Other (expense) income:
Interest expense	(17,173)	(17,711)
Other income, net, including interest income	1,531	2,605
Total other expense	(15,642)	(15,106)
Loss before income taxes	(15,483)	(25,289)
Income tax benefit	6,969	4,354
Net loss	(8,514)	(20,935)
Less: Net loss attributable to non-controlling interest	(121)	(157)
Net loss attributable to U.S. Silica Holdings, Inc.	$ (8,393)	$ (20,778)
Loss per share attributable to U.S. Silica Holdings, Inc.:
Basic (in dollars per share)	$ (0.11)	$ (0.28)
Diluted (in dollars per share)	$ (0.11)	$ (0.28)
Weighted average shares outstanding:
Basic (in shares)	75,240	73,927
Diluted (in shares)	75,240	73,927
Dividends declared per share (in dollars per share)	$ 0	$ 0
Product
Sales:
Total sales	$ 233,234	$ 191,390
Cost of sales (excluding depreciation, depletion and amortization):
Total cost of sales (excluding depreciation, depletion and amortization)	173,608	142,797
Service
Sales:
Total sales	71,653	43,026
Cost of sales (excluding depreciation, depletion and amortization):
Total cost of sales (excluding depreciation, depletion and amortization)	$ 53,261	$ 34,192

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Statement of Comprehensive Income [Abstract]
Net loss	$ (8,514)	$ (20,935)
Other comprehensive income (loss):
Foreign currency translation adjustment (net of tax of $(98) and $(180)) for the three months ended March 31, 2022 and 2021, respectively.	(309)	(569)
Pension and other post-retirement benefits liability adjustment (net of tax of $1,084 and $3,234) for the three months ended March 31, 2022 and 2021, respectively.	3,462	10,151
Comprehensive loss	(5,361)	(11,353)
Less: Comprehensive loss attributable to non-controlling interest	(121)	(157)
Comprehensive loss attributable to U.S. Silica Holdings, Inc.	$ (5,240)	$ (11,196)

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Statement of Comprehensive Income [Abstract]
Tax expense (benefit) on foreign currency translation adjustment	$ (98)	$ (180)
Tax (expense) benefit on pension and other post-retirement benefits liability adjustment	$ 1,084	$ 3,234

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Total U.S. Silica Holdings Inc., Stockholders’ Equity	Common Stock	Treasury Stock	Additional Paid-In Capital	Retained Deficit	Accumulated Other Comprehensive Income (Loss)	Non-controlling Interest
Beginning 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	(20,935)	(20,778)				(20,778)		(157)
Foreign currency translation adjustment	(569)	(569)					(569)
Pension and post-retirement liability	10,151	10,151					10,151
Cash dividend (declared)	7	7				7
Distributions to non-controlling interest	(174)							(174)
Common stock-based compensation plans activity:
Equity-based compensation	4,143	4,143			4,143
Proceeds from options exercised	105	105		344	(239)
Tax payments related to shares withheld for vested restricted stock and stock units	(1,244)	(1,244)	5	(1,244)	(5)
Ending Balance at Mar. 31, 2021	618,275	607,075	832	(182,515)	1,203,922	(416,267)	1,103	11,200
Beginning Balance at Dec. 31, 2021	614,083	604,215	845	(186,294)	1,218,575	(429,260)	349	9,868
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(8,514)	(8,393)				(8,393)		(121)
Foreign currency translation adjustment	(309)	(309)					(309)
Pension and post-retirement liability	3,462	3,462					3,462
Cash dividend (declared)	12	12				12
Distributions to non-controlling interest	(353)							(353)
Common stock-based compensation plans activity:
Equity-based compensation	4,382	4,382			4,382
Proceeds from options exercised	83	83		254	(171)
Tax payments related to shares withheld for vested restricted stock and stock units	(2,052)	(2,052)	6	(2,052)	(6)
Ending Balance at Mar. 31, 2022	$ 610,794	$ 601,400	$ 851	$ (188,092)	$ 1,222,780	$ (437,641)	$ 3,502	$ 9,394

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating activities:
Net loss	$ (8,514)	$ (20,935)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation, depletion and amortization	37,749	41,348
Goodwill and other asset impairments	0	38
Debt issuance amortization	1,253	1,271
Original issue discount amortization	255	258
Deferred income taxes	(15,312)	(4,869)
Deferred revenue	(873)	(5,132)
Gain on disposal of property, plant and equipment	(375)	(35)
Equity-based compensation	4,382	4,143
Allowance for credit losses, net of recoveries	286	10
Other	8,329	18,456
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable	4,088	(4,917)
Inventories	(7,882)	(1,467)
Prepaid expenses and other current assets	3,493	(568)
Income taxes	7,666	218
Accounts payable and accrued expenses	(5,197)	9,053
Operating lease liabilities	(7,518)	(8,159)
Liability for pension and other post-retirement benefits	(4,740)	(13,602)
Other noncurrent assets and liabilities	(2,011)	(1,469)
Net cash provided by operating activities	15,079	13,642
Investing activities:
Capital expenditures	(7,030)	(3,511)
Capitalized intellectual property costs	(67)	(95)
Proceeds from sale of property, plant and equipment	714	72
Net cash used in investing activities	(6,383)	(3,534)
Financing activities:
Dividends paid	(151)	0
Proceeds from options exercised	83	105
Tax payments related to shares withheld for vested restricted stock and stock units	(2,052)	(1,244)
Payments on short-term debt	(2,212)	(2,077)
Payments on long-term debt	(3,338)	(3,200)
Distributions to non-controlling interest	(353)	(174)
Principal payments on finance lease obligations	(330)	(27)
Net cash used in financing activities	(8,353)	(6,617)
Net increase in cash and cash equivalents	343	3,491
Cash and cash equivalents, beginning of period	239,425	150,920
Cash and cash equivalents, end of period	239,768	154,411
Cash paid (received) during the period for:
Interest	15,702	16,104
Taxes, net of refunds	(20,403)	(15,889)
Non-cash items:
Accrued capital expenditures	121	792
Net assets assumed in business acquisition	$ 0	$ 68

Organization and Basis of Prese

Organization and Basis of Presentation	3 Months Ended
	Mar. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
ORGANIZATION AND BASIS OF PRESENTATION	NOTE A—ORGANIZATION AND BASIS OF PRESENTATION Organization U.S. Silica Holdings, Inc. (“Holdings,” and together with its subsidiaries “we,” “us” or the “Company”) is a global performance materials company and a leading producer of commercial silica used in the oil and gas industry and in a wide range of industrial applications. In addition, through our subsidiary EP Minerals, LLC ("EPM"), we are an industry leader in the production of industrial minerals, including diatomaceous earth, clay (calcium bentonite and calcium montmorillonite) and perlite. During our 122-year history, we have developed core competencies in mining, processing, logistics and materials science that enable us to produce and cost-effectively deliver products to customers across our end markets. Our operations are organized into two reportable segments based on end markets served: (1) Oil & Gas Proppants and (2) Industrial & Specialty Products. See Note S - Segment Reporting for more information on our reportable segments. Basis of Presentation and Consolidation The accompanying unaudited Condensed Consolidated Financial Statements for the quarter ended March 31, 2022 included in this Quarterly Report on Form 10-Q have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X issued by the U.S. Securities and Exchange Commission (“SEC”). They do not contain certain information included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2021; therefore, the unaudited Condensed Consolidated Financial Statements should be read in conjunction with that Annual Report on Form 10-K. Operating results for the three-month period ended March 31, 2022 are not necessarily indicative of the results that may be expected for the full year ending December 31, 2022. In the opinion of management, all adjustments necessary for a fair presentation have been included. Such adjustments are of a normal, recurring nature. The unaudited Condensed Consolidated Financial Statements include the accounts of Holdings and its direct and indirect wholly-owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. Throughout this report we refer to (i) our unaudited Condensed Consolidated Balance Sheets as our “Balance Sheets,” (ii) our unaudited Condensed Consolidated Statements of Operations as our “Income Statements,” and (iii) our unaudited Condensed Consolidated Statements of Cash Flows as our “Cash Flows.”

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	NOTE B—SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Use of Estimates and Assumptions The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the related disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. The 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. New Accounting Pronouncements Recently Adopted None. New Accounting Pronouncements Not Yet Adopted In March 2020, the FASB issued Accounting Standards Update ("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 March 31, 2022, 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 I - Debt for discussion of the use of the adjusted LIBOR rate in connection with borrowings under our senior secured revolving credit facility.

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2022
Earnings Per Share [Abstract]
EARNINGS PER SHARE	NOTE C—EARNINGS PER SHARE Basic earnings per common share is computed by dividing income available to common stockholders by the weighted average number of common shares outstanding for the period. Diluted earnings per common share is computed similarly to basic earnings per common share except that the weighted average number of common shares outstanding is increased to include the number of additional common shares that would have been outstanding if the potentially dilutive common shares had been issued. Diluted net earnings per share assumes the conversion of contingently convertible securities and stock options under the treasury stock method, if dilutive. Contingently convertible securities and stock options are excluded from the calculation of fully diluted earnings per share if they are anti-dilutive, including when we incur a loss from continuing operations. The following table shows the computation of basic and diluted earnings per share: In thousands, except per share amounts Three Months Ended 2022 2021 Numerator: Net loss attributable to U.S. Silica Holdings, Inc. $ (8,393) $ (20,778) Denominator: Weighted average shares outstanding 75,240 73,927 Diluted effect of stock awards — — Weighted average shares outstanding assuming dilution 75,240 73,927 Loss per share attributable to U.S. Silica Holdings, Inc.: Basic loss per share $ (0.11) $ (0.28) Diluted loss per share $ (0.11) $ (0.28) Potentially dilutive shares were excluded from the calculation of diluted weighted average shares outstanding and diluted earnings per share because we were in a net loss position. Certain stock options, restricted stock awards and performance share units were excluded from the computation of diluted earnings per share because their effect would have been anti-dilutive. Such potentially dilutive shares and stock awards excluded from the calculation of diluted earnings per common share were as follows: In thousands Three Months Ended 2022 2021 Potentially dilutive shares excluded 1,808 1,852 Stock options excluded 541 608 Restricted stock and performance share unit awards excluded 12 50

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	3 Months Ended
	Mar. 31, 2022
Equity [Abstract]
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	NOTE D—ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) Accumulated other comprehensive income (loss) consists of fair value adjustments associated with accumulated adjustments for net experience losses and prior service costs related to employee benefit plans and foreign currency translation adjustments, net of tax. The following table presents the changes in accumulated other comprehensive income (loss) by component (in thousands): For the Three Months Ended March 31, 2022 Foreign currency translation adjustments Pension and other post-retirement benefits liability Total Beginning Balance $ (417) $ 766 $ 349 Other comprehensive (loss) gain before reclassifications (309) 3,494 3,185 Amounts reclassified from accumulated other comprehensive income — (32) (32) Ending Balance $ (726) $ 4,228 $ 3,502 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.

Accounts Receivable

Accounts Receivable	3 Months Ended
	Mar. 31, 2022
Receivables [Abstract]
ACCOUNTS RECEIVABLE	NOTE E—ACCOUNTS RECEIVABLE Accounts receivable are recorded when billed or accrued and represent claims against third parties that will be settled in cash. The carrying value of our accounts receivable, net of the allowance for credit losses, represents their estimated net realizable value. Accounts receivable (in thousands) consisted of the following: March 31, December 31, Trade receivables $ 201,081 $ 182,992 Less: Allowance for credit losses (5,511) (5,248) Net trade receivables 195,570 177,744 Other receivables (1) 3,265 25,015 Total accounts receivable $ 198,835 $ 202,759 (1) Other receivables included $0.4 million and $21.5 million at March 31, 2022 and December 31, 2021, respectively, 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): Oil & Gas Proppants Industrial & Specialty Products Total Beginning balance, December 31, 2021 $ 4,625 $ 623 $ 5,248 Allowance for credit losses — 286 286 Write-offs — (23) (23) Ending balance, March 31, 2022 $ 4,625 $ 886 $ 5,511

Inventories

Inventories	3 Months Ended
	Mar. 31, 2022
Inventory Disclosure [Abstract]
INVENTORIES	NOTE F—INVENTORIES Inventories (in thousands) consisted of the following: March 31, 2022 December 31, 2021 Supplies $ 49,224 $ 45,605 Raw materials and work in process 36,542 36,529 Finished goods 38,018 33,579 Total inventories $ 123,784 $ 115,713

Property, Plant and Mine Develo

Property, Plant and Mine Development	3 Months Ended
	Mar. 31, 2022
Property, Plant and Equipment [Abstract]
PROPERTY, PLANT AND MINE DEVELOPMENT	NOTE G—PROPERTY, PLANT AND MINE DEVELOPMENT Property, plant and mine development (in thousands) consisted of the following: March 31, December 31, Mining property and mine development $ 788,441 $ 789,122 Asset retirement cost 19,937 22,283 Land 55,551 55,541 Land improvements 76,248 76,248 Buildings 72,252 72,207 Machinery and equipment 1,193,025 1,189,548 Furniture and fixtures 3,932 3,932 Construction-in-progress 36,264 35,060 2,245,650 2,243,941 Accumulated depreciation, depletion, amortization and impairment charges (1,017,579) (985,295) Total property, plant and mine development, net $ 1,228,071 $ 1,258,646 Depreciation, depletion, and amortization expense related to property, plant and mine development was $34.8 million and $38.6 million for the three months ended March 31, 2022 and 2021, respectively.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	3 Months Ended
	Mar. 31, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND INTANGIBLE ASSETS	NOTE H—GOODWILL AND INTANGIBLE ASSETS The changes in the carrying amount of goodwill (in thousands) by business segment consisted of the following: Oil & Gas Proppants Segment Industrial & Specialty Products Segment Totals Balance at December 31, 2021 $ — $ 185,649 $ 185,649 Impairment loss — — — Balance at March 31, 2022 $ — $ 185,649 $ 185,649 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. There were no triggering events during the first three months of 2022, therefore, no impairment charges were recorded related to goodwill or trade names for the three months ended March 31, 2022. The changes in the carrying amount of intangible assets (in thousands) consisted of the following: March 31, 2022 December 31, 2021 Gross Carrying Amount Accumulated Amortization Impairments Net Gross Carrying Amount Accumulated Amortization Impairments Net Technology and intellectual property $ 71,270 $ (26,329) $ — $ 44,941 $ 71,209 $ (25,069) $ (38) $ 46,102 Customer relationships 66,999 (29,186) — 37,813 66,999 (27,987) — 39,012 Total definite-lived intangible assets: $ 138,269 $ (55,515) $ — $ 82,754 $ 138,208 $ (53,056) $ (38) $ 85,114 Trade names 64,240 — — 64,240 64,240 — — 64,240 Other 700 — — 700 700 — — 700 Total intangible assets: $ 203,209 $ (55,515) $ — $ 147,694 $ 203,148 $ (53,056) $ (38) $ 150,054 Estimated useful life of technology and intellectual property is 15 years. Estimated useful life of customer relationships is a range of 13 - 20 years. Amortization expense was $2.4 million for both the three months ended March 31, 2022 and 2021, respectively. The estimated amortization expense related to definite-lived intangible assets (in thousands) for the five succeeding years is as follows: 2022 (remaining nine months) $ 7,249 2023 $ 9,665 2024 $ 9,665 2025 $ 9,665 2026 $ 9,665

Debt

Debt	3 Months Ended
	Mar. 31, 2022
Debt Disclosure [Abstract]
DEBT	NOTE I—DEBT Debt (in thousands) consisted of the following: March 31, December 31, Senior secured credit facility: Revolver expiring May 1, 2023 (4.50% at March 31, 2022 and 4.13% at December 31, 2021) $ — $ — Term Loan—final maturity May 1, 2025 (5.00% at March 31, 2022 and 5.00% at December 31, 2021) 1,218,662 1,222,000 Less: Unamortized original issue discount (3,095) (3,350) Less: Unamortized debt issuance cost (13,947) (15,200) Insurance financing notes payable 2,212 4,424 Finance leases (See Note O - Leases) 4,451 3,546 Total debt 1,208,283 1,211,420 Less: current portion (16,303) (18,285) Total long-term portion of debt $ 1,191,980 $ 1,193,135 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 our domestic subsidiaries' assets and a pledge of the equity interests in such entities. The Term Loan matures on May 1, 2025, and the Revolver expires May 1, 2023. We capitalized $38.7 million in debt issuance costs and original issue discount as a result of the Credit Agreement. The Credit Facility contains covenants that, among other things, limit our ability, and certain of our subsidiaries' abilities, to create, incur or assume indebtedness and liens, to make acquisitions or investments, to sell assets and to pay dividends. The Credit Agreement also requires us to maintain a consolidated leverage ratio of no more than 3.75:1.00 as of the last day of any fiscal quarter whenever usage of the Revolver (other than certain undrawn letters of credit) exceeds 30% of the Revolver commitment. These covenants are subject to a number of important exceptions and qualifications. The Credit Agreement includes events of default and other affirmative and negative covenants that are usual for facilities and transactions of this type. As of March 31, 2022 and December 31, 2021, we are in compliance with all covenants in accordance with our senior secured Credit Facility. Term Loan At March 31, 2022, contractual maturities of our Term Loan (in thousands) are as follows: 2022 (remaining nine months) $ 9,600 2023 12,800 2024 12,800 2025 1,183,462 2026 — Thereafter — Total $ 1,218,662 Revolving Line-of-Credit We have a $100.0 million Revolver with zero drawn and $21.6 million allocated for letters of credit as of March 31, 2022, leaving $78.4 million available under the Revolver. Based on our consolidated leverage ratio of 5.07:1.00 as of March 31, 2022, we may draw up to approximately $30.0 million without the consent of our lenders. With the consent of our lenders, we have access to the full availability of the Revolver. 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 March 31, 2022, the notes payable had a balance of $2.2 million.

Asset Retirement Obligations

Asset Retirement Obligations	3 Months Ended
	Mar. 31, 2022
Asset Retirement Obligation Disclosure [Abstract]
ASSET RETIREMENT OBLIGATIONS	NOTE J—ASSET RETIREMENT OBLIGATIONS Mine reclamation or future remediation costs for inactive mines are accrued based on management’s best estimate at the end of each period of the costs expected to be incurred at such site. Such cost estimates include, where applicable, ongoing care, maintenance and monitoring costs. Changes in estimates at inactive mines are reflected in earnings in the period an estimate is revised. Liabilities related to our asset retirement obligations are reflected in other long-term liabilities on our balance sheets. Changes in the asset retirement obligations (in thousands) are as follows: Three Months Ended 2022 2021 Beginning balance $ 32,049 $ 24,717 Accretion 374 342 Additions and revisions of estimates (3,126) 279 Ending balance $ 29,297 $ 25,338

Fair Value Accounting

Fair Value Accounting	3 Months Ended
	Mar. 31, 2022
Fair Value Disclosures [Abstract]
FAIR VALUE ACCOUNTING	NOTE K—FAIR VALUE ACCOUNTING Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Fair value is estimated by applying the following hierarchy, which prioritizes the inputs used to measure fair value into three levels and bases the categorization within the hierarchy upon the lowest level of input that is available and significant to the fair value measurement: Level 1—Quoted prices in active markets for identical assets or liabilities. Level 2—Observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3—Inputs that are generally unobservable and typically reflect management’s estimate of assumptions that market participants would use in pricing the asset or liability. Cash Equivalents Due to the short-term maturity, we believe our cash equivalent instruments at March 31, 2022 and December 31, 2021, approximated their reported carrying values. Long-Term Debt, Including Current Maturities We believe that the fair values of our long-term debt, including current maturities, approximated their carrying values based on their effective interest rates compared to current market rates.

Equity-Based Compensation

Equity-Based Compensation	3 Months Ended
	Mar. 31, 2022
Share-based Payment Arrangement [Abstract]
EQUITY-BASED COMPENSATION	NOTE L—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 effective 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. We use a combination of treasury stock and new shares if necessary to satisfy option exercises or vesting of restricted awards and performance share units. Stock Options The following table summarizes the status of, and changes in, our stock option awards during the three months ended March 31, 2022: Number of Weighted Weighted Outstanding at December 31, 2021 666,718 $ 30.84 2.4 years Granted — $ — Exercised (7,500) $ 11.08 Forfeited — $ — Expired (35,695) $ 20.06 Outstanding at March 31, 2022 623,523 $ 31.70 2.3 years Exercisable at March 31, 2022 623,523 $ 31.70 2.3 years There were no grants of stock options during the three months ended March 31, 2022 and 2021. There were 7,500 and 10,164 stock options exercised during the three months ended March 31, 2022 and 2021, respectively. The total intrinsic value of stock options exercised was $25 thousand and $44 thousand for the three months ended March 31, 2022 and 2021, respectively. Cash received from stock options exercised during the three months ended March 31, 2022 and 2021 was $83 thousand and $105 thousand, respectively. The tax benefits realized from stock option exercises were $6 thousand and $11 thousand for the three months ended March 31, 2022 and 2021, respectively. As of March 31, 2022 and 2021, there was no unrecognized compensation expense related to these options. We account for forfeitures as they occur. Restricted Stock and Restricted Stock Unit Awards The following table summarizes the status of, and changes in, our unvested restricted stock awards during the three months ended March 31, 2022: Number of Shares Grant Date Weighted Unvested, December 31, 2021 1,144,310 $ 8.37 Granted 588,492 $ 9.81 Vested (111,829) $ 11.36 Forfeited (1,058) $ 13.56 Unvested, March 31, 2022 1,619,915 $ 8.68 We granted 588,492 and 633,973 restricted stock and restricted stock unit awards during the three months ended March 31, 2022 and 2021, respectively. The fair value of the awards was based on the market price of our stock at date of grant. We recognized $1.6 million and $1.6 million of equity-based compensation expense related to restricted stock and restricted stock units during the three months ended March 31, 2022 and 2021, respectively. As of March 31, 2022, there was $11.6 million of unrecognized compensation expense related to these restricted stock and restricted stock units, which is expected to be recognized over a weighted-average period of 2.2 years. We also granted cash awards during the three months ended March 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 $0.3 million and $0.4 million of expense related to these awards for the three months ended March 31, 2022 and 2021, respectively. The liability for these awards is included in accounts payable and other accrued expenses on our balance sheets. These awards will be remeasured at fair value each reporting period with resulting changes reflected in our income statements. Estimated unrecognized expense related to these awards is $1.2 million over a period of one year. Performance Share Unit Awards The following table summarizes the status of, and changes in, our performance share unit awards during the three months ended March 31, 2022: Number of Shares Grant Date Weighted Unvested, December 31, 2021 1,914,589 $ 9.77 Granted 920,681 $ 11.79 Vested (497,401) $ 14.56 Forfeited/Cancelled (658) $ 13.86 Unvested, March 31, 2022 2,337,211 $ 9.54 We granted 920,681 and 773,023 performance share unit awards during the three months ended March 31, 2022 and 2021, 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 $11.79 and $11.46 for the three months ended March 31, 2022 and 2021, 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, 2022 through December 31, 2024 for the 2022 grant, January 1, 2021 through December 31, 2023 for the 2021 grant, and from January 1, 2020 through December 31, 2022 for the 2020 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 $2.8 million and $2.5 million of compensation expense related to performance share unit awards during the three months ended March 31, 2022 and 2021, respectively. As of March 31, 2022, there was $14.6 million of unrecognized compensation expense related to these performance share unit awards, which is expected to be recognized over a weighted-average period of 2.3 years. We also granted cash awards during the three months ended March 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 $0.2 million and $0.2 million of expense related to these awards for the three months ended March 31, 2022 and 2021, respectively. The liability for these awards is included in accounts payable and other accrued expenses on our balance sheets. These awards will be remeasured at fair value each reporting period with resulting changes reflected in our income statements. Estimated unrecognized expense related to these awards is $0.4 million over a period of one year.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	NOTE M—COMMITMENTS AND CONTINGENCIES Future Minimum Annual Commitments at March 31, 2022 (in thousands): Minimum Purchase Commitments 2022 (remaining nine months) $ 6,537 2023 5,976 2024 4,295 2025 2,886 2026 2,180 Thereafter 9,288 Total future purchase commitments $ 31,162 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 three months ended March 31, 2022, zero new claims were brought against U.S. Silica. As of March 31, 2022, there were 42 active silica-related product liability claims pending in which U.S. Silica is a defendant. Although the outcomes of these claims cannot be predicted with certainty, in the opinion of management, it is not reasonably possible that the ultimate resolution of these matters will have a material adverse effect on our financial position or results of operations that exceeds the accrual amounts. We have recorded estimated liabilities for these claims in other long-term liabilities as well as estimated recoveries under the indemnity agreement and an estimate of future recoveries under insurance in other assets on our consolidated balance sheets. As of both March 31, 2022 and December 31, 2021, other non-current assets included zero for insurance for third-party product liability claims. As of both March 31, 2022 and December 31, 2021 other long-term liabilities included $0.9 million for third-party product liability claims. Obligations under Guarantees We have indemnified our insurers against any loss they may incur in the event that holders of surety bonds, issued on our behalf, execute the bonds. As of March 31, 2022, there was $40.2 million in bonds outstanding, of which $36.2 million related to reclamation requirements issued by various governmental authorities. Reclamation bonds remain outstanding until the mining area is reclaimed and the authority issues a formal release. The remaining bonds relate to licenses, permits, and tax collection.

Pension and Post-Retirement Ben

Pension and Post-Retirement Benefits	3 Months Ended
	Mar. 31, 2022
Retirement Benefits [Abstract]
PENSION AND POST-RETIREMENT BENEFITS	NOTE N—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. 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. Expenses incurred other than service costs are reported in Other income (expense) in our Condensed Consolidated Statements of Operations. Net pension benefit cost (in thousands) consisted of the following: Three Months Ended 2022 2021 Service cost $ 689 $ 805 Interest cost 689 739 Expected return on plan assets (1,418) (1,429) Net amortization and deferral 499 950 Net pension benefit costs $ 459 $ 1,065 Net post-retirement benefit cost (in thousands) consisted of the following: Three Months Ended 2022 2021 Service cost $ 6 $ 19 Interest cost 36 102 Unrecognized prior service cost (516) — Unrecognized net (gain)/loss (34) — Net post-retirement benefit costs (508) $ 121 We contributed zero and $1.3 million to the qualified pension plan for the three months ended March 31, 2022 and 2021, respectively. Our best estimates of expected contributions to the pension and post-retirement medical benefit plans for the 2022 fiscal year are zero and $1.1 million, respectively. We contribute to three multiemployer defined benefit pension plans under the terms of collective-bargaining agreements for union-represented employees. A multiemployer plan is subject to collective bargaining for employees of two or more unrelated companies. These plans allow multiple employers to pool their pension resources and realize efficiencies associated with the daily administration of the plan. Multiemployer plans are generally governed by a board of trustees composed of management and labor representatives and are funded through employer contributions. However, in most cases, management is not directly represented. Our contributions to individual multiemployer pension funds did not exceed 5% of the fund’s total contributions for the three months ended March 31, 2022 and 2021. Additionally, our contributions to multiemployer post-retirement benefit plans were immaterial for all periods presented in the accompanying condensed consolidated financial statements. We also sponsor a defined contribution plan covering certain employees. We contribute to the plan in two ways. For certain employees not covered by the defined benefit plan, we make a contribution equal to 4% of their salary. For all other eligible employees, we make a contribution up to 6% of eligible earnings.

Leases

Leases	3 Months Ended
	Mar. 31, 2022
Leases [Abstract]
Leases	NOTE O— 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. As most of our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. We have lease agreements with lease and non-lease components, the latter of which are generally accounted for separately. Supplemental balance sheet information related to leases was as follows (in thousands, except lease term and discount rate): Leases Classification March 31, December 31, 2021 Assets Operating Lease right-of-use assets $ 37,417 $ 38,793 Finance Lease right-of-use assets 4,334 3,448 Total leased assets $ 41,751 $ 42,241 Liabilities Current Operating Current portion of operating lease liabilities $ 13,158 $ 14,469 Finance Current portion of long-term debt 1,291 1,061 Non-current Operating Operating lease liabilities 71,355 75,130 Finance Long-term debt, net 3,160 2,485 Total lease liabilities $ 88,964 $ 93,145 Lease Term and Discount Rate Weighted average remaining lease term: Operating 6.7 years 6.9 years Finance 4.2 years 3.6 years Weighted average discount rate: Operating 5.7% 5.7% Finance 5.0% 5.1% The components of lease expense (in thousands) were as follows: Lease Costs Classification Three Months Ended Three Months Ended Operating lease costs (1) Cost of sales $ 7,628 $ 8,137 Operating lease costs (2) Selling, general and administrative 354 528 Total (3) $ 7,982 $ 8,665 (1) Included short-term operating lease costs of $4.7 million and $3.7 million for the three months ended March 31, 2022 and 2021, respectively. (2) Included short-term operating lease costs of $0.1 million for both the three months ended March 31, 2022 and 2021, respectively. (3) Not included were expenses for finance leases of $0.4 million and $45 thousand for the three months ended March 31, 2022 and 2021, respectively. Supplemental cash flow information (in thousands) related to leases was as follows: Three Months Ended Three Months Ended Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows for operating leases $ 7,518 $ 8,159 Financing cash flows for finance leases $ 330 $ 45 Right-of-use assets obtained in exchange for new lease liabilities: Operating leases $ 1,188 $ 1,306 Finance leases $ 2,102 $ 843 Maturities of lease liabilities (in thousands) as of March 31, 2022: Operating leases Finance leases 2022 (remaining nine months) $ 13,004 $ 1,109 2023 20,958 1,469 2024 17,014 1,154 2025 13,347 805 2026 11,474 271 Thereafter 31,855 33 Total lease payments $ 107,652 $ 4,841 Less: Interest 19,696 390 Less: Other operating expenses 3,443 — Total $ 84,513 $ 4,451
Leases	NOTE O— 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. As most of our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. We have lease agreements with lease and non-lease components, the latter of which are generally accounted for separately. Supplemental balance sheet information related to leases was as follows (in thousands, except lease term and discount rate): Leases Classification March 31, December 31, 2021 Assets Operating Lease right-of-use assets $ 37,417 $ 38,793 Finance Lease right-of-use assets 4,334 3,448 Total leased assets $ 41,751 $ 42,241 Liabilities Current Operating Current portion of operating lease liabilities $ 13,158 $ 14,469 Finance Current portion of long-term debt 1,291 1,061 Non-current Operating Operating lease liabilities 71,355 75,130 Finance Long-term debt, net 3,160 2,485 Total lease liabilities $ 88,964 $ 93,145 Lease Term and Discount Rate Weighted average remaining lease term: Operating 6.7 years 6.9 years Finance 4.2 years 3.6 years Weighted average discount rate: Operating 5.7% 5.7% Finance 5.0% 5.1% The components of lease expense (in thousands) were as follows: Lease Costs Classification Three Months Ended Three Months Ended Operating lease costs (1) Cost of sales $ 7,628 $ 8,137 Operating lease costs (2) Selling, general and administrative 354 528 Total (3) $ 7,982 $ 8,665 (1) Included short-term operating lease costs of $4.7 million and $3.7 million for the three months ended March 31, 2022 and 2021, respectively. (2) Included short-term operating lease costs of $0.1 million for both the three months ended March 31, 2022 and 2021, respectively. (3) Not included were expenses for finance leases of $0.4 million and $45 thousand for the three months ended March 31, 2022 and 2021, respectively. Supplemental cash flow information (in thousands) related to leases was as follows: Three Months Ended Three Months Ended Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows for operating leases $ 7,518 $ 8,159 Financing cash flows for finance leases $ 330 $ 45 Right-of-use assets obtained in exchange for new lease liabilities: Operating leases $ 1,188 $ 1,306 Finance leases $ 2,102 $ 843 Maturities of lease liabilities (in thousands) as of March 31, 2022: Operating leases Finance leases 2022 (remaining nine months) $ 13,004 $ 1,109 2023 20,958 1,469 2024 17,014 1,154 2025 13,347 805 2026 11,474 271 Thereafter 31,855 33 Total lease payments $ 107,652 $ 4,841 Less: Interest 19,696 390 Less: Other operating expenses 3,443 — Total $ 84,513 $ 4,451

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2022
Income Tax Disclosure [Abstract]
INCOME TAXES	NOTE P— INCOME TAXES For interim period reporting, we record income taxes using an estimated annual effective tax rate based upon projected annual income, forecasted permanent tax differences, discrete items and statutory rates in states in which we operate. At the end of each interim period, we update the estimated annual effective tax rate, and if the estimated tax rate changes based on new information, we make a cumulative adjustment in the period. We record the tax effect of an unusual or infrequently occurring item in the interim period in which it occurs as a discrete item of tax. On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (the “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 which generated 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 which generated a refund of $26.3 million, of which $4.9 million was received during the fourth quarter of 2020 and $21.1 million was received during the first quarter of 2022. At March 31, 2022, the remaining $0.4 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. Pursuant to ASC 740, this was recorded as a discrete component of the tax benefit. For the three months ended March 31, 2022 and 2021, we had tax benefits of $7.0 million and $4.4 million, respectively. The effective tax rates were 45% and 17% for the three months ended March 31, 2022 and 2021, respectively. Without discrete items, which primarily consist of tax expense related to equity compensation and tax benefits related to the carryback of NOLs described above, the effective tax rates for the three months ended March 31, 2022 and 2021 would have been 48% and 24%, respectively.

Revenue

Revenue	3 Months Ended
	Mar. 31, 2022
Revenue from Contract with Customer [Abstract]
REVENUE	NOTE Q— REVENUE We consider sales disaggregated at the product and service level by business segment to depict how the nature, amount, timing and uncertainty of revenues and cash flow are impacted by changes in economic factors. The following table disaggregates our sales by major source (in thousands): Three Months Ended Three Months Ended Category Oil & Gas Proppants Industrial & Specialty Products Total Sales Oil & Gas Proppants Industrial & Specialty Products Total Sales Product $ 104,591 $ 128,643 $ 233,234 $ 78,671 $ 112,719 $ 191,390 Service 71,653 — 71,653 43,026 — 43,026 Total Sales $ 176,244 $ 128,643 $ 304,887 $ 121,697 $ 112,719 $ 234,416 The following tables reflect the changes in our contract assets, which we classify as unbilled receivables and our contract liabilities, which we classify as deferred revenues, for the three months ended March 31, 2022 and 2021 (in thousands): Unbilled Receivables March 31, 2022 March 31, 2021 Beginning Balance $ 1,957 $ 47,982 Reclassifications to billed receivables (1,957) (512) Revenues recognized in excess of period billings 2,500 1,647 Ending Balance $ 2,500 $ 49,117 Deferred Revenue March 31, 2022 March 31, 2021 Beginning Balance $ 20,741 $ 33,692 Revenues recognized from balances held at the beginning of the period (1,653) (4,256) Revenues deferred from period collections on unfulfilled performance obligations 450 3,368 Revenues recognized from period collections (404) (876) Ending Balance $ 19,134 $ 31,928 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. 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. As of June 30, 2021, $43.9 million was included in unbilled receivables and $1.1 million was included in billed receivables related to this settlement. These amounts were received in full during the third quarter of 2021. Foreign Operations The following table includes information related to our foreign operations (in thousands): Three Months Ended Three Months Ended Total Sales $ 25,254 $ 21,696 Pre-tax income $ 4,813 $ 4,138 Net income $ 3,802 $ 3,269 Foreign operations constituted approximately $34.2 million and $27.6 million of consolidated assets as of March 31, 2022 and 2021, respectively.

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2022
Related Party Transactions [Abstract]
RELATED PARTY TRANSACTIONS	NOTE R— RELATED PARTY TRANSACTIONS There were no related party transactions during the three months ended March 31, 2022 or 2021.

Segment Reporting

Segment Reporting	3 Months Ended
	Mar. 31, 2022
Segment Reporting [Abstract]
SEGMENT REPORTING	NOTE S— SEGMENT REPORTING Our business is organized into two reportable segments, Oil & Gas Proppants and Industrial & Specialty Products, based on end markets. The reportable segments are consistent with how management views the markets that we serve and the financial information reviewed by the chief operating decision maker. We manage our Oil & Gas Proppants and Industrial & Specialty Products businesses as components of an enterprise for which separate information is available and is evaluated regularly by the chief operating decision maker in deciding how to allocate resources and assess performance. 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 industries, including container glass, fiberglass, specialty glass, flat glass, building products, fillers and extenders, foundry products, chemicals, recreation products and filtration products. An operating segment’s performance is primarily evaluated based on segment contribution margin, which excludes selling, general, and administrative costs, corporate costs, plant capacity expansion expenses, and facility closure costs. We believe that segment contribution margin, as defined above, is an appropriate measure for evaluating the operating performance of our segments. However, segment contribution margin is a non-GAAP measure and should be considered in addition to, not a substitute for, or superior to, net income (loss) or other measures of financial performance prepared in accordance with GAAP. The other accounting policies of each of the two reportable segments are the same as those in Note B - Summary of Significant Accounting Policies to the Consolidated Financial Statements in Item 8 of our 2021 Annual Report on Form 10-K. The following table presents sales and segment contribution margin (in thousands) for the reportable segments and other operating results not allocated to the reportable segments: Three Months Ended 2022 2021 Sales: Oil & Gas Proppants $ 176,244 $ 121,697 Industrial & Specialty Products 128,643 112,719 Total sales 304,887 234,416 Segment contribution margin: Oil & Gas Proppants 44,753 21,540 Industrial & Specialty Products 37,834 40,038 Total segment contribution margin 82,587 61,578 Operating activities excluded from segment cost of sales (4,569) (4,151) Selling, general and administrative (40,110) (26,224) Depreciation, depletion and amortization (37,749) (41,348) Goodwill and other asset impairments — (38) Interest expense (17,173) (17,711) Other income, net, including interest income 1,531 2,605 Income tax benefit 6,969 4,354 Net loss $ (8,514) $ (20,935) Less: Net loss attributable to non-controlling interest (121) (157) Net loss attributable to U.S. Silica Holdings, Inc. $ (8,393) $ (20,778)

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2022
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	NOTE T— SUBSEQUENT EVENTS Subsequent to quarter end, we executed a minimum purchase supply agreement with an Oil & Gas Proppants segment customer. This agreement included a $20.0 million capacity reservation fee, which we will receive in cash during the second quarter.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Basis of Presentation	The accompanying unaudited Condensed Consolidated Financial Statements for the quarter ended March 31, 2022 included in this Quarterly Report on Form 10-Q have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X issued by the U.S. Securities and Exchange Commission (“SEC”). They do not contain certain information included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2021; therefore, the unaudited Condensed Consolidated Financial Statements should be read in conjunction with that Annual Report on Form 10-K. Operating results for the three-month period ended March 31, 2022 are not necessarily indicative of the results that may be expected for the full year ending December 31, 2022. In the opinion of management, all adjustments necessary for a fair presentation have been included. Such adjustments are of a normal, recurring nature.
Consolidation	The unaudited Condensed Consolidated Financial Statements include the accounts of Holdings and its direct and indirect wholly-owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation.
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.
New Accounting Pronouncements Recently Adopted and New Accounting Pronouncements Not Yet Adopted	New Accounting Pronouncements Recently Adopted None. New Accounting Pronouncements Not Yet Adopted In March 2020, the FASB issued Accounting Standards Update ("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 March 31, 2022, 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 I - Debt for discussion of the use of the adjusted LIBOR rate in connection with borrowings under our senior secured revolving credit facility.
Fair Value Accounting	Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Fair value is estimated by applying the following hierarchy, which prioritizes the inputs used to measure fair value into three levels and bases the categorization within the hierarchy upon the lowest level of input that is available and significant to the fair value measurement: Level 1—Quoted prices in active markets for identical assets or liabilities. Level 2—Observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3—Inputs that are generally unobservable and typically reflect management’s estimate of assumptions that market participants would use in pricing the asset or liability. Cash Equivalents Due to the short-term maturity, we believe our cash equivalent instruments at March 31, 2022 and December 31, 2021, approximated their reported carrying values. Long-Term Debt, Including Current Maturities We believe that the fair values of our long-term debt, including current maturities, approximated their carrying values based on their effective interest rates compared to current market rates.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2022
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 Three Months Ended 2022 2021 Numerator: Net loss attributable to U.S. Silica Holdings, Inc. $ (8,393) $ (20,778) Denominator: Weighted average shares outstanding 75,240 73,927 Diluted effect of stock awards — — Weighted average shares outstanding assuming dilution 75,240 73,927 Loss per share attributable to U.S. Silica Holdings, Inc.: Basic loss per share $ (0.11) $ (0.28) Diluted loss per share $ (0.11) $ (0.28)
Schedule of Potentially Dilutive Shares Excluded from Computation of Diluted Earnings Per Share	Such potentially dilutive shares and stock awards excluded from the calculation of diluted earnings per common share were as follows: In thousands Three Months Ended 2022 2021 Potentially dilutive shares excluded 1,808 1,852 Stock options excluded 541 608 Restricted stock and performance share unit awards excluded 12 50

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	3 Months Ended
	Mar. 31, 2022
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 Three Months Ended March 31, 2022 Foreign currency translation adjustments Pension and other post-retirement benefits liability Total Beginning Balance $ (417) $ 766 $ 349 Other comprehensive (loss) gain before reclassifications (309) 3,494 3,185 Amounts reclassified from accumulated other comprehensive income — (32) (32) Ending Balance $ (726) $ 4,228 $ 3,502

Accounts Receivable (Tables)

Accounts Receivable (Tables)	3 Months Ended
	Mar. 31, 2022
Receivables [Abstract]
Schedule of Accounts Receivable and Allowance for Credit Losses	Accounts receivable (in thousands) consisted of the following: March 31, December 31, Trade receivables $ 201,081 $ 182,992 Less: Allowance for credit losses (5,511) (5,248) Net trade receivables 195,570 177,744 Other receivables (1) 3,265 25,015 Total accounts receivable $ 198,835 $ 202,759 (1) Other receivables included $0.4 million and $21.5 million at March 31, 2022 and December 31, 2021, respectively, 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): Oil & Gas Proppants Industrial & Specialty Products Total Beginning balance, December 31, 2021 $ 4,625 $ 623 $ 5,248 Allowance for credit losses — 286 286 Write-offs — (23) (23) Ending balance, March 31, 2022 $ 4,625 $ 886 $ 5,511

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Mar. 31, 2022
Inventory Disclosure [Abstract]
Schedule of Inventories	Inventories (in thousands) consisted of the following: March 31, 2022 December 31, 2021 Supplies $ 49,224 $ 45,605 Raw materials and work in process 36,542 36,529 Finished goods 38,018 33,579 Total inventories $ 123,784 $ 115,713

Property, Plant and Mine Deve_2

Property, Plant and Mine Development (Tables)	3 Months Ended
	Mar. 31, 2022
Property, Plant and Equipment [Abstract]
Schedule of Property, Plant and Mine Development	Property, plant and mine development (in thousands) consisted of the following: March 31, December 31, Mining property and mine development $ 788,441 $ 789,122 Asset retirement cost 19,937 22,283 Land 55,551 55,541 Land improvements 76,248 76,248 Buildings 72,252 72,207 Machinery and equipment 1,193,025 1,189,548 Furniture and fixtures 3,932 3,932 Construction-in-progress 36,264 35,060 2,245,650 2,243,941 Accumulated depreciation, depletion, amortization and impairment charges (1,017,579) (985,295) Total property, plant and mine development, net $ 1,228,071 $ 1,258,646

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Carrying Amount of Goodwill by Business Segment	The changes in the carrying amount of goodwill (in thousands) by business segment consisted of the following: Oil & Gas Proppants Segment Industrial & Specialty Products Segment Totals Balance at December 31, 2021 $ — $ 185,649 $ 185,649 Impairment loss — — — Balance at March 31, 2022 $ — $ 185,649 $ 185,649
Schedule of Changes in the Carrying Amount of Definite-Lived Intangible Assets	The changes in the carrying amount of intangible assets (in thousands) consisted of the following: March 31, 2022 December 31, 2021 Gross Carrying Amount Accumulated Amortization Impairments Net Gross Carrying Amount Accumulated Amortization Impairments Net Technology and intellectual property $ 71,270 $ (26,329) $ — $ 44,941 $ 71,209 $ (25,069) $ (38) $ 46,102 Customer relationships 66,999 (29,186) — 37,813 66,999 (27,987) — 39,012 Total definite-lived intangible assets: $ 138,269 $ (55,515) $ — $ 82,754 $ 138,208 $ (53,056) $ (38) $ 85,114 Trade names 64,240 — — 64,240 64,240 — — 64,240 Other 700 — — 700 700 — — 700 Total intangible assets: $ 203,209 $ (55,515) $ — $ 147,694 $ 203,148 $ (53,056) $ (38) $ 150,054
Schedule of Changes in the Carrying Amount of Indefinite-Lived Intangible Assets	The changes in the carrying amount of intangible assets (in thousands) consisted of the following: March 31, 2022 December 31, 2021 Gross Carrying Amount Accumulated Amortization Impairments Net Gross Carrying Amount Accumulated Amortization Impairments Net Technology and intellectual property $ 71,270 $ (26,329) $ — $ 44,941 $ 71,209 $ (25,069) $ (38) $ 46,102 Customer relationships 66,999 (29,186) — 37,813 66,999 (27,987) — 39,012 Total definite-lived intangible assets: $ 138,269 $ (55,515) $ — $ 82,754 $ 138,208 $ (53,056) $ (38) $ 85,114 Trade names 64,240 — — 64,240 64,240 — — 64,240 Other 700 — — 700 700 — — 700 Total intangible assets: $ 203,209 $ (55,515) $ — $ 147,694 $ 203,148 $ (53,056) $ (38) $ 150,054
Schedule of Estimated Amortization Expense Related to Definite-Lived Intangible Assets	The estimated amortization expense related to definite-lived intangible assets (in thousands) for the five succeeding years is as follows: 2022 (remaining nine months) $ 7,249 2023 $ 9,665 2024 $ 9,665 2025 $ 9,665 2026 $ 9,665

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2022
Debt Disclosure [Abstract]
Schedule of Debt	Debt (in thousands) consisted of the following: March 31, December 31, Senior secured credit facility: Revolver expiring May 1, 2023 (4.50% at March 31, 2022 and 4.13% at December 31, 2021) $ — $ — Term Loan—final maturity May 1, 2025 (5.00% at March 31, 2022 and 5.00% at December 31, 2021) 1,218,662 1,222,000 Less: Unamortized original issue discount (3,095) (3,350) Less: Unamortized debt issuance cost (13,947) (15,200) Insurance financing notes payable 2,212 4,424 Finance leases (See Note O - Leases) 4,451 3,546 Total debt 1,208,283 1,211,420 Less: current portion (16,303) (18,285) Total long-term portion of debt $ 1,191,980 $ 1,193,135
Schedule of Contractual Maturities of Term Loan	At March 31, 2022, contractual maturities of our Term Loan (in thousands) are as follows: 2022 (remaining nine months) $ 9,600 2023 12,800 2024 12,800 2025 1,183,462 2026 — Thereafter — Total $ 1,218,662

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	3 Months Ended
	Mar. 31, 2022
Asset Retirement Obligation Disclosure [Abstract]
Schedule of Changes in Asset Retirement Obligations	Changes in the asset retirement obligations (in thousands) are as follows: Three Months Ended 2022 2021 Beginning balance $ 32,049 $ 24,717 Accretion 374 342 Additions and revisions of estimates (3,126) 279 Ending balance $ 29,297 $ 25,338

Equity-Based Compensation (Tabl

Equity-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2022
Share-based Payment Arrangement [Abstract]
Schedule of Stock Options Activity	The following table summarizes the status of, and changes in, our stock option awards during the three months ended March 31, 2022: Number of Weighted Weighted Outstanding at December 31, 2021 666,718 $ 30.84 2.4 years Granted — $ — Exercised (7,500) $ 11.08 Forfeited — $ — Expired (35,695) $ 20.06 Outstanding at March 31, 2022 623,523 $ 31.70 2.3 years Exercisable at March 31, 2022 623,523 $ 31.70 2.3 years
Schedule of Restricted Stock, Restricted Stock Unit and Performance Share Unit Awards Activity	The following table summarizes the status of, and changes in, our unvested restricted stock awards during the three months ended March 31, 2022: Number of Shares Grant Date Weighted Unvested, December 31, 2021 1,144,310 $ 8.37 Granted 588,492 $ 9.81 Vested (111,829) $ 11.36 Forfeited (1,058) $ 13.56 Unvested, March 31, 2022 1,619,915 $ 8.68 The following table summarizes the status of, and changes in, our performance share unit awards during the three months ended March 31, 2022: Number of Shares Grant Date Weighted Unvested, December 31, 2021 1,914,589 $ 9.77 Granted 920,681 $ 11.79 Vested (497,401) $ 14.56 Forfeited/Cancelled (658) $ 13.86 Unvested, March 31, 2022 2,337,211 $ 9.54

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Annual Commitments	Future Minimum Annual Commitments at March 31, 2022 (in thousands): Minimum Purchase Commitments 2022 (remaining nine months) $ 6,537 2023 5,976 2024 4,295 2025 2,886 2026 2,180 Thereafter 9,288 Total future purchase commitments $ 31,162

Pension and Post-Retirement B_2

Pension and Post-Retirement Benefits (Tables)	3 Months Ended
	Mar. 31, 2022
Retirement Benefits [Abstract]
Schedule of Net Pension and Post-Retirement Benefit Plans	Net pension benefit cost (in thousands) consisted of the following: Three Months Ended 2022 2021 Service cost $ 689 $ 805 Interest cost 689 739 Expected return on plan assets (1,418) (1,429) Net amortization and deferral 499 950 Net pension benefit costs $ 459 $ 1,065 Net post-retirement benefit cost (in thousands) consisted of the following: Three Months Ended 2022 2021 Service cost $ 6 $ 19 Interest cost 36 102 Unrecognized prior service cost (516) — Unrecognized net (gain)/loss (34) — Net post-retirement benefit costs (508) $ 121

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2022
Leases [Abstract]
Schedule of Supplemental Balance Sheet Information	Supplemental balance sheet information related to leases was as follows (in thousands, except lease term and discount rate): Leases Classification March 31, December 31, 2021 Assets Operating Lease right-of-use assets $ 37,417 $ 38,793 Finance Lease right-of-use assets 4,334 3,448 Total leased assets $ 41,751 $ 42,241 Liabilities Current Operating Current portion of operating lease liabilities $ 13,158 $ 14,469 Finance Current portion of long-term debt 1,291 1,061 Non-current Operating Operating lease liabilities 71,355 75,130 Finance Long-term debt, net 3,160 2,485 Total lease liabilities $ 88,964 $ 93,145 Lease Term and Discount Rate Weighted average remaining lease term: Operating 6.7 years 6.9 years Finance 4.2 years 3.6 years Weighted average discount rate: Operating 5.7% 5.7% Finance 5.0% 5.1%
Schedule of Components of Lease Expense and Supplemental Cash Flow Information	The components of lease expense (in thousands) were as follows: Lease Costs Classification Three Months Ended Three Months Ended Operating lease costs (1) Cost of sales $ 7,628 $ 8,137 Operating lease costs (2) Selling, general and administrative 354 528 Total (3) $ 7,982 $ 8,665 (1) Included short-term operating lease costs of $4.7 million and $3.7 million for the three months ended March 31, 2022 and 2021, respectively. (2) Included short-term operating lease costs of $0.1 million for both the three months ended March 31, 2022 and 2021, respectively. (3) Not included were expenses for finance leases of $0.4 million and $45 thousand for the three months ended March 31, 2022 and 2021, respectively. Supplemental cash flow information (in thousands) related to leases was as follows: Three Months Ended Three Months Ended Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows for operating leases $ 7,518 $ 8,159 Financing cash flows for finance leases $ 330 $ 45 Right-of-use assets obtained in exchange for new lease liabilities: Operating leases $ 1,188 $ 1,306 Finance leases $ 2,102 $ 843
Schedule of Maturity of Operating Lease Liabilities	Maturities of lease liabilities (in thousands) as of March 31, 2022: Operating leases Finance leases 2022 (remaining nine months) $ 13,004 $ 1,109 2023 20,958 1,469 2024 17,014 1,154 2025 13,347 805 2026 11,474 271 Thereafter 31,855 33 Total lease payments $ 107,652 $ 4,841 Less: Interest 19,696 390 Less: Other operating expenses 3,443 — Total $ 84,513 $ 4,451
Schedule of Maturity of Finance Lease Liabilities	Maturities of lease liabilities (in thousands) as of March 31, 2022: Operating leases Finance leases 2022 (remaining nine months) $ 13,004 $ 1,109 2023 20,958 1,469 2024 17,014 1,154 2025 13,347 805 2026 11,474 271 Thereafter 31,855 33 Total lease payments $ 107,652 $ 4,841 Less: Interest 19,696 390 Less: Other operating expenses 3,443 — Total $ 84,513 $ 4,451

Revenue (Tables)

Revenue (Tables)	3 Months Ended
	Mar. 31, 2022
Revenue from Contract with Customer [Abstract]
Schedule of Sales by Major Source	The following table disaggregates our sales by major source (in thousands): Three Months Ended Three Months Ended Category Oil & Gas Proppants Industrial & Specialty Products Total Sales Oil & Gas Proppants Industrial & Specialty Products Total Sales Product $ 104,591 $ 128,643 $ 233,234 $ 78,671 $ 112,719 $ 191,390 Service 71,653 — 71,653 43,026 — 43,026 Total Sales $ 176,244 $ 128,643 $ 304,887 $ 121,697 $ 112,719 $ 234,416
Schedule of Changes in Contract Assets and Liabilities	The following tables reflect the changes in our contract assets, which we classify as unbilled receivables and our contract liabilities, which we classify as deferred revenues, for the three months ended March 31, 2022 and 2021 (in thousands): Unbilled Receivables March 31, 2022 March 31, 2021 Beginning Balance $ 1,957 $ 47,982 Reclassifications to billed receivables (1,957) (512) Revenues recognized in excess of period billings 2,500 1,647 Ending Balance $ 2,500 $ 49,117 Deferred Revenue March 31, 2022 March 31, 2021 Beginning Balance $ 20,741 $ 33,692 Revenues recognized from balances held at the beginning of the period (1,653) (4,256) Revenues deferred from period collections on unfulfilled performance obligations 450 3,368 Revenues recognized from period collections (404) (876) Ending Balance $ 19,134 $ 31,928
Schedule of Total Sales, Pre-tax Income and Net Income Related to Foreign Operations	The following table includes information related to our foreign operations (in thousands): Three Months Ended Three Months Ended Total Sales $ 25,254 $ 21,696 Pre-tax income $ 4,813 $ 4,138 Net income $ 3,802 $ 3,269

Segment Reporting (Tables)

Segment Reporting (Tables)	3 Months Ended
	Mar. 31, 2022
Segment Reporting [Abstract]
Schedule of Sales and Segment Contribution Margin for Reporting Segments and Operating Results	The following table presents sales and segment contribution margin (in thousands) for the reportable segments and other operating results not allocated to the reportable segments: Three Months Ended 2022 2021 Sales: Oil & Gas Proppants $ 176,244 $ 121,697 Industrial & Specialty Products 128,643 112,719 Total sales 304,887 234,416 Segment contribution margin: Oil & Gas Proppants 44,753 21,540 Industrial & Specialty Products 37,834 40,038 Total segment contribution margin 82,587 61,578 Operating activities excluded from segment cost of sales (4,569) (4,151) Selling, general and administrative (40,110) (26,224) Depreciation, depletion and amortization (37,749) (41,348) Goodwill and other asset impairments — (38) Interest expense (17,173) (17,711) Other income, net, including interest income 1,531 2,605 Income tax benefit 6,969 4,354 Net loss $ (8,514) $ (20,935) Less: Net loss attributable to non-controlling interest (121) (157) Net loss attributable to U.S. Silica Holdings, Inc. $ (8,393) $ (20,778)

Organization and Basis of Pre_2

Organization and Basis of Presentation (Details)	3 Months Ended
	Mar. 31, 2022segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of reportable segments	2

Earnings Per Share - Computatio

Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Numerator:
Net loss attributable to U.S. Silica Holdings, Inc.	$ (8,393)	$ (20,778)
Denominator:
Weighted average shares outstanding (in shares)	75,240	73,927
Diluted effect of stock awards (in shares)	0	0
Weighted average shares outstanding assuming dilution (shares)	75,240	73,927
Loss per share attributable to U.S. Silica Holdings, Inc.:
Basic loss per share (in dollars per share)	$ (0.11)	$ (0.28)
Diluted loss per share (in dollars per share)	$ (0.11)	$ (0.28)

Earnings Per Share - Potentiall

Earnings Per Share - Potentially Dilutive Shares Excluded From Calculation of Diluted Earnings Per Share (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Potentially dilutive shares excluded
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares excluded from calculation of weighted average shares outstanding and diluted earnings per share (in shares)	1,808	1,852
Stock options excluded
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares excluded from calculation of weighted average shares outstanding and diluted earnings per share (in shares)	541	608
Restricted stock and performance share unit awards excluded
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares excluded from calculation of weighted average shares outstanding and diluted earnings per share (in shares)	12	50

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022USD ($)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	$ 614,083
Other comprehensive (loss) gain before reclassifications	3,185
Amounts reclassified from accumulated other comprehensive income	(32)
Ending Balance	610,794
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(417)
Other comprehensive (loss) gain before reclassifications	(309)
Amounts reclassified from accumulated other comprehensive income	0
Ending Balance	(726)
Pension and other post-retirement benefits liability
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	766
Other comprehensive (loss) gain before reclassifications	3,494
Amounts reclassified from accumulated other comprehensive income	(32)
Ending Balance	4,228
Total
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	349
Ending Balance	$ 3,502

Accounts Receivable - Summary o

Accounts Receivable - Summary of Accounts Receivable (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Receivables [Abstract]
Trade receivables	$ 201,081	$ 182,992
Less: Allowance for credit losses	(5,511)	(5,248)
Net trade receivables	195,570	177,744
Other receivables	3,265	25,015
Total accounts receivable	198,835	202,759
Refundable NOL carryback claims filed in accordance with CARES Act provisions	$ 400	$ 21,500

Accounts Receivable - Changes i

Accounts Receivable - Changes in Allowance for Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Allowance for Doubtful Accounts Receivable Roll Forward
Beginning balance, December 31, 2021	$ 5,248
Allowance for credit losses	286	$ 10
Write-offs	(23)
Ending balance, March 31, 2022	5,511
Oil & Gas Proppants
Allowance for Doubtful Accounts Receivable Roll Forward
Beginning balance, December 31, 2021	4,625
Allowance for credit losses	0
Write-offs	0
Ending balance, March 31, 2022	4,625
Industrial & Specialty Products
Allowance for Doubtful Accounts Receivable Roll Forward
Beginning balance, December 31, 2021	623
Allowance for credit losses	286
Write-offs	(23)
Ending balance, March 31, 2022	$ 886

Accounts Receivable - Narrative

Accounts Receivable - Narrative (Details)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Customer Concentration Risk | Sales | Ten Largest Customers
Concentration Risk [Line Items]
Concentration risk percentage	40.00%	42.00%

Inventories (Details)

Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Inventory Disclosure [Abstract]
Supplies	$ 49,224	$ 45,605
Raw materials and work in process	36,542	36,529
Finished goods	38,018	33,579
Total inventories	$ 123,784	$ 115,713

Property, Plant and Mine Deve_3

Property, Plant and Mine Development - Schedule (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment
Property, plant and mine development, gross	$ 2,245,650	$ 2,243,941
Accumulated depreciation, depletion, amortization and impairment charges	(1,017,579)	(985,295)
Total property, plant and mine development, net	1,228,071	1,258,646
Mining property and mine development
Property, Plant and Equipment
Property, plant and mine development, gross	788,441	789,122
Asset retirement cost
Property, Plant and Equipment
Property, plant and mine development, gross	19,937	22,283
Land
Property, Plant and Equipment
Property, plant and mine development, gross	55,551	55,541
Land improvements
Property, Plant and Equipment
Property, plant and mine development, gross	76,248	76,248
Buildings
Property, Plant and Equipment
Property, plant and mine development, gross	72,252	72,207
Machinery and equipment
Property, Plant and Equipment
Property, plant and mine development, gross	1,193,025	1,189,548
Furniture and fixtures
Property, Plant and Equipment
Property, plant and mine development, gross	3,932	3,932
Construction-in-progress
Property, Plant and Equipment
Property, plant and mine development, gross	$ 36,264	$ 35,060

Property, Plant and Mine Deve_4

Property, Plant and Mine Development - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 34.8	$ 38.6

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Carrying Amount of Goodwill by Business Segment (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022USD ($)
Goodwill [Roll Forward]
Balance at December 31, 2021	$ 185,649
Impairment loss	0
Balance at March 31, 2022	185,649
Oil & Gas Proppants Segment
Goodwill [Roll Forward]
Balance at December 31, 2021	0
Impairment loss	0
Balance at March 31, 2022	0
Industrial & Specialty Products | Industrial & Specialty Products
Goodwill [Roll Forward]
Balance at December 31, 2021	185,649
Impairment loss	0
Balance at March 31, 2022	$ 185,649

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Carrying Amount of Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 138,269	$ 138,208
Accumulated Amortization	(55,515)	(53,056)
Impairments	0	(38)
Net	82,754	85,114
Total Intangible Assets
Gross Carrying Amount	203,209	203,148
Accumulated Amortization	(55,515)	(53,056)
Impairments	0	(38)
Net	147,694	150,054
Trade names
Indefinite-lived Intangible Assets
Gross Carrying Amount	64,240	64,240
Impairments	0	0
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 [Line Items]
Gross Carrying Amount	71,270	71,209
Accumulated Amortization	(26,329)	(25,069)
Impairments	0	(38)
Net	44,941	46,102
Total Intangible Assets
Accumulated Amortization	(26,329)	(25,069)
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	66,999	66,999
Accumulated Amortization	(29,186)	(27,987)
Impairments	0	0
Net	37,813	39,012
Total Intangible Assets
Accumulated Amortization	$ (29,186)	$ (27,987)

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment	$ 0
Amortization expense of intangibles	$ 2,400,000	$ 2,400,000
Technology and intellectual property
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives of intangibles	15 years
Customer relationships | Minimum
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives of intangibles	13 years
Customer relationships | Maximum
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives of intangibles	20 years
Oil & Gas Proppants | COVID-19
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment	$ 0

Goodwill and Intangible Asset_5

Goodwill and Intangible Assets - Estimated Amortization Expense Related to Definite-Lived Intangible Assets (Details) $ in Thousands	Mar. 31, 2022USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2022 (remaining nine months)	$ 7,249
2023	9,665
2024	9,665
2025	9,665
2026	$ 9,665

Debt - Schedule (Details)

Debt - Schedule (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Line of Credit Facility
Less: Unamortized original issue discount	$ (3,095)	$ (3,350)
Less: Unamortized debt issuance cost	(13,947)	(15,200)
Finance leases (See Note O - Leases)	4,451	3,546
Total debt	1,208,283	1,211,420
Less: current portion	(16,303)	(18,285)
Total long-term portion of debt	1,191,980	1,193,135
Notes Payable | Insurance financing notes payable
Line of Credit Facility
Insurance financing notes payable	$ 2,212	$ 4,424
Revolving Line-of-Credit | Revolver expiring May 1, 2023 (4.50% at March 31, 2022 and 4.13% at December 31, 2021)
Line of Credit Facility
Interest rate	4.50%	4.13%
Long-term debt	$ 0	$ 0
Senior Secured Credit Facility | Term Loan—final maturity May 1, 2025 (5.00% at March 31, 2022 and 5.00% at December 31, 2021)
Line of Credit Facility
Interest rate	5.00%	5.00%
Long-term debt	$ 1,218,662	$ 1,222,000

Debt - Narrative (Details)

Debt - Narrative (Details)	May 01, 2018USD ($)	Mar. 31, 2022USD ($)	Dec. 31, 2021USD ($)	Sep. 30, 2021
Insurance financing notes payable | Notes Payable
Debt Instrument [Line Items]
Debt interest rate percentage				2.90%
Notes payable balance		$ 2,212,000	$ 4,424,000
Revolving Line-of-Credit | Revolver
Debt Instrument [Line Items]
Available borrowing base		100,000,000
Amount drawn from borrowing base		0
Amount available under the line of credit		$ 78,400,000
Actual consolidated leverage ratio		5.07
Amount available under the line of credit without consent of the lenders		$ 30,000,000
Letter of Credit | Revolver
Debt Instrument [Line Items]
Amount allocated for letters of credit		$ 21,600,000
Senior Secured Credit Facility
Debt Instrument [Line Items]
Debt issued	$ 1,380,000,000
Capitalized debt issuance costs and original issue discount	38,700,000
Senior Secured Credit Facility | Term Loan
Debt Instrument [Line Items]
Debt issued	1,280,000,000
Senior Secured Credit Facility | Revolving Line-of-Credit | Revolver
Debt Instrument [Line Items]
Debt issued	$ 100,000,000
Credit facility consolidated total net leverage ratio	3.75
Net leverage ratio, credit facility threshold percentage	30.00%

Debt - Contractual Maturities o

Debt - Contractual Maturities of Term Loan (Details) - Senior Secured Credit Facility - Term Loan - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
2022 (remaining nine months)	$ 9,600
2023	12,800
2024	12,800
2025	1,183,462
2026	0
Thereafter	0
Total	$ 1,218,662	$ 1,222,000

Asset Retirement Obligations (D

Asset Retirement Obligations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance	$ 32,049	$ 24,717
Accretion	374	342
Additions and revisions of estimates	(3,126)	279
Ending balance	$ 29,297	$ 25,338

Equity-Based Compensation - Nar

Equity-Based Compensation - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants of stock options (in shares)	0	0
Stock options exercised (in shares)	7,500	10,164
Intrinsic value of stock options exercised	$ 25,000	$ 44,000
Cash received from options exercised	83,000	105,000
Tax benefit realized from stock options exercised	6,000	11,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense related to stock options	$ 0	$ 0
Restricted Stock and Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)	588,492	633,973
Granted (in dollars per share)	$ 9.81
Recognized equity-based compensation	$ 1,600,000	$ 1,600,000
Unrecognized compensation expense related to awards	$ 11,600,000
Recognized weighted-average period	2 years 2 months 12 days
Restricted Stock and Restricted Stock Units Cash Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized equity-based compensation	$ 300,000	$ 400,000
Unrecognized compensation expense related to awards	$ 1,200,000
Recognized weighted-average period	1 year
Award vesting period	3 years
Performance Share Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)	920,681	773,023
Granted (in dollars per share)	$ 11.79	$ 11.46
Recognized equity-based compensation	$ 2,800,000	$ 2,500,000
Unrecognized compensation expense related to awards	$ 14,600,000
Recognized weighted-average period	2 years 3 months 18 days
Performance Share Units Cash Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized equity-based compensation	$ 200,000	$ 200,000
Unrecognized compensation expense related to awards	$ 400,000
Recognized weighted-average period	1 year
Award vesting period			3 years

Equity-Based Compensation - Sto

Equity-Based Compensation - Stock Options (Details) - $ / shares	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Number of Shares
Outstanding at December 31, 2021 (in shares)	666,718
Granted (in shares)	0	0
Exercised (in shares)	(7,500)	(10,164)
Forfeited (in shares)	0
Expired (in shares)	(35,695)
Outstanding at March 31, 2022 (in shares)	623,523		666,718
Exercisable at March 31, 2022 (in shares)	623,523
Weighted Average Exercise Price
Outstanding at December 31, 2021 (in dollars per share)	$ 30.84
Granted (in dollars per share)	0
Exercised (in dollars per share)	11.08
Forfeited (in dollars per share)	0
Expired (in dollars per share)	20.06
Outstanding at March 31, 2022 (in dollars per share)	31.70		$ 30.84
Exercisable at March 31, 2022 (in dollars per share)	$ 31.70
Weighted Average Remaining Contractual Term in Years
Outstanding at December 31, 2021	2 years 3 months 18 days		2 years 4 months 24 days
Outstanding at March 31, 2022	2 years 3 months 18 days		2 years 4 months 24 days
Exercisable at March 31, 2022	2 years 3 months 18 days

Equity-Based Compensation - Res

Equity-Based Compensation - Restricted Stock and Restricted Stock Units Awards (Details) - Restricted Stock and Restricted Stock Units - $ / shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Number of Shares
Unvested, Beginning Balance (in shares)	1,144,310
Granted (in shares)	588,492	633,973
Vested (in shares)	(111,829)
Forfeited (in shares)	(1,058)
Unvested, Ending Balance (in shares)	1,619,915
Grant Date Weighted Average Fair Value
Unvested, Beginning Balance (in dollars per share)	$ 8.37
Granted (in dollars per share)	9.81
Vested (in dollars per share)	11.36
Forfeited (in dollars per share)	13.56
Unvested, Ending Balance (in dollars per share)	$ 8.68

Equity-Based Compensation - Per

Equity-Based Compensation - Performance Share Awards (Details) - Performance Share Units - $ / shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Number of Shares
Unvested, Beginning Balance (in shares)	1,914,589
Granted (in shares)	920,681	773,023
Vested (in shares)	(497,401)
Forfeited/Cancelled (in shares)	(658)
Unvested, Ending Balance (in shares)	2,337,211
Grant Date Weighted Average Fair Value
Unvested, Beginning Balance (in dollars per share)	$ 9.77
Granted (in dollars per share)	11.79	$ 11.46
Vested (in dollars per share)	14.56
Forfeited/Cancelled (in dollars per share)	13.86
Unvested, Ending Balance (in dollars per share)	$ 9.54

Commitments and Contingencies -

Commitments and Contingencies - Future Minimum Annual Commitments (Details) $ in Thousands	Mar. 31, 2022USD ($)
Minimum Purchase Commitments
2022 (remaining nine months)	$ 6,537
2023	5,976
2024	4,295
2025	2,886
2026	2,180
Thereafter	9,288
Total future purchase commitments	$ 31,162

Commitments and Contingencies_2

Commitments and Contingencies - Narrative (Details)	May 17, 2017USD ($)	Mar. 31, 2022USD ($)claim	Dec. 31, 2021USD ($)
Loss Contingencies
Purchased reserves	$ 94,400,000
Number of new claims | claim		0
Surety Bonds
Loss Contingencies
Surety bonds outstanding		$ 40,200,000
Reclamation Bonds
Loss Contingencies
Surety bonds outstanding		36,200,000
Other non-current assets
Loss Contingencies
Third party products claims liability under insurance in other long-term obligations		0	$ 0
Other long-term obligations
Loss Contingencies
Third party products claims liability under insurance in other long-term obligations		$ 900,000	$ 900,000
Pending Litigation
Loss Contingencies
Number of pending claims | claim		42

Pension and Post-Retirement B_3

Pension and Post-Retirement Benefits - Net Pension and Post-Retirement Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Pension Benefits
Pension Plans, Postretirement and Other Employee Benefits
Service cost	$ 689	$ 805
Interest cost	689	739
Expected return on plan assets	(1,418)	(1,429)
Net amortization and deferral	499	950
Net pension and post-retirement benefit costs	459	1,065
Post-retirement Benefits
Pension Plans, Postretirement and Other Employee Benefits
Service cost	6	19
Interest cost	36	102
Unrecognized prior service cost	(516)	0
Unrecognized net (gain)/loss	(34)	0
Net pension and post-retirement benefit costs	$ (508)	$ 121

Pension and Post-Retirement B_4

Pension and Post-Retirement Benefits - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2022USD ($)plan	Mar. 31, 2021USD ($)
Pension Plans, Postretirement and Other Employee Benefits
Number of multiemployer defined benefit plans | plan	3
Percentage of contributions to individual multiemployer plan (less than)	5.00%	5.00%
Company contributions to qualified pension plans	$ 1.8	$ 1.5
Certain Employees
Pension Plans, Postretirement and Other Employee Benefits
Percentage of contribution over defined benefit plan	4.00%
All Other Eligible Employees
Pension Plans, Postretirement and Other Employee Benefits
Percentage of contribution over defined benefit plan based on eligible earnings (up to)	6.00%
Pension Plans
Pension Plans, Postretirement and Other Employee Benefits
Company's contributions to qualified plans	$ 0	$ 1.3
Expected contributions to the plans for the 2021 fiscal year	0
Post-retirement Medical Plan
Pension Plans, Postretirement and Other Employee Benefits
Expected contributions to the plans for the 2021 fiscal year	$ 1.1

Leases - Narrative (Details)

Leases - Narrative (Details)	3 Months Ended
	Mar. 31, 2022
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	Mar. 31, 2022	Dec. 31, 2021
Assets
Operating	$ 37,417	$ 38,793
Finance	4,334	3,448
Total leased assets	41,751	42,241
Current
Operating	13,158	14,469
Finance	1,291	1,061
Non-current
Operating	71,355	75,130
Finance	3,160	2,485
Total lease liabilities	$ 88,964	$ 93,145
Weighted average remaining lease term:
Operating	6 years 8 months 12 days	6 years 10 months 24 days
Finance	4 years 2 months 12 days	3 years 7 months 6 days
Weighted average discount rate:
Operating	5.70%	5.70%
Finance	5.00%	5.10%
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Current portion of long-term debt	Current portion of long-term debt
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Long-term debt, net	Long-term debt, net

Leases - Components of Lease Ex

Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Lessee, Lease, Description [Line Items]
Total lease costs	$ 7,982	$ 8,665
Finance lease expense	400	45
Cost of sales
Lessee, Lease, Description [Line Items]
Operating lease costs	7,628	8,137
Short-term operating lease costs	4,700	3,700
Selling, general and administrative
Lessee, Lease, Description [Line Items]
Operating lease costs	354	528
Short-term operating lease costs	$ 100	$ 100

Leases - Supplemental Cash Flow

Leases - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows for operating leases	$ 7,518	$ 8,159
Financing cash flows for finance leases	330	45
Right-of-use assets obtained in exchange for new lease liabilities:
Operating leases	1,188	1,306
Finance leases	$ 2,102	$ 843

Leases - Maturities of Lease Li

Leases - Maturities of Lease Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Operating leases
2022 (remaining nine months)	$ 13,004
2023	20,958
2024	17,014
2025	13,347
2026	11,474
Thereafter	31,855
Total lease payments	107,652
Less: Interest	19,696
Less: Other operating expenses	3,443
Total	84,513
Finance leases
2022 (remaining nine months)	1,109
2023	1,469
2024	1,154
2025	805
2026	271
Thereafter	33
Total lease payments	4,841
Less: Interest	390
Less: Other operating expenses	0
Total	$ 4,451	$ 3,546

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended				12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2021
Income Tax Contingency [Line Items]
Refundable NOL carryback claims filed in accordance with CARES Act provisions	$ 400					$ 21,500
Income expense (benefit)	$ (6,969)	$ (4,354)
Effective tax rate	45.00%	17.00%
Effective tax rate without the effects of discrete tax items	48.00%	24.00%
Tax expense (benefit) related equity compensation	$ 300	$ 1,400
COVID-19
Income Tax Contingency [Line Items]
Income tax refunds received				$ 36,600
Refundable NOL credits under CARES Act			$ 26,300		$ 26,300
Refunds received from NOL credits under CARES Act	$ 21,100		$ 4,900
Deferred tax benefit recorded under CARES Act					$ 22,300

Revenue - Sales by Major Source

Revenue - Sales by Major Source (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Revenue [Line Items]
Total sales	$ 304,887	$ 234,416
Oil & Gas Proppants
Disaggregation of Revenue [Line Items]
Total sales	176,244	121,697
Industrial & Specialty Products
Disaggregation of Revenue [Line Items]
Total sales	128,643	112,719
Product
Disaggregation of Revenue [Line Items]
Total sales	233,234	191,390
Product | Oil & Gas Proppants
Disaggregation of Revenue [Line Items]
Total sales	104,591	78,671
Product | Industrial & Specialty Products
Disaggregation of Revenue [Line Items]
Total sales	128,643	112,719
Service
Disaggregation of Revenue [Line Items]
Total sales	71,653	43,026
Service | Oil & Gas Proppants
Disaggregation of Revenue [Line Items]
Total sales	71,653	43,026
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	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Unbilled Receivables
Beginning Balance	$ 1,957	$ 47,982
Reclassifications to billed receivables	(1,957)	(512)
Revenues recognized in excess of period billings	2,500	1,647
Ending Balance	2,500	49,117
Deferred Revenue
Beginning Balance	20,741	33,692
Revenues recognized from balances held at the beginning of the period	(1,653)	(4,256)
Revenues deferred from period collections on unfulfilled performance obligations	450	3,368
Revenues recognized from period collections	(404)	(876)
Ending Balance	$ 19,134	$ 31,928

Revenue - Remaining Performance

Revenue - Remaining Performance Obligation (Details)	Mar. 31, 2022
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining duration period of expected satisfaction of performance obligations (less than)	1 year

Revenue - Narrative (Details)

Revenue - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Jun. 30, 2021	Dec. 31, 2021
Supply Commitment [Line Items]
Revenue recognized as result of settlement dispute with a customer	$ 304,887	$ 234,416
Total assets of VIE	2,187,697			$ 2,219,600
Foreign Operations
Supply Commitment [Line Items]
Revenue recognized as result of settlement dispute with a customer	25,254	21,696
Total assets of VIE	$ 34,200	$ 27,600
Minimum Purchase Commitment Agreement | One Customer
Supply Commitment [Line Items]
Revenue recognized as result of settlement dispute with a customer			$ 49,000
Unbilled receivable related to settlement dispute with customer			43,900
Billed receivable related to dispute with customer			$ 1,100

Revenue - Foreign Operations (D

Revenue - Foreign Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Revenue [Line Items]
Total sales	$ 304,887	$ 234,416
Pre-tax income	(15,483)	(25,289)
Net income	(8,393)	(20,778)
Foreign Operations
Disaggregation of Revenue [Line Items]
Total sales	25,254	21,696
Pre-tax income	4,813	4,138
Net income	$ 3,802	$ 3,269

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Officer | Transportation Brokerage and Logistics Services Vendor
Related Party Transaction [Line Items]
Related party purchases	$ 0	$ 0

Segment Reporting - Narrative (

Segment Reporting - Narrative (Details)	3 Months Ended
	Mar. 31, 2022USD ($)segmentproduct	Dec. 31, 2021USD ($)	Dec. 31, 2020USD ($)
Segment Reporting Information
Number of reportable segments | segment	2
Number of product types (over) | product	600
Goodwill	$ 185,649,000	$ 185,649,000	$ 185,600,000
Oil & Gas Proppants
Segment Reporting Information
Goodwill	0		0
Industrial & Specialty Products
Segment Reporting Information
Goodwill	$ 185,600,000		$ 185,600,000

Segment Reporting - Sales and S

Segment Reporting - Sales and Segment Contribution Margin for Reporting Segments and Other Operating Results (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information
Total sales	$ 304,887	$ 234,416
Total segment contribution margin	82,587	61,578
Operating activities excluded from segment cost of sales	(4,569)	(4,151)
Selling, general and administrative	(40,110)	(26,224)
Depreciation, depletion and amortization	(37,749)	(41,348)
Goodwill and other asset impairments	0	(38)
Interest expense	(17,173)	(17,711)
Other income, net, including interest income	1,531	2,605
Income tax benefit	6,969	4,354
Net loss	(8,514)	(20,935)
Less: Net loss attributable to non-controlling interest	(121)	(157)
Net loss attributable to U.S. Silica Holdings, Inc.	(8,393)	(20,778)
Oil & Gas Proppants
Segment Reporting Information
Total sales	176,244	121,697
Total segment contribution margin	44,753	21,540
Industrial & Specialty Products
Segment Reporting Information
Total sales	128,643	112,719
Total segment contribution margin	$ 37,834	$ 40,038

Subsequent Events (Details)

Subsequent Events (Details) $ in Millions	Apr. 01, 2022USD ($)
Subsequent Event | Product | Oil & Gas Proppants
Subsequent Event
Capacity reservation fee	$ 20