U.S. Silica (SLCA) 10-Q 3 Aug 16 2016 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2016	Aug. 01, 2016
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q2
Entity Registrant Name	U.S. Silica Holdings, Inc.
Entity Central Index Key	1,524,741
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		63,583,321

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Current Assets:
Cash and cash equivalents	$ 454,208	$ 277,077
Short-term investments	0	21,849
Accounts receivable, net	54,293	58,706
Inventories, net	67,158	65,004
Prepaid expenses and other current assets	8,899	9,921
Income tax deposits	1,145	6,583
Total current assets	585,703	439,140
Property, plant and mine development, net	555,487	561,196
Goodwill	68,647	68,647
Trade names	14,474	14,474
Customer relationships, net	6,205	6,453
Deferred Tax Assets, Net, Noncurrent	1,314	0
Other assets	17,323	18,709
Total assets	1,249,153	1,108,619
Current Liabilities:
Accounts payable	48,217	49,631
Dividends payable	4,080	3,453
Accrued liabilities	11,538	11,708
Accrued interest	57	58
Current portion of long-term debt	3,336	3,330
Deferred revenue	4,622	15,738
Total current liabilities	71,850	83,918
Long-term debt	486,705	488,375
Deferred revenue	67,537	59,676
Liability for pension and other post-retirement benefits	63,887	55,893
Deferred income taxes, net	0	19,513
Other long-term obligations	17,828	17,077
Total liabilities	707,807	724,452
Preferred Stock, Value, Outstanding	0	0
Stockholders’ Equity:
Common stock	639	539
Additional paid-in capital	381,349	194,670
Retained earnings	190,964	220,974
Treasury stock, at cost	(10,850)	(15,845)
Accumulated other comprehensive loss	(20,756)	(16,171)
Total stockholders’ equity	541,346	384,167
Total liabilities and stockholders’ equity	$ 1,249,153	$ 1,108,619

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income Statement [Abstract]
Sales	$ 116,994	$ 147,511	$ 239,504	$ 351,469
Cost of goods sold (excluding depreciation, depletion and amortization)	102,707	117,200	209,458	255,853
Operating expenses
Selling, general and administrative	14,585	6,575	30,088	33,536
Depreciation, depletion and amortization	15,209	13,695	29,765	26,938
Total operating expenses	29,794	20,270	59,853	60,474
Operating income (loss)	(15,507)	10,041	(29,807)	35,142
Other income (expense)
Interest expense	(6,647)	(6,928)	(13,290)	(13,764)
Other income, net, including interest income	608	498	2,398	509
Total other (expenses) income	(6,039)	(6,430)	(10,892)	(13,255)
Income (loss) before income taxes	(21,546)	3,611	(40,699)	21,887
Income tax benefit	9,555	6,342	18,048	2,889
Net income (loss)	$ (11,991)	$ 9,953	$ (22,651)	$ 24,776
Earnings (loss) per share:
Basic (in usd per share)	$ (0.19)	$ 0.19	$ (0.38)	$ 0.46
Diluted (in usd per share)	$ (0.19)	$ 0.18	$ (0.38)	$ 0.46
Weighted Average Number of Shares Outstanding, Basic	63,417	53,303	58,900	53,361
Weighted Average Number of Shares Outstanding, Diluted	63,417	53,857	58,900	53,864
Common stock cash dividend declared, per share	$ 0.06	$ 0.13	$ 0.13	$ 0.25

Condensed Consolidated Stateme4

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (11,991)	$ 9,953	$ (22,651)	$ 24,776
Other comprehensive income (loss):
Unrealized gain (loss) on derivatives (net of tax of ($12) and $6 for the three months ended June 30, 2016 and 2015, respectively, and $9 and $8 for the six months ended June 30, 2016 and 2015, respectively)	(20)	9	15	12
Unrealized gain (loss) on investments (net of tax of ($1) and $8 for the three months ended June 30, 2016 and 2015, respectively, and ($4) and $30 for the six months ended June 30, 2016 and 2015, respectively)	(1)	14	(6)	49
Pension and other post-retirement benefits liability adjustment (net of tax of ($1,227) and $2,823 for the three months ended June 30, 2016 and 2015, respectively, and ($2,768) and $2,588 for the six months ended June 30, 2016 and 2015, respectively)	(2,036)	4,557	(4,594)	4,178
Comprehensive income (loss)	$ (14,048)	$ 14,533	$ (27,236)	$ 29,015

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Unrealized gain (loss) on derivatives, tax	$ (12)	$ 9	$ 9	$ 8
Unrealized gain (loss) on investments, tax	(1)	8	(4)	30
Pension and other post-retirement benefits liability adjustment, tax	$ (1,227)	$ 2,823	$ (2,768)	$ 2,588

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Stockholders' Equity - 6 months ended Jun. 30, 2016 - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-In Capital	Retained Earnings (Deficit)	Accumulated Other Comprehensive Income (Loss)
Balance at December 31, 2015 at Dec. 31, 2015	$ 384,167	$ 539	$ (15,845)	$ 194,670	$ 220,974	$ (16,171)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(22,651)				(22,651)
Stock Issued During Period, Value, New Issues	186,202	100		186,102
Unrealized gain on derivatives	15					15
Unrealized loss on short-term investments	(6)					(6)
Pension and post-retirement liability	(4,594)					(4,594)
Cash dividend declared ($0.125 per share)	(7,359)				(7,359)
Common stock-based compensation plans activity:	5,355			5,355
Adjustment to Additional Paid in Capital, Income Tax Effect from Share-based Compensation, Net	(123)			(123)
Unrealized loss on short-term investments	1,299		1,950	(651)
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	0		1,335	(1,335)
Pension and post-retirement liability	(959)	0	1,710	(2,669)
Balance at June 30, 2016 at Jun. 30, 2016	$ 541,346	$ 639	$ (10,850)	$ 381,349	$ 190,964	$ (20,756)

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Stockholders' Equity (Parenthetical) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2016$ / shares	Jun. 30, 2016USD ($)$ / shares
Statement of Stockholders' Equity [Abstract]
Price per share (in USD per share)	$ 20	$ 20
Stock issuance costs | $		$ 13,798
Common stock cash dividend declared, per share	$ 0.06	$ 0.13

Condensed Consolidated Stateme8

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Operating activities:
Net income (loss)	$ (22,651)	$ 24,776
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization	29,765	26,938
Debt issuance amortization	696	703
Original issue discount amortization	192	192
Deferred income taxes	(18,199)	(6,903)
Deferred revenue	(3,255)	(9,216)
Loss on disposal of property, plant and equipment	29	811
Equity-based compensation	5,355	(89)
Excess tax benefit from equity-based compensation	0	(264)
Bad debt provision	101	(1,231)
Other	1,211	(5,927)
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable	4,312	44,335
Inventories	(2,154)	2,529
Prepaid expenses and other current assets	1,022	(445)
Income taxes	5,438	(3,233)
Accounts payable and accrued liabilities	(1,584)	(35,446)
Accrued interest	(1)	0
Liability for pension and other post-retirement benefits	1,044	927
Net cash provided by operating activities	1,321	38,457
Investing activities:
Capital expenditures	(23,388)	(27,128)
Maturities of short-term investments	21,872	4,593
Proceeds from sale of property, plant and equipment	66	77
Net cash used in investing activities	(1,450)	(22,458)
Financing activities:
Dividends paid	(6,732)	(13,444)
Repurchase of common stock	0	(15,255)
Issuance of common stock	200,000	0
Common stock issuance costs	(13,798)
Proceeds from options exercised	1,299	363
Excess tax benefit from equity-based compensation	0	264
Tax payments related to shares withheld for vested restricted stock	(959)	(722)
Repayment of long-term debt	(2,550)	(2,550)
Financing fees	0	(64)
Net cash provided by/(used in) financing activities	177,260	(31,408)
Net increase/(decrease) in cash and cash equivalents	177,131	(15,409)
Cash and cash equivalents, beginning of period	277,077	263,066
Cash and cash equivalents, end of period	454,208	247,657
Cash paid (received) during the period for:
Interest	10,571	10,977
Taxes	$ (5,299)	$ 6,984

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2016
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	NOTE A—SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation and Consolidation The accompanying Condensed Consolidated Financial Statements (the “Financial Statements”) of U.S. Silica Holdings, Inc. (“Holdings,” and together with its subsidiaries “we,” “us” or the “Company”) 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, 2015 ; therefore, the interim Condensed Consolidated Financial Statements should be read in conjunction with that Annual Report on Form 10-K. In the opinion of management, all adjustments necessary for a fair presentation of the Financial Statements have been included. Such adjustments are of a normal, recurring nature. We have reclassified certain immaterial amounts in the prior years’ operating activities section of the consolidated statement of cash flows to conform to the current year presentation. These reclassifications had no effect on previously reported net cash flows from operations. In order to make this report easier to read, we refer throughout to (i) our Condensed Consolidated Balance Sheets as our “Balance Sheets,” (ii) our Condensed Consolidated Statements of Operations as our “Income Statements,” and (iii) our Condensed Consolidated Statements of Cash Flows as our “Cash Flows.” Unaudited Interim Financial Statements The accompanying Balance Sheet as of June 30, 2016 ; the Income Statements and Condensed Consolidated Statements of Comprehensive Income for the three and six months ended June 30, 2016 and 2015 ; the Condensed Consolidated Statements of Stockholders' Equity and Cash Flows for the six months ended June 30, 2016 ; and other information disclosed in the related notes are unaudited. The Balance Sheet as of December 31, 2015 was derived from our audited consolidated financial statements as included in our 2015 Annual Report. Use of Estimates and Assumptions The preparation of the Financial Statements requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and the related disclosure of contingent assets and liabilities at the date of the Financial Statements and the reported amounts of revenues and expenses during the reporting period. The more significant areas requiring the use of management estimates and assumptions relate to mineral reserves that are the basis for future cash flow estimates utilized in impairment calculations and units-of-production amortization calculations; environmental, reclamation and closure obligations; estimates of recoverable minerals; estimates of allowance for doubtful accounts; estimates of fair value for certain reporting units and asset impairments (including impairments of goodwill and other long-lived assets); write-downs of inventory to net realizable value; equity-based compensation expense; post-employment, post-retirement and other employee benefit liabilities; valuation allowances for deferred tax assets; reserves for contingencies and litigation; and the fair value and accounting treatment of financial instruments including derivative instruments. We base our estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances. Accordingly, actual results may differ significantly from these estimates under different assumptions or conditions. Recently Issued Accounting Pronouncements In March 2016, the Financial Accounting Standards Board ("FASB") issued an Accounting Standards Update, Improvements to Employee Share-Based Payment Accounting, which simplifies the income tax consequences, accounting for forfeitures and classification on the Statements of Cash Flows. This Update is effective for public entities for financial statements issued for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years; early application is permitted. We are currently evaluating the effect that the new guidance will have on our financial statements and related disclosures. In February 2016, the FASB issued an Accounting Standards Update, Leases, which supersedes the existing lease guidance and requires all leases with a term greater than 12 months to be recognized on the balance sheet as assets and obligations. This Update is effective for public entities for financial statements issued for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years; early application is permitted. This standard mandates a modified retrospective transition method. We are currently evaluating the effect that the new guidance will have on our financial statements and related disclosures. On July 22, 2015, the FASB issued Accounting Standards Update, Simplifying the Measurement of Inventory. The new standard requires an entity to measure most inventory at the lower of cost and net realizable value, thereby simplifying the current guidance under which an entity must measure inventory at the lower of cost or market. The new standard will not apply to inventories that are measured using either the last-in, first-out (LIFO) method or the retail inventory method. This Update is effective for public entities for financial statements issued for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years; early application is permitted. We have elected to adopt the standard early effective January 1, 2016 prospectively and have measured our inventory at the lower of cost and net realizable value on our Balance Sheet as of June 30, 2016 .

Capital Structure and Accumulat

Capital Structure and Accumulated Comprehensive Income	6 Months Ended
	Jun. 30, 2016
Equity [Abstract]
Capital Structure and Accumulated Comprehensive Income	NOTE B—CAPITAL STRUCTURE AND ACCUMULATED COMPREHENSIVE INCOME Common Stock Our Amended and Restated Certificate of Incorporation authorizes up to 500,000,000 shares of common stock, par value of $0.01 . Subject to the rights of holders of any series of preferred stock, all of the voting power of the stockholders of Holdings shall be vested in the holders of the common stock. In March 2016, we completed a public offering of 10,000,000 shares of our common stock for total cash proceeds of approximately $186.2 million net of underwriting discounts and offering costs. There were 63,581,010 shares of common stock issued and outstanding at June 30, 2016 . As of June 30, 2015 , there were 53,383,613 shares issued and outstanding. During the six months ended June 30, 2016 , our Board of Directors declared quarterly cash dividends as follows: Dividends per Common Share Declaration Date Record Date Payable Date $ 0.0625 February 22, 2016 March 15, 2016 April 5, 2016 $ 0.0625 May 5, 2016 June 15, 2016 July 6, 2016 All dividends were paid as scheduled. Any determination to pay dividends and other distributions in cash, stock, or property by Holdings in the future will be at the discretion of our Board of Directors and will be dependent on then-existing conditions, including our business conditions, our financial condition, results of operations, liquidity, capital requirements, contractual restrictions including restrictive covenants contained in our debt agreements, and other factors. Additionally, because we are a holding company, our ability to pay dividends on our common stock may be limited by restrictions on the ability of our subsidiaries to pay dividends or make distributions to us, including restrictions under the terms of the agreements governing our indebtedness. Preferred Stock Our Amended and Restated Certificate of Incorporation authorizes our Board of Directors to issue up to 10,000,000 shares, in the aggregate, of preferred stock, par value of $0.01 in one or more series, to fix the powers, preferences and other rights of such series, and any qualifications, limitations or restrictions thereof, including the dividend rate, conversion rights, voting rights, redemption rights and liquidation preference, and to fix the number of shares to be included in any such series, without any further vote or action by our stockholders. There were no shares of preferred stock issued or outstanding at either June 30, 2016 or December 31, 2015 . At present, we have no plans to issue any preferred stock. Employee Stock Awards We grant stock options, restricted stock, restricted stock units and performance share units to our employees and directors under the Amended and Restated U.S. Silica Holdings, Inc. 2011 Incentive Compensation Plan. The weighted-average stock awards (in thousands) that are antidilutive and are therefore excluded from the calculation of our diluted earnings per common share are: Three Months Ended Six Months Ended 2016 2015 2016 2015 Weighted-average outstanding stock options excluded 1,252 450 1,279 371 Weighted-average outstanding restricted stock awards excluded 1,318 897 844 798 Share Repurchase Program We are authorized by our Board of Directors to repurchase shares of our outstanding common stock from time to time on the open market or in privately negotiated transactions. As of June 30, 2016 , we are authorized to repurchase up to $50 million of our common stock through December 11, 2016. Stock repurchases, if any, will be funded using our available liquidity. The timing and amount of stock repurchases will depend on a variety of factors, including the market conditions as well as corporate and regulatory considerations. Under our share repurchase program, as of June 30, 2016 , we have repurchased 706,093 shares of our common stock at an average price of $23.83 and are authorized to repurchase up to an additional $33.2 million of our common stock. Accumulated Other Comprehensive Income Accumulated other comprehensive income (loss) consists of fair value adjustments associated with cash flow hedges and accumulated adjustments for net experience losses and prior service cost related to employee benefit plans. The following table presents the changes in accumulated other comprehensive income (in thousands) by component during the six months ended June 30, 2016 : For the Six Months Ended June 30, 2016 Unrealized gain/(loss) on cash flow hedges Unrealized gain/(loss) on short-term investments Pension and other post-retirement benefits liability Total Beginning Balance $ (81 ) $ 6 $ (16,096 ) $ (16,171 ) Other comprehensive income (loss) before reclassifications (66 ) (6 ) (4,878 ) (4,950 ) Amounts reclassed from accumulated other comprehensive income 81 — 284 365 Ending Balance $ (66 ) $ — $ (20,690 ) $ (20,756 ) Amounts reclassified from accumulated other comprehensive income (loss) related to cash flow hedges category are included in interest expense in our Income Statements and amounts reclassified related to pension and other post-retirement benefits liability category are included in the computation of net periodic pension costs, respectively, at before tax amounts.

Accounts Receivable

Accounts Receivable	6 Months Ended
	Jun. 30, 2016
Receivables [Abstract]
Accounts Receivable	NOTE C—ACCOUNTS RECEIVABLE At June 30, 2016 and December 31, 2015 , accounts receivable (in thousands) consisted of the following: June 30, December 31, Trade receivables $ 60,675 $ 64,821 Less: Allowance for doubtful accounts (7,543 ) (7,686 ) Net trade receivables 53,132 57,135 Other receivables 1,161 1,571 Total accounts receivable $ 54,293 $ 58,706 Changes in our allowance for doubtful accounts (in thousands) during the six months ended June 30, 2016 are as follows: June 30, Beginning balance $ 7,686 Bad debt provision 101 Write-offs (244 ) Ending balance $ 7,543

Inventories

Inventories	6 Months Ended
	Jun. 30, 2016
Inventory Disclosure [Abstract]
Inventories	NOTE D—INVENTORIES At June 30, 2016 and December 31, 2015 , inventories (in thousands) consisted of the following: June 30, December 31, Supplies $ 17,617 $ 18,029 Raw materials and work in process 19,655 18,113 Finished goods 29,886 28,862 Total inventories $ 67,158 $ 65,004

Property, Plant and Mine Develo

Property, Plant and Mine Development	6 Months Ended
	Jun. 30, 2016
Property, Plant and Equipment [Abstract]
Property, Plant and Mine Development	NOTE E—PROPERTY, PLANT AND MINE DEVELOPMENT At June 30, 2016 and December 31, 2015 , property, plant and mine development (in thousands) consisted of the following: June 30, December 31, Mining property and mine development $ 235,910 $ 222,439 Asset retirement cost 9,887 9,889 Land 30,322 30,322 Land improvements 37,977 37,791 Buildings 51,779 51,280 Machinery and equipment 369,316 360,817 Furniture and fixtures 1,917 1,917 Construction-in-progress 56,062 56,130 793,170 770,585 Accumulated depletion, depreciation and amortization (237,683 ) (209,389 ) Total property, plant and mine development, net $ 555,487 $ 561,196 The amount of interest costs capitalized in property, plant and mine development was $151 and $281 for the six months ended June 30, 2016 and 2015 , respectively.

Debt

Debt	6 Months Ended
	Jun. 30, 2016
Debt Disclosure [Abstract]
Debt	NOTE F—DEBT At June 30, 2016 and December 31, 2015 , debt (in thousands) consisted of the following: June 30, December 31, Senior secured credit facility: Revolver expiring July 23, 2018 (5% at June 30, 2016 and December 31, 2015) $ — $ — Term loan facility—final maturity July 23, 2020 (4% - 4.5% at June 30, 2016 and December 31, 2015) 496,725 499,275 Less: Unamortized original issue discount (1,507 ) (1,696 ) Less: Unamortized debt issuance cost (5,177 ) (5,874 ) Total debt 490,041 491,705 Less: current portion (3,336 ) (3,330 ) Total long-term portion of debt $ 486,705 $ 488,375 Revolving Line-of-Credit We have a $50 million revolving line-of-credit (the “Revolver”), with zero drawn and $3.3 million allocated for letters of credit as of June 30, 2016 , leaving $46.7 million available under the Revolver. Debt Maturities At June 30, 2016 , contractual maturities of long-term debt (in thousands) are as follows: 2016 $ 2,550 2017 5,100 2018 5,100 2019 5,100 2020 478,875 $ 496,725 Our senior secured credit facility is secured by substantially all of our assets and a pledge of the equity interests in certain of our subsidiaries. The facility contains covenants that, among other things, govern our ability to create, incur or assume indebtedness and liens, to make acquisitions or investments, to pay dividends and to sell assets. The facility also requires us to maintain a consolidated total net leverage ratio of no more than 3.75 :1.00 as of the last day of any fiscal quarter whenever usage of the Revolver (other than certain undrawn letters of credit) exceeds 25% of the Revolver commitment. As of June 30, 2016 , we are in compliance with all covenants in accordance with our senior secured credit facility.

Asset Retirement Obligations

Asset Retirement Obligations	6 Months Ended
	Jun. 30, 2016
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligations	NOTE G—ASSET RETIREMENT OBLIGATIONS Mine reclamation costs, or future remediation costs for inactive mines, are accrued based on management’s best estimate at the end of each period of the costs expected to be incurred at a site. Such cost estimates include, where applicable, ongoing care, maintenance and monitoring costs. Changes in estimates at inactive mines are reflected in earnings in the period an estimate is revised. As of June 30, 2016 , we had a liability of $12.7 million in other long-term obligations related to our asset retirement obligation. Changes in the asset retirement obligation (in thousands) during the six months ended June 30, 2016 are as follows: June 30, Beginning balance $ 12,254 Payments — Accretion 480 Additions and revisions of prior estimates — Ending balance $ 12,734

Fair Value Accounting

Fair Value Accounting	6 Months Ended
	Jun. 30, 2016
Fair Value Disclosures [Abstract]
Fair Value Accounting	NOTE H - 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 June 30, 2016 and December 31, 2015 approximate their reported carrying values. Short-Term Investments In general, the fair value of our short-term investments is based on quoted prices for similar assets in active markets, or for identical assets or similar assets in markets in which there were fewer transactions (Level 2). Money market mutual funds are based on calculated net asset value and are reported in Level 1. Variable rate demand obligations underwritten and remarketed by a financial institution are priced at par value. Long-Term Debt, Including Current Maturities We believe that the fair values of our long-term debt, including current maturities, approximate their carrying values based on their effective interest rates compared to current market rates. Derivative Instruments The estimated fair value of our derivative assets (interest rate caps) are recorded at each reporting period and are based upon widely accepted valuation techniques, including discounted cash flow analysis on the expected cash flows of each derivative contract. This analysis reflects the contractual terms of the derivatives, including the period to maturity, and uses observable market-based inputs, including interest rate curves and implied volatilities. We also incorporate credit valuation adjustments to appropriately reflect both our nonperformance risk as well as that of the respective counterparty in the fair value measurements. Although we have determined that the majority of the inputs used to value our derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with our derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default of ourselves and our counterparties. However, as of June 30, 2016 , we have assessed that the impact of the credit valuation adjustments on the overall valuation of our derivative positions is not significant. As a result, we have determined that our derivative valuations in their entirety are classified in Level 2 of the fair value hierarchy. In accordance with the fair value hierarchy, the following table presents the fair value as of June 30, 2016 of those assets that we measure at fair value on a recurring basis: Level 1 Level 2 Total Interest rate derivatives $ — $ 18 $ 18

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	NOTE I - COMMITMENTS AND CONTINGENCIES Future Minimum Annual Commitments at June 30, 2016 : Operating Leases Minimum Purchase Commitments 2016 $ 23,232 $ 14,398 2017 48,687 18,205 2018 58,549 15,596 2019 52,466 12,363 2020 48,687 4,258 Thereafter 157,427 14,850 Total future lease and purchase commitments $ 389,048 $ 79,670 Operating Leases We are obligated under certain operating leases for railroad cars, office space, mining property, mining/processing equipment and transportation and other equipment. Certain operating lease agreements include options to purchase the equipment for fair market value at the end of the original lease term. In general, the above leases include renewal options and provide that we pay for all utilities, insurance, taxes and maintenance. Expense related to operating leases and rental agreements totaled approximately $12.2 million and $11.7 million for the three months ended June 30, 2016 and 2015 , respectively, and $25.0 million and $21.7 million for the six months ended June 30, 2016 and 2015 , respectively. As of June 30, 2016 , we have no obligations under a capital lease. Minimum Purchase Commitments We enter into service agreements with our transload service providers and transportation service providers. Some of these agreements require us to purchase a minimum amount of services over a specific period of time. Any inability to meet these minimum contract requirements requires us to pay a shortfall fee, which is based on the difference between the minimum amount contracted for and the actual amount purchased. Other Commitments and Contingencies Our operating subsidiary, U.S. Silica Company (“U.S. Silica”), has been named as a defendant in various product liability claims alleging silica exposure causing silicosis. During the six months ended June 30, 2016 , no new claims were brought against U.S. Silica. As of June 30, 2016 , there were 74 active silica-related products liability claims pending in which U.S. Silica is a defendant. Although the outcomes of these claims cannot be predicted with certainty, in the opinion of management, it is not reasonably possible that the ultimate resolution of these matters will have a material adverse effect on our financial position or results of operations that exceeds the accrual amounts. We have recorded estimated liabilities for these claims in other long-term obligations as well as estimated recoveries under the indemnity agreement and an estimate of future recoveries under insurance in other assets on our consolidated balance sheets. As of both June 30, 2016 , and December 31, 2015 other non-current assets included $0.3 million for insurance for third-party products liability claims and other long-term obligations included $1.5 million in third-party products claims liability. Additionally, during the three months ended March 31, 2015, we received an unfavorable ruling in an arbitration proceeding as a result of exiting a toll manufacturing contract. The amount of the ruling was approximately $7.6 million . The matter was settled and the settlement amount of $6.5 million was paid on June 9, 2015, which was included in selling, general and administrative expense in our Income Statement for the six months ended June 30, 2015 .

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2016
Income Tax Disclosure [Abstract]
Income Taxes	NOTE J - 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. The effective tax rate was 44% and (13)% for the six months ended June 30, 2016 and 2015 , respectively. Historically, our actual effective tax rates have differed from the statutory effective rate primarily due to the benefit received from statutory percentage depletion allowances. The deduction for statutory percentage depletion does not necessarily change proportionately to changes in income before income taxes.

Pension and Post-Retirement Ben

Pension and Post-Retirement Benefits	6 Months Ended
	Jun. 30, 2016
Compensation and Retirement Disclosure [Abstract]
Pension and Post-Retirement Benefits	NOTE K - PENSION AND POST-RETIREMENT BENEFITS We maintain a single-employer noncontributory defined benefit pension plan covering certain employees. Net pension benefit cost (in thousands) recognized for the three and six months ended June 30, 2016 and 2015 are as follows: Three Months Ended Six Months Ended 2016 2015 2016 2015 Service cost $ 3 $ 324 $ 291 $ 647 Interest cost 13 1,203 1,248 2,406 Expected return on plan assets (15 ) (1,375 ) (1,407 ) (2,749 ) Net amortization and deferral 7 666 489 1,333 Net pension benefit costs $ 8 $ 818 $ 621 $ 1,637 In addition, we provide defined benefit post-retirement health care and life insurance benefits to some employees. Net periodic post-retirement benefit cost recognized for the three and six months ended June 30, 2016 and 2015 are as follows: Three Months Ended Six Months Ended 2016 2015 2016 2015 Service cost $ 44 $ 44 $ 89 $ 88 Interest cost 306 277 613 554 Expected return on plan assets — (1 ) (1 ) (2 ) Special termination benefit 21 — 21 — Net amortization and deferral 135 96 269 192 Net post-retirement costs $ 506 $ 416 $ 991 $ 832 The weighted average discount rate used to determine the projected pension and post-retirement obligations was updated during the six months ended June 30, 2016 , and was decreased from 4.5% at December 31, 2015 to 3.8% at June 30, 2016 . We made no contributions to the qualified pension plan for the three and six months ended June 30, 2016 . We contributed $1.0 million to the qualified pension plan for both the three and six months ended June 30, 2015 . Total expected employer funding contributions during the fiscal year ending December 31, 2016 are $0 for the pension plan and $1.9 million for the post-retirement medical and life plan.

Obligations under Guarantees

Obligations under Guarantees	6 Months Ended
	Jun. 30, 2016
Guarantees [Abstract]
Obligations Under Guarantees	NOTE L - OBLIGATIONS UNDER GUARANTEES We have indemnified Travelers Casualty and Surety Company of America (“Travelers”) against any loss Travelers may incur in the event that holders of surety bonds, issued on behalf of us by Travelers, execute the bonds. As of June 30, 2016 , Travelers had $10.2 million in bonds outstanding for us. The majority of these bonds, $9.9 million , relate to reclamation requirements issued by various governmental authorities. Reclamation bonds remain outstanding until the mining area is reclaimed and the authority issues a formal release. The remaining bonds relate to such indefinite purposes as licenses, permits, and tax collection.

Segment Reporting

Segment Reporting	6 Months Ended
	Jun. 30, 2016
Segment Reporting [Abstract]
Segment Reporting	NOTE M - 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 by providing fracturing sand, or “frac sand,” which is pumped down oil and natural gas wells to prop open rock fissures and increase the flow rate of oil and natural gas from the wells. The Industrial & Specialty Products segment consists of over 260 products and materials used in a variety of industries, including container glass, fiberglass, specialty glass, flat glass, building products, fillers and extenders, foundry products, chemicals, recreation products and filtration products. An operating segment’s performance is primarily evaluated based on segment contribution margin, which excludes certain corporate costs not associated with the operations of the segment. These corporate costs are separately stated below and include costs that are related to functional areas such as operations management, corporate purchasing, accounting, treasury, information technology, legal and human resources. We believe that segment contribution margin, as defined above, is an appropriate measure for evaluating the operating performance of our segments. However, this measure should be considered in addition to, not a substitute for, or superior to, net income (loss) or other measures of financial performance prepared in accordance with generally accepted accounting principles. The other accounting policies of each of the two reporting segments are the same as those in Note A - Summary of Significant Accounting Policies of our Financial Statements. The following table presents sales and segment contribution margin (in thousands) for the reporting segments and other operating results not allocated to the reported segments for the three and six months ended June 30, 2016 and 2015 : Three Months Ended Six Months Ended 2016 2015 2016 2015 Sales: Oil & Gas Proppants $ 64,926 $ 90,855 $ 138,791 $ 239,607 Industrial & Specialty Products 52,068 56,656 100,713 111,862 Total Sales 116,994 147,511 239,504 351,469 Segment contribution margin: Oil & Gas Proppants (5,995 ) 13,257 (5,144 ) 65,451 Industrial & Specialty Products 21,486 19,531 38,380 34,987 Total segment contribution margin 15,491 32,788 33,236 100,438 Operating activities excluded from segment cost of goods sold (1,204 ) (2,477 ) (3,190 ) (4,822 ) Selling, general and administrative (14,585 ) (6,575 ) (30,088 ) (33,536 ) Depreciation, depletion and amortization (15,209 ) (13,695 ) (29,765 ) (26,938 ) Interest expense (6,647 ) (6,928 ) (13,290 ) (13,764 ) Other income, net, including interest income 608 498 2,398 509 Income tax benefit 9,555 6,342 18,048 2,889 Net income (loss) $ (11,991 ) $ 9,953 $ (22,651 ) $ 24,776 Asset information, including capital expenditures and depreciation, depletion, and amortization, by segment is not included in reports used by management in its monitoring of performance and, therefore, is not reported by segment. Goodwill of $68.6 million has been allocated to these segments with $47.9 million assigned to Oil & Gas Proppants and $20.7 million to Industrial & Specialty Products.

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2016
Subsequent Events [Abstract]
Subsequent Events	NOTE N - SUBSEQUENT EVENTS On July 6, 2016 , we paid a cash dividend of $ 0.0625 per share to common stockholders of record on June 15, 2016 , which had been declared by our Board of Directors on May 5, 2016 . On July 15, 2016, we entered into an agreement and plan of merger pursuant to which we will acquire all of the outstanding capital stock of New Birmingham, Inc., a regional sand producer located near Tyler, Texas. The consideration includes 2.6 million shares of our common stock and approximately $111.1 million in cash and liabilities assumed, subject to customary adjustments at closing. The transaction is expected to close in August 2016, subject to receiving regulatory approvals. On July 21, 2016 , our Board of Directors declared a quarterly cash dividend of $0.0625 per share to common stockholders of record at the close of business on September 15, 2016 , payable on October 4, 2016 . On August 1, 2016, we entered into a purchase agreement pursuant to which we will acquire all of the outstanding membership units of Sandbox Enterprises LLC, a provider of logistics solutions and technology for the transportation of proppant used in hydraulic fracturing in the oil and gas industry. The consideration includes 4.2 million shares of our common stock and approximately $75 million in cash and liabilities assumed, subject to customary adjustments at closing. The transaction is expected to close in August 2016, subject to receiving regulatory approvals.

Summary of Significant Accoun23

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2016
Accounting Policies [Abstract]
Basis of Presentation and Consolidation	Basis of Presentation and Consolidation The accompanying Condensed Consolidated Financial Statements (the “Financial Statements”) of U.S. Silica Holdings, Inc. (“Holdings,” and together with its subsidiaries “we,” “us” or the “Company”) 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, 2015 ; therefore, the interim Condensed Consolidated Financial Statements should be read in conjunction with that Annual Report on Form 10-K. In the opinion of management, all adjustments necessary for a fair presentation of the Financial Statements have been included. Such adjustments are of a normal, recurring nature. We have reclassified certain immaterial amounts in the prior years’ operating activities section of the consolidated statement of cash flows to conform to the current year presentation. These reclassifications had no effect on previously reported net cash flows from operations. In order to make this report easier to read, we refer throughout to (i) our Condensed Consolidated Balance Sheets as our “Balance Sheets,” (ii) our Condensed Consolidated Statements of Operations as our “Income Statements,” and (iii) our Condensed Consolidated Statements of Cash Flows as our “Cash Flows.”
Unaudited Interim Financial Statements	Unaudited Interim Financial Statements The accompanying Balance Sheet as of June 30, 2016 ; the Income Statements and Condensed Consolidated Statements of Comprehensive Income for the three and six months ended June 30, 2016 and 2015 ; the Condensed Consolidated Statements of Stockholders' Equity and Cash Flows for the six months ended June 30, 2016 ; and other information disclosed in the related notes are unaudited. The Balance Sheet as of December 31, 2015 was derived from our audited consolidated financial statements as included in our 2015 Annual Report.
Use of Estimates and Assumptions	Use of Estimates and Assumptions The preparation of the Financial Statements requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and the related disclosure of contingent assets and liabilities at the date of the Financial Statements and the reported amounts of revenues and expenses during the reporting period. The more significant areas requiring the use of management estimates and assumptions relate to mineral reserves that are the basis for future cash flow estimates utilized in impairment calculations and units-of-production amortization calculations; environmental, reclamation and closure obligations; estimates of recoverable minerals; estimates of allowance for doubtful accounts; estimates of fair value for certain reporting units and asset impairments (including impairments of goodwill and other long-lived assets); write-downs of inventory to net realizable value; equity-based compensation expense; post-employment, post-retirement and other employee benefit liabilities; valuation allowances for deferred tax assets; reserves for contingencies and litigation; and the fair value and accounting treatment of financial instruments including derivative instruments. We base our estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances. Accordingly, actual results may differ significantly from these estimates under different assumptions or conditions.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In March 2016, the Financial Accounting Standards Board ("FASB") issued an Accounting Standards Update, Improvements to Employee Share-Based Payment Accounting, which simplifies the income tax consequences, accounting for forfeitures and classification on the Statements of Cash Flows. This Update is effective for public entities for financial statements issued for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years; early application is permitted. We are currently evaluating the effect that the new guidance will have on our financial statements and related disclosures. In February 2016, the FASB issued an Accounting Standards Update, Leases, which supersedes the existing lease guidance and requires all leases with a term greater than 12 months to be recognized on the balance sheet as assets and obligations. This Update is effective for public entities for financial statements issued for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years; early application is permitted. This standard mandates a modified retrospective transition method. We are currently evaluating the effect that the new guidance will have on our financial statements and related disclosures.

Capital Structure and Accumul24

Capital Structure and Accumulated Comprehensive Income (Tables)	6 Months Ended
	Jun. 30, 2016
Equity [Abstract]
Schedule of Quarterly Cash Dividends	Dividends per Common Share Declaration Date Record Date Payable Date $ 0.0625 February 22, 2016 March 15, 2016 April 5, 2016 $ 0.0625 May 5, 2016 June 15, 2016 July 6, 2016
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]	Three Months Ended Six Months Ended 2016 2015 2016 2015 Weighted-average outstanding stock options excluded 1,252 450 1,279 371 Weighted-average outstanding restricted stock awards excluded 1,318 897 844 798
Changes in Accumulated Other Comprehensive Income	The following table presents the changes in accumulated other comprehensive income (in thousands) by component during the six months ended June 30, 2016 : For the Six Months Ended June 30, 2016 Unrealized gain/(loss) on cash flow hedges Unrealized gain/(loss) on short-term investments Pension and other post-retirement benefits liability Total Beginning Balance $ (81 ) $ 6 $ (16,096 ) $ (16,171 ) Other comprehensive income (loss) before reclassifications (66 ) (6 ) (4,878 ) (4,950 ) Amounts reclassed from accumulated other comprehensive income 81 — 284 365 Ending Balance $ (66 ) $ — $ (20,690 ) $ (20,756 )

Accounts Receivable (Tables)

Accounts Receivable (Tables)	6 Months Ended
	Jun. 30, 2016
Receivables [Abstract]
Schedule of Accounts Receivable	At June 30, 2016 and December 31, 2015 , accounts receivable (in thousands) consisted of the following: June 30, December 31, Trade receivables $ 60,675 $ 64,821 Less: Allowance for doubtful accounts (7,543 ) (7,686 ) Net trade receivables 53,132 57,135 Other receivables 1,161 1,571 Total accounts receivable $ 54,293 $ 58,706 Changes in our allowance for doubtful accounts (in thousands) during the six months ended June 30, 2016 are as follows: June 30, Beginning balance $ 7,686 Bad debt provision 101 Write-offs (244 ) Ending balance $ 7,543

Inventories (Tables)

Inventories (Tables)	6 Months Ended
	Jun. 30, 2016
Inventory Disclosure [Abstract]
Schedule of Inventories	At June 30, 2016 and December 31, 2015 , inventories (in thousands) consisted of the following: June 30, December 31, Supplies $ 17,617 $ 18,029 Raw materials and work in process 19,655 18,113 Finished goods 29,886 28,862 Total inventories $ 67,158 $ 65,004

Property, Plant and Mine Deve27

Property, Plant and Mine Development (Tables)	6 Months Ended
	Jun. 30, 2016
Property, Plant and Equipment [Abstract]
Schedule of Property, Plant and Mine Development	At June 30, 2016 and December 31, 2015 , property, plant and mine development (in thousands) consisted of the following: June 30, December 31, Mining property and mine development $ 235,910 $ 222,439 Asset retirement cost 9,887 9,889 Land 30,322 30,322 Land improvements 37,977 37,791 Buildings 51,779 51,280 Machinery and equipment 369,316 360,817 Furniture and fixtures 1,917 1,917 Construction-in-progress 56,062 56,130 793,170 770,585 Accumulated depletion, depreciation and amortization (237,683 ) (209,389 ) Total property, plant and mine development, net $ 555,487 $ 561,196

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2016
Debt Disclosure [Abstract]
Schedule of Debt	At June 30, 2016 and December 31, 2015 , debt (in thousands) consisted of the following: June 30, December 31, Senior secured credit facility: Revolver expiring July 23, 2018 (5% at June 30, 2016 and December 31, 2015) $ — $ — Term loan facility—final maturity July 23, 2020 (4% - 4.5% at June 30, 2016 and December 31, 2015) 496,725 499,275 Less: Unamortized original issue discount (1,507 ) (1,696 ) Less: Unamortized debt issuance cost (5,177 ) (5,874 ) Total debt 490,041 491,705 Less: current portion (3,336 ) (3,330 ) Total long-term portion of debt $ 486,705 $ 488,375
Schedule of Contractual Maturities of Debt	At June 30, 2016 , contractual maturities of long-term debt (in thousands) are as follows: 2016 $ 2,550 2017 5,100 2018 5,100 2019 5,100 2020 478,875 $ 496,725

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	6 Months Ended
	Jun. 30, 2016
Asset Retirement Obligation Disclosure [Abstract]
Schedule of Changes in Asset Retirement Obligation	Changes in the asset retirement obligation (in thousands) during the six months ended June 30, 2016 are as follows: June 30, Beginning balance $ 12,254 Payments — Accretion 480 Additions and revisions of prior estimates — Ending balance $ 12,734

Fair Value Accounting (Tables)

Fair Value Accounting (Tables)	6 Months Ended
	Jun. 30, 2016
Fair Value Disclosures [Abstract]
Schedule of Measure at Fair Value on Recurring Basis	In accordance with the fair value hierarchy, the following table presents the fair value as of June 30, 2016 of those assets that we measure at fair value on a recurring basis: Level 1 Level 2 Total Interest rate derivatives $ — $ 18 $ 18

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Annual Commitments	Future Minimum Annual Commitments at June 30, 2016 : Operating Leases Minimum Purchase Commitments 2016 $ 23,232 $ 14,398 2017 48,687 18,205 2018 58,549 15,596 2019 52,466 12,363 2020 48,687 4,258 Thereafter 157,427 14,850 Total future lease and purchase commitments $ 389,048 $ 79,670

Pension and Post-Retirement B32

Pension and Post-Retirement Benefits (Tables)	6 Months Ended
	Jun. 30, 2016
Compensation and Retirement Disclosure [Abstract]
Summarizes Information about Pension and Post-Retirement Benefit Plans	We maintain a single-employer noncontributory defined benefit pension plan covering certain employees. Net pension benefit cost (in thousands) recognized for the three and six months ended June 30, 2016 and 2015 are as follows: Three Months Ended Six Months Ended 2016 2015 2016 2015 Service cost $ 3 $ 324 $ 291 $ 647 Interest cost 13 1,203 1,248 2,406 Expected return on plan assets (15 ) (1,375 ) (1,407 ) (2,749 ) Net amortization and deferral 7 666 489 1,333 Net pension benefit costs $ 8 $ 818 $ 621 $ 1,637 In addition, we provide defined benefit post-retirement health care and life insurance benefits to some employees. Net periodic post-retirement benefit cost recognized for the three and six months ended June 30, 2016 and 2015 are as follows: Three Months Ended Six Months Ended 2016 2015 2016 2015 Service cost $ 44 $ 44 $ 89 $ 88 Interest cost 306 277 613 554 Expected return on plan assets — (1 ) (1 ) (2 ) Special termination benefit 21 — 21 — Net amortization and deferral 135 96 269 192 Net post-retirement costs $ 506 $ 416 $ 991 $ 832

Segment Reporting (Tables)

Segment Reporting (Tables)	6 Months Ended
	Jun. 30, 2016
Segment Reporting [Abstract]
Presentation of Sales and Segment Contribution Margin for Reporting Segments and Other Operating Results	The following table presents sales and segment contribution margin (in thousands) for the reporting segments and other operating results not allocated to the reported segments for the three and six months ended June 30, 2016 and 2015 : Three Months Ended Six Months Ended 2016 2015 2016 2015 Sales: Oil & Gas Proppants $ 64,926 $ 90,855 $ 138,791 $ 239,607 Industrial & Specialty Products 52,068 56,656 100,713 111,862 Total Sales 116,994 147,511 239,504 351,469 Segment contribution margin: Oil & Gas Proppants (5,995 ) 13,257 (5,144 ) 65,451 Industrial & Specialty Products 21,486 19,531 38,380 34,987 Total segment contribution margin 15,491 32,788 33,236 100,438 Operating activities excluded from segment cost of goods sold (1,204 ) (2,477 ) (3,190 ) (4,822 ) Selling, general and administrative (14,585 ) (6,575 ) (30,088 ) (33,536 ) Depreciation, depletion and amortization (15,209 ) (13,695 ) (29,765 ) (26,938 ) Interest expense (6,647 ) (6,928 ) (13,290 ) (13,764 ) Other income, net, including interest income 608 498 2,398 509 Income tax benefit 9,555 6,342 18,048 2,889 Net income (loss) $ (11,991 ) $ 9,953 $ (22,651 ) $ 24,776

Earnings Per Share - Schedule o

Earnings Per Share - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Employee Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average outstanding stock options excluded	1,252	450
Employee Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average outstanding stock options excluded			1,279	371
Restricted Stock and Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average outstanding stock options excluded	1,318	897	844	798

Capital Structure and Accumul35

Capital Structure and Accumulated Comprehensive Income (Detail) - USD ($)	6 Months Ended
	Jun. 30, 2016	Mar. 22, 2016	Jun. 30, 2015
Capital Structure And Accumulated Comprehensive Income (Loss)
Common stock issued (shares)	63,581,010		53,383,613
Common stock outstanding (shares)	63,581,010		53,383,613
Preferred stock issued (shares)	0		0
Preferred stock outstanding (shares)	0		0
Authorization to repurchase common stock	$ 50,000,000
Repurchase of common stock (shares)	706,093
Average price per common share of repurchase common stock (in USD per share)	$ 23.83
Remaining authorized repurchase of common stock amount	$ 33,200,000
SecondaryOfferingShares		10,000,000
Common Stock
Capital Structure And Accumulated Comprehensive Income (Loss)
Common stock authorized (shares)	500,000,000
Common stock, par value	$ 0.01
Preferred Stock
Capital Structure And Accumulated Comprehensive Income (Loss)
Preferred stock authorized (shares)	10,000,000
Preferred stock, par value	$ 0.01

Capital Structure and Accumul36

Capital Structure and Accumulated Comprehensive Income - Schedule of Quarterly Cash Dividends (Details) - $ / shares	3 Months Ended
	Jun. 30, 2016	Mar. 31, 2015
Equity [Abstract]
Dividends, Common Stock, Cash	$ 0.0625
Declaration date	May 5, 2016	Feb. 22, 2016
Record date	Jun. 15, 2016	Mar. 15, 2016
Payable date	Jul. 6, 2016	Apr. 5, 2016

Capital Structure and Accumul37

Capital Structure and Accumulated Comprehensive Income - Changes in Accumulated Other Comprehensive Income (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2016USD ($)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	$ (16,171)
Other comprehensive income (loss) before reclassifications	(4,950)
Amounts reclassed from accumulated other comprehensive income	365
Ending Balance	(20,756)
Unrealized Gains and Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(81)
Other comprehensive income (loss) before reclassifications	(66)
Amounts reclassed from accumulated other comprehensive income	81
Ending Balance	(66)
Unrealized Gain/(Loss) on Short-Term Investments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	6
Other comprehensive income (loss) before reclassifications	(6)
Amounts reclassed from accumulated other comprehensive income	0
Ending Balance	0
Pension and Other Postretirement Benefits Liability
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(16,096)
Other comprehensive income (loss) before reclassifications	(4,878)
Amounts reclassed from accumulated other comprehensive income	284
Ending Balance	$ (20,690)

Business Combination (Details)

Business Combination (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Business Acquisition
Goodwill	$ 68,647	$ 68,647

Business Combination - Schedule

Business Combination - Schedule of Purchase Price Allocation (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Business Acquisition
Goodwill	$ 68,647	$ 68,647

Accounts Receivable - Schedule

Accounts Receivable - Schedule of Accounts Receivable (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Receivables [Abstract]
Trade receivables	$ 60,675	$ 64,821
Less: Allowance for doubtful accounts	(7,543)	(7,686)
Net trade receivables	53,132	57,135
Other receivables	1,161	1,571
Total accounts receivable	$ 54,293	$ 58,706

Accounts Receivable - Allowance

Accounts Receivable - Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Allowance for Doubtful Accounts Receivable
Beginning balance	$ 7,686
Bad debt provision	101	$ (1,231)
Write-offs	(244)
Ending balance	$ 7,543

Inventories - Schedule of Inven

Inventories - Schedule of Inventories (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Inventory Disclosure [Abstract]
Supplies	$ 17,617	$ 18,029
Raw materials and work in process	19,655	18,113
Finished goods	29,886	28,862
Total inventories	$ 67,158	$ 65,004

Property, Plant and Mine Deve43

Property, Plant and Mine Development (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Property, Plant and Equipment
Interest Costs Capitalized	$ 151	$ 281

Property, Plant and Mine Deve44

Property, Plant and Mine Development - Schedule of Property, Plant and Mine Development (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Property, Plant and Equipment
Interest Costs Capitalized	$ 151	$ 281
Property, plant and mine development	793,170		$ 770,585
Accumulated depletion, depreciation and amortization	(237,683)		(209,389)
Total property, plant and mine development, net	555,487		561,196
Mining Property and Mine Development
Property, Plant and Equipment
Property, plant and mine development	235,910		222,439
Asset Retirement Cost
Property, Plant and Equipment
Property, plant and mine development	9,887		9,889
Land
Property, Plant and Equipment
Property, plant and mine development	30,322		30,322
Land Improvements
Property, Plant and Equipment
Property, plant and mine development	37,977		37,791
Buildings
Property, Plant and Equipment
Property, plant and mine development	51,779		51,280
Machinery and Equipment
Property, Plant and Equipment
Property, plant and mine development	369,316		360,817
Furniture and Fixtures
Property, Plant and Equipment
Property, plant and mine development	1,917		1,917
Construction-in-Progress
Property, Plant and Equipment
Property, plant and mine development	$ 56,062		$ 56,130

Debt (Detail)

Debt (Detail)	6 Months Ended
	Jun. 30, 2016USD ($)
Short-term Debt
Credit facility consolidated total net leverage ratio	0.0375
Net leverage ratio, credit facility threshold (percentage)	25.00%
Revolving Line-of-Credit
Short-term Debt
Available borrowing base	$ 50,000,000
Amount drawn from borrowing base	0
Amount available for general corporate use under this revolving credit agreement	46,700,000
Letter of Credit
Short-term Debt
Amount allocated for letters of credit	$ 3,300,000

Debt - Schedule of Debt (Detail

Debt - Schedule of Debt (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Line of Credit Facility
Less: Unamortized debt issuance cost	$ (5,177)	$ (5,874)
Total debt	490,041	491,705
Less: current portion	(3,336)	(3,330)
Total long-term portion of debt	486,705	488,375
Revolving Line-of-Credit
Line of Credit Facility
Total debt	$ 0	$ 0
Credit facility, maturity date	Jul. 23, 2018
Credit facility, interest rate	5.00%	5.00%
Term Loan Facility
Line of Credit Facility
Less: Unamortized original issue discount	$ (1,507)	$ (1,696)
Total debt	$ 496,725	$ 499,275
Credit facility, maturity date	Jul. 23, 2020
Minimum | Term Loan Facility
Line of Credit Facility
Credit facility, interest rate	4.00%	4.00%
Maximum | Term Loan Facility
Line of Credit Facility
Credit facility, interest rate	4.50%	4.50%

Debt - Schedule of Contractual

Debt - Schedule of Contractual Maturities of Debt (Detail) $ in Thousands	Jun. 30, 2016USD ($)
Debt Disclosure [Abstract]
2,015	$ 2,550
2,017	5,100
2,018	5,100
2,019	5,100
2,020	478,875
Total debt	$ 496,725

Asset Retirement Obligations (D

Asset Retirement Obligations (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligation	$ 12,734	$ 12,254

Asset Retirement Obligations -

Asset Retirement Obligations - Schedule of Changes in Asset Retirement Obligation (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2016USD ($)
Asset Retirement Obligation Disclosure [Abstract]
Beginning balance	$ 12,254
Payments	0
Accretion	480
Additions and revisions of prior estimates	0
Ending balance	$ 12,734

Fair Value Accounting - Schedul

Fair Value Accounting - Schedule of Measure at Fair Value on Recurring Basis (Detail) - Measured at Fair Value on Recurring Basis $ in Thousands	Jun. 30, 2016USD ($)
Defined Benefit Plan Disclosure
Interest rate derivatives	$ 18
Level 1
Defined Benefit Plan Disclosure
Interest rate derivatives	0
Level 2
Defined Benefit Plan Disclosure
Interest rate derivatives	$ 18

Short-Term Investments - Schedu

Short-Term Investments - Schedule of Available-for-Sale Short-Term Investments (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities
Fair Value	$ 0	$ 21,849

Commitments and Contingencies52

Commitments and Contingencies (Detail) $ in Thousands	Jun. 09, 2015USD ($)	Jun. 30, 2016USD ($)claim	Jun. 30, 2015USD ($)	Jun. 30, 2016USD ($)claim	Jun. 30, 2015USD ($)	Dec. 31, 2015USD ($)
Insurance [Abstract]
Expenses related to operating leases and rental agreements		$ 12,200	$ 11,700	$ 25,000	$ 21,700
New claims filed | claim				0
Third party products claims liability under insurance in other assets		311		$ 311		$ 300
Third party products claims liability under insurance in other long-term obligations		$ 1,500		$ 1,500		$ 1,500
Selling, General and Administrative Expense
Loss Contingencies
Litigation settlement expense					$ 7,600
Payments for Legal Settlements	$ 6,500
Pending Litigation
Loss Contingencies
Number of pending claims | claim		74		74

Commitments and Contingencies -

Commitments and Contingencies - Schedule of Future Minimum Annual Commitments (Details) $ in Thousands	Jun. 30, 2016USD ($)
Operating Leases
2,015	$ 23,232
2,016	48,687
2,017	58,549
2,018	52,466
2,019	48,687
Thereafter	157,427
Total future lease commitments	389,048
Minimum Purchase Commitments
2,015	14,398
2,016	18,205
2,017	15,596
2,018	12,363
2,019	4,258
Thereafter	14,850
Total future purchase commitments	$ 79,670

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Loss Contingencies
Effective income tax rate	44.00%	(13.00%)
Selling, General and Administrative Expense
Loss Contingencies
Litigation settlement expense		$ 7.6

Pension and Post-Retirement B55

Pension and Post-Retirement Benefits (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Pension Benefits
Defined Benefit Plan Disclosure
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	3.80%		3.80%		4.50%
Contributions to plan by employer	$ 0	$ 1,000	$ 0	$ 1,000
Expected contributions in current fiscal year			0
Post-retirement Benefits
Defined Benefit Plan Disclosure
Expected contributions in current fiscal year			$ 1,900

Pension and Post-Retirement B56

Pension and Post-Retirement Benefits - Summarizes Information about Pension and Post-Retirement Benefit Plans (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Pension Benefits
Defined Benefit Plan Disclosure
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	3.80%		3.80%		4.50%
Service cost	$ 3	$ 324	$ 291	$ 647
Interest cost	13	1,203	1,248	2,406
Expected return on plan assets	(15)	(1,375)	(1,407)	(2,749)
Net amortization and deferral	7	666	489	1,333
Net pension benefit costs	8	818	621	1,637
Post-retirement Benefits
Defined Benefit Plan Disclosure
Service cost	44	44	89	88
Interest cost	306	277	613	554
Expected return on plan assets	0	(1)	(1)	(2)
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments	(21)	0	(21)	0
Net amortization and deferral	135	96	269	192
Net pension benefit costs	$ 506	$ 416	$ 991	$ 832

Obligations Under Guarantees (D

Obligations Under Guarantees (Detail) - Travelers Casualty and Surety Company $ in Millions	Jun. 30, 2016USD ($)
Surety Bonds
Loss Contingencies
Surety bonds outstanding	$ 10.2
Reclamation Bonds
Loss Contingencies
Bonds related to reclamation requirements	$ 9.9

Segment Reporting (Detail)

Segment Reporting (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2016USD ($)SegmentProduct	Dec. 31, 2015USD ($)
Segment Reporting Information
Number of reportable segments | Segment	2
Number of products in Industrial & Specialty segment (over 260) | Product	260
Goodwill	$ 68,647	$ 68,647
Industrial & Specialty Products segment description	Over 260 products and materials used in a variety of industries including, container glass, fiberglass, specialty glass, flat glass, building products, fillers and extenders, foundry products, chemicals, recreation products and filtration products.
Oil & Gas Proppants
Segment Reporting Information
Goodwill	$ 47,900
Industrial & Specialty Products
Segment Reporting Information
Goodwill	$ 20,700

Segment Reporting - Presentatio

Segment Reporting - Presentation of Sales and Segment Contribution Margin for Reporting Segments and Other Operating Results (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting Information
Total Sales	$ 116,994	$ 147,511	$ 239,504	$ 351,469
Total segment contribution margin	15,491	32,788	33,236	100,438
Operating activities excluded from segment cost of goods sold	(1,204)	(2,477)	(3,190)	(4,822)
Selling, general and administrative	(14,585)	(6,575)	(30,088)	(33,536)
Depreciation, depletion and amortization	(15,209)	(13,695)	(29,765)	(26,938)
Interest expense	(6,647)	(6,928)	(13,290)	(13,764)
Other income, net, including interest income	608	498	2,398	509
Income Tax Expense (Benefit)	(9,555)	(6,342)	(18,048)	(2,889)
Net income (loss)	(11,991)	9,953	(22,651)	24,776
Operating Segments | Oil & Gas Proppants
Segment Reporting Information
Total Sales	64,926	90,855	138,791	239,607
Total segment contribution margin	(5,995)	13,257	(5,144)	65,451
Operating Segments | Industrial & Specialty Products
Segment Reporting Information
Total Sales	52,068	56,656	100,713	111,862
Total segment contribution margin	$ 21,486	$ 19,531	$ 38,380	$ 34,987

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	Oct. 04, 2016	Sep. 15, 2016	Aug. 01, 2016	Jul. 27, 2016	Jul. 15, 2016	Jun. 30, 2016	Mar. 31, 2015	Sep. 30, 2016
Subsequent Event
Payable date						Jul. 6, 2016	Apr. 5, 2016
Dividends, Common Stock, Cash						$ 0.0625
Record date						Jun. 15, 2016	Mar. 15, 2016
Declaration date						May 5, 2016	Feb. 22, 2016
Subsequent Event
Subsequent Event
Payable date	Oct. 4, 2016
Dividends, Common Stock, Cash								$ 0.0625
Record date		Sep. 15, 2016
Declaration date				Jul. 21, 2016
Subsequent Event | New Birmingham, Inc [Member]
Subsequent Event
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares					2.6
Purchase price for business acquisition					$ 111.1
Subsequent Event | New Birmingham, Inc
Subsequent Event
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares			4.2
Purchase price for business acquisition			$ 75

Uncategorized Items - slca-2016

Label	Element	Value
Stock Issued During Period, Value, New Issues	us-gaap_StockIssuedDuringPeriodValueNewIssues	$ 186,202,000