U.S. Silica (SLCA) 10-Q 30 Apr 14 2014 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2014	Apr. 28, 2014
Document And Entity Information [Abstract]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	31-Mar-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q1	'
Entity Registrant Name	'U.S. Silica Holdings, Inc.	'
Entity Central Index Key	'0001524741	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	53,758,092

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current Assets:	'	'
Cash and cash equivalents	$85,700	$78,256
Short-term investments	75,068	74,980
Accounts receivable, net	97,369	75,207
Inventories, net	51,171	64,212
Prepaid expenses and other current assets	13,890	11,104
Deferred income taxes, net	18,022	17,737
Total current assets	341,220	321,496
Property, plant and mine development, net	443,406	442,116
Debt issuance costs, net	5,035	5,255
Goodwill	68,403	68,403
Trade names	10,436	10,436
Customer relationships, net	6,018	6,120
Other assets	8,659	9,635
Total assets	883,177	863,461
Current Liabilities:	'	'
Book overdraft	2,529	4,659
Accounts payable	46,431	37,376
Dividends payable	26	6,709
Accrued liabilities	10,879	10,823
Accrued interest	41	41
Current portion of long-term debt	3,489	3,488
Income tax payable	2,648	1,037
Total current liabilities	66,043	64,133
Long-term debt	367,090	367,963
Liability for pension and other post-retirement benefits	36,189	36,802
Deferred income taxes, net	72,762	71,318
Other long-term obligations	14,445	13,951
Total liabilities	556,529	554,167
Stockholders' Equity:	'	'
Common stock	536	534
Preferred stock	'	'
Additional paid-in capital	180,340	174,799
Retained earnings	149,630	137,978
Treasury stock, at cost	'	'
Accumulated other comprehensive loss	-3,858	-4,017
Total stockholders' equity	326,648	309,294
Total liabilities and stockholders' equity	$883,177	$863,461

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Income Statement [Abstract]	'	'
Sales	$180,095	$122,311
Cost of goods sold (excluding depreciation, depletion and amortization)	126,770	74,412
Operating expenses	'	'
Selling, general and administrative	15,445	12,404
Depreciation, depletion and amortization	9,589	8,278
Total operating expenses	25,034	20,682
Operating income	28,291	27,217
Other (expense) income	'	'
Interest expense	-3,808	-3,576
Other income, net, including interest income	38	122
Total other (expenses) income	-3,770	-3,454
Income before income taxes	24,521	23,763
Income tax expense	-6,150	-6,486
Net income	$18,371	$17,277
Earnings per share:	'	'
Basic	$0.34	$0.33
Diluted	$0.34	$0.32

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Statement Of Income And Comprehensive Income [Abstract]	'	'
Net income	$18,371	$17,277
Other comprehensive income:	'	'
Unrealized gain (loss) on derivatives (net of tax of $(12) and $52 for the three months ended March 31, 2014 and 2013, respectively)	-19	81
Unrealized gain (loss) on investments (net of tax of $19 and $0 for the three months ended March 31, 2014 and 2013, respectively)	29	'
Pension and other post-retirement benefits liability adjustment (net of tax of $95 and $218 for the three months ended March 31, 2014 and 2013, respectively)	149	341
Comprehensive income	$18,530	$17,699

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Comprehensive Income (Parenthetical) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Statement Of Income And Comprehensive Income [Abstract]	'	'
Tax expenses on unrealized gain (loss) on derivatives	($12)	$52
Tax expense (benefit) on unrealized gain (loss) on investments	19	0
Tax expenses on pension and other post-retirement benefits liability adjustment	$95	$218

Condensed_Consolidated_Stateme3

Condensed Consolidated Statements of Stockholders' Equity (USD $)	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings (Deficit) [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
In Thousands
Beginning balance at Dec. 31, 2013	$309,294	$534	'	$174,799	$137,978	($4,017)
Net income	18,371	'	'	'	18,371	'
Other comprehensive income, net of tax	159	'	'	'	'	159
Proceeds from options exercised	3,004	2	229	2,773	'	'
Shares withheld for employee taxes related to vested restricted stock	-229	'	-229	'	'	'
Cash dividends declared ($0.125 per share of common stock)	-6,719	'	'	'	-6,719	'
Equity-based compensation	1,330	'	'	1,330	'	'
Excess tax benefit from equity-based compensation	1,438	'	'	1,438	'	'
Ending balance at Mar. 31, 2014	$326,648	$536	'	$180,340	$149,630	($3,858)

Condensed_Consolidated_Stateme4

Condensed Consolidated Statements of Stockholders' Equity (Parenthetical) (USD $)	3 Months Ended
	Mar. 31, 2014
Common stock cash dividend declared, per share	$0.13
Retained Earnings (Deficit) [Member]	'
Common stock cash dividend declared, per share	$0.13

Condensed_Consolidated_Stateme5

Condensed Consolidated Statements of Cash Flows (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Operating activities:	'	'
Net income	$18,371	$17,277
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation, depletion and amortization	9,589	8,278
Debt issuance amortization	220	131
Original issue discount amortization	66	42
Deferred income taxes	1,160	1,029
Deferred revenue	'	-1,917
Equity-based compensation	1,330	678
Excess tax benefit from equity-based compensation	-1,438	-96
Other	1,730	-880
Changes in assets and liabilities:	'	'
Accounts receivable	-22,985	-5,688
Inventories	13,041	-2,941
Prepaid expenses and other current assets	-2,786	-948
Income taxes	3,049	-14,351
Accounts payable and accrued liabilities	9,111	-6,427
Accrued interest	'	152
Liability for pension and other post-retirement benefits	-151	749
Net cash provided by (used in) operating activities	30,307	-4,912
Investing activities:	'	'
Capital expenditures	-10,606	-22,707
Net cash used in investing activities	-10,606	-22,707
Financing activities:	'	'
Dividends paid	-13,402	'
Proceeds from options exercised	3,004	788
Excess tax benefit from equity-based compensation	1,438	96
Tax payments related to shares withheld for vested restricted stock	-229	'
Repayment of long-term debt	-938	-650
Change in book overdraft	-2,130	-1,014
Change in revolving credit facility	'	10,551
Principal payments on capital lease obligations	'	-255
Net cash provided by (used in) financing activities	-12,257	9,516
Net increase (decrease) in cash and cash equivalents	7,444	-18,103
Cash and cash equivalents, beginning of period	78,256	61,022
Cash and cash equivalents, end of period	85,700	42,919
Non-cash financing activities:	'	'
Capital lease obligations incurred to acquire assets	'	744
Cash paid during the period for:	'	'
Interest	3,824	3,196
Taxes	$2,043	$20,076

Summary_of_Significant_Account

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2014
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, 2013; 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’ consolidated statement of cash flows within operating activities 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 Consolidated Balance Sheets as our “Balance Sheets,” (ii) our Consolidated Statements of Operations as our “Income Statements,” and (iii) our Consolidated Statements of Cash Flows as our “Cash Flows.”
	Unaudited Interim Financial Statements
	The accompanying Balance Sheet as of March 31, 2014, the Income Statements for the three months ended March 31, 2014 and 2013; the Consolidated Statements of Comprehensive Income for the three months ended March 31, 2014 and 2013; the Consolidated Statements of Cash Flows for the three months ended March 31, 2014 and 2013; and other information disclosed in the related notes are unaudited. The Balance Sheet as of December 31, 2013 was derived from our audited consolidated financial statements as included in our 2013 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 Adopted Accounting Pronouncements
	No recently adopted or new accounting pronouncements have had, or are expected to have, a material effect on our financial position, results of operations, or cash flows during the three months ended March 31, 2014.

Earnings_Per_Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2014
Earnings Per Share [Abstract]	'
Earnings Per Share	'
	NOTE B—EARNINGS PER SHARE
	Basic income 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 income per common share is computed similarly to basic income 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. In accordance with the applicable accounting guidance for calculating earnings per share, we did not include in our calculation of diluted earnings per share for the applicable periods stock options where the exercise prices were greater than the average market prices. We did not have significant stock options that were antidilutive for the three months ended March 31, 2014 and 2013, respectively.
		Three Months Ended
		March 31,
		2014			2013
	Net income	$	18,371		$	17,277
	Less: net income allocated to outstanding restricted stockholders		(42	)		(26	)
	Net income allocated to common stockholders	$	18,329		$	17,251
	Weighted-average common stock
	Outstanding		53,505			52,866
	Outstanding assuming dilution		54,054			53,131

Capital_Structure_and_Accumula

Capital Structure and Accumulated Comprehensive Income	3 Months Ended
	Mar. 31, 2014
Equity [Abstract]	'
Capital Structure and Accumulated Comprehensive Income	'
	NOTE C—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. There were 53,733,092 shares of common stock issued and outstanding at March 31, 2014. As of March 31, 2013, there were 52,987,227 shares issued and outstanding. On February 6, 2014, our Board of Directors declared a quarterly cash dividend of $0.125 per share to common stockholders of record at the close of business on March 14, 2014. The dividend payment was made to our transfer agent on March 31, 2014, and was paid to shareholders on April 1, 2014 by our transfer agent.
	Management and our Board of Directors remain committed to evaluating additional ways of creating shareholder value. 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 and to fix the preferences, powers and relative, participating, optional or other special rights and 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 are no shares of preferred stock issued or outstanding at March 31, 2014 and 2013. At present, we have no plans to issue any preferred stock.
	Share Repurchase Program
	On June 11, 2012, our Board of Directors authorized us to repurchase up to $25.0 million of our common stock. The authorization was initially for a period of 18 months, concluding on December 11, 2013, but on November 4, 2013, our Board of Directors extended the repurchase program through December 11, 2014. We are authorized to repurchase, from time to time, shares of our outstanding common stock on the open market or in privately negotiated transactions. Stock repurchases 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. The share repurchase program may be suspended, modified or discontinued at any time and we have no obligation to repurchase any additional amount of our common stock under the program. We intend to make all repurchases in compliance with applicable regulatory guidelines and to administer the plan in accordance with applicable laws, including Rule 10b-18 of the Securities Exchange Act of 1934, as amended. As part of the program, as of March 31, 2014, we have repurchased 100,000 shares of our common stock at an average price of $10.72 and are authorized to repurchase up to an additional $23.9 million of our common stock. As of March 31, 2014, all of the 100,000 shares repurchased to date have been re-issued to satisfy employee option exercises.
	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 by component during the three months ended March 31, 2014:
			For the Three Months Ended March 31, 2014
			Unrealized			Unrealized			Pension and			Total
			gain/(loss)  on			gain/(loss)  on			other
			cash flow hedges			short-term			post-retirement
						investments			benefits liability
	Beginning Balance		$	(79	)	$	(27	)	$	(3,911	)	$	(4,017	)
	Other comprehensive income (loss) before reclassifications			(21	)		29			—			8
	Amounts reclassed from accumulated other comprehensive income			2			—			149			151
	Ending Balance		$	(98	)	$	2		$	(3,762	)	$	(3,858	)
	The following table presents the reclassifications out of accumulated other comprehensive income (loss) during the three months ended March 31, 2014:
	Details about accumulated other comprehensive income		Amount reclassified from			Affected line item in the
			accumulated other			statement of operations
			comprehensive income
	Gains and losses on cash flow hedges
	Interest rate contracts		$	3		Interest expense
				(1	)	Tax expense
			$	2		Net of tax
	Amortization of postretirement benefits liability
	Actuarial gains/(losses)		$	203		-1
	Prior service cost			41		-1
			$	244		Total before tax
				(95	)	Tax expense
				149		Net of tax
	Total reclassifications for the period		$	151		Net of tax
	(1)	These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see Note M—Pension and Post-Retirement Benefits).

Accounts_Receivable

Accounts Receivable	3 Months Ended
	Mar. 31, 2014
Receivables [Abstract]	'
Accounts Receivable	'
	NOTE D—ACCOUNTS RECEIVABLE
	At March 31, 2014 and December 31, 2013, accounts receivable consisted of the following:
		March 31,			December 31,
		2014			2013
	Trade receivables	$	99,871		$	76,223
	Less: Allowance for doubtful accounts		(3,199	)		(2,376	)
	Net trade receivables		96,672			73,847
	Other receivables		697			1,360
	Total accounts receivable	$	97,369		$	75,207
	The increase of $23.6 million in trade receivables is mainly driven by the sales increase for the three months ended March 31, 2014.

Inventories

Inventories	3 Months Ended
	Mar. 31, 2014
Inventory Disclosure [Abstract]	'
Inventories	'
	NOTE E—INVENTORIES
	At March 31, 2014 and December 31, 2013, inventories consisted of the following:
		March 31,		December 31,
		2014		2013
	Supplies	$	15,936	$	15,576
	Raw materials and work in process		8,133		11,728
	Finished goods		27,102		36,908
	Total inventories	$	51,171	$	64,212
	Inventories include raw stockpiles and silica and other industrial sand available for shipment, as well as spare parts and supplies for routine facilities maintenance. We value inventory at the lower of cost or market. Cost is determined using the first-in, first-out and average cost methods. Finished goods decreased $9,806 to $27,102 as of March 31, 2014 compared to $36,908 as of December 31, 2013, primarily due to a decrease of inventory held at transloads.

Property_Plant_and_Mine_Develo

Property, Plant and Mine Development	3 Months Ended
	Mar. 31, 2014
Property Plant And Equipment [Abstract]	'
Property, Plant and Mine Development	'
	NOTE F—PROPERTY, PLANT AND MINE DEVELOPMENT
	At March 31, 2014 and December 31, 2013, property, plant and mine development consisted of the following:
		March 31,			December 31,
		2014			2013
	Mining property and mine development	$	164,609		$	164,609
	Asset retirement cost		7,275			7,275
	Land		25,738			25,738
	Land improvements		31,068			31,093
	Buildings		36,448			36,311
	Machinery and equipment		264,728			263,304
	Furniture and fixtures		1,331			1,131
	Construction-in-progress		34,849			25,974
			566,046			555,435
	Accumulated depletion, depreciation and amortization		(122,640	)		(113,319	)
	Total property, plant and mine development, net	$	443,406		$	442,116
	Depreciation expense, including depletion and amortization, recognized during the three months ended March 31, 2014 and 2013 was $9.6 million and $8.3 million, respectively. The amount of interest costs capitalized in property, plant and equipment was $201 and $128 for the three months ended March 31, 2014 and 2013, respectively. As of March 31, 2014, we hold no assets under a capital lease obligation.

Debt

Debt	3 Months Ended
	Mar. 31, 2014
Debt Disclosure [Abstract]	'
Debt	'
	NOTE G—DEBT
	At March 31, 2014 and December 31, 2013, debt consisted of the following:
		March 31,			December 31,
		2014			2013
	Senior secured credit facility:
	Revolver expiring July 23, 2018 (4.75% at March 31, 2014 and	$	—		$	—
	December 31, 2013)
	Term loan facility—final maturity July 23, 2020 (4% at March 31, 2014 and December 31, 2013), net of unamortized original issue discount of $1,609 and $1,674, respectively		370,579			371,451
	Total debt		370,579			371,451
	Less: current portion		(3,489	)		(3,488	)
	Total long-term portion of debt	$	367,090		$	367,963
	Revolving Line-of-Credit
	We have a $50 million revolving line-of-credit (the “Revolver”), with zero drawn and $3.5 million allocated for letters of credit as of March 31, 2014, leaving $46.5 million available under Revolver.
	Debt Maturities
	At March 31, 2014, contractual maturities of long-term debt are as follows:
	2014	$	2,616
	2015		3,491
	2016		3,493
	2017		3,495
	2018		3,498
	Thereafter		353,986
		$	370,579
	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 March 31, 2014, we are in compliance with all covenants in accordance with our senior secured credit facility.

Asset_Retirement_Obligations

Asset Retirement Obligations	3 Months Ended
	Mar. 31, 2014
Asset Retirement Obligation Disclosure [Abstract]	'
Asset Retirement Obligations	'
	NOTE H—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 March 31, 2014 and December 31, 2013, we had recorded a liability of $9.5 million and $9.4 million in other long-term obligations related to our asset retirement obligation. Changes in the asset retirement obligation during the three months ended March 31, 2014 and the year ended December 31, 2013, respectively, are as follows:
		March 31,		December 31,
		2014		2013
	Beginning balance	$	9,378	$	6,659
	Payments		—		—
	Accretion		168		456
	Revisions of prior estimates		—		2,263
	Ending balance	$	9,546	$	9,378

Fair_Value_Accounting

Fair Value Accounting	3 Months Ended
	Mar. 31, 2014
Fair Value Disclosures [Abstract]	'
Fair Value Accounting	'
	NOTE I—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, quote 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, 2014 and December 31, 2013 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, approximates their carrying values and 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 with Level 2 of the fair value hierarchy, the credit valuation adjustments associated with our derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default of ourselves and our counterparties. However, as of March 31, 2014, 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 March 31, 2014 of those assets that we measure at fair value on a recurring basis:
		Level 1		Level 2		Total
	Short-term investments	$	386	$	74,682	$	75,068
	Interest rate derivatives		—		74		74
	Net asset	$	386	$	74,756	$	75,142

ShortTerm_Investments

Short-Term Investments	3 Months Ended
	Mar. 31, 2014
Investments Debt And Equity Securities [Abstract]	'
Short-Term Investments	'
	NOTE J—SHORT-TERM INVESTMENTS
	We have segregated funds into designated accounts with investment brokers who manage our short-term investment portfolio. Those funds are held on an available-for-sale basis and are therefore reported at fair value on the balance sheet.
	The following table summarizes our available-for-sale short-term investments as of March 31, 2014:
		Aggregate		Gross		Gross			Fair
		Cost		Unrealized		Unrealized			Value
				Gains		Losses
	Money market mutual funds	$	386	$	—	$	—		$	386
	Fixed income securities:
	Certificates of deposit		25,230		—		(20	)		25,210
	Commercial paper		14,181		12		—			14,193
	Corporate notes and bonds		10,989		—		(7	)		10,982
	Government agencies		13,987		21		—			14,008
	U.S. Treasuries		4,810		—		(1	)		4,809
	Variable Rate Demand Obligations		5,480		—		—			5,480
	Total available-for-sale investments	$	75,063	$	33	$	(28	)	$	75,068
	As of March 31, 2014, we considered the declines in market value of our short-term investment portfolio to be temporary in nature and did not consider any of our investments other-than-temporarily impaired. We typically invest in highly-rated securities, and our investment policy generally limits the amount of credit exposure to any one issuer. The policy requires investments generally to be investment grade, with the primary objective of minimizing the potential risk of principal loss. Fair values were determined for each individual security in the investment portfolio. When evaluating an investment for other-than-temporary impairment, we review factors such as the length of time and extent to which fair value has been below its cost basis, the financial condition of the issuer and any changes thereto, changes in market interest rates, and our intent to sell, or whether it is more likely than not it will be required to sell, the investment before recovery of the investment’s cost basis. As of March 31, 2014 and December 31, 2013, we did not recognize any impairment charges.

Leases

Leases	3 Months Ended
	Mar. 31, 2014
Leases [Abstract]	'
Leases	'
	NOTE K—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. Future minimum annual commitments under such operating leases at March 31, 2014 are as follows:
	2014	$	27,731
	2015		26,780
	2016		24,555
	2017		22,319
	2018		20,910
	Thereafter		47,422
	Total future lease commitments	$	169,717
	Expense related to operating leases and rental agreements was $7.1 million and $3.3 million for the three months ended March 31, 2014 and 2013, respectively. The increase was mainly due to new leases for railroad cars.
	As of March 31, 2014, we have no obligation under a capital lease. We had an obligation under capital lease of $489 as of March 31, 2013, which was paid in full by December 31, 2013.
	In general, the above leases include renewal options and some provide that we pay for all utilities, insurance, taxes and maintenance.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2014
Commitments And Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	NOTE L—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, 2014, no new claims were brought against U.S. Silica. As of March 31, 2014, there were 88 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, the ultimate resolution of these matters will not have a material adverse effect on our financial position or results of operations.
	For periods prior to 1986, U.S. Silica had insurance policies and an indemnity from a former owner that covered silicosis claims. In the fourth quarter of 2012, U.S. Silica settled all rights under the indemnity and its underlying insurance. The settlement was received during first quarter of 2013. As a result of the settlement, the indemnity and related policies are no longer available to U.S. Silica and U.S. Silica will not seek reimbursement for any defense costs or claim payments. Other insurance policies, however, continue to remain available to U.S. Silica.
	We have recorded estimated liabilities for these claims in other long-term obligations as well as estimated recoveries under the remaining insurance policies in other assets on our consolidated balance sheets. As of March 31, 2014 and December 31, 2013, other noncurrent assets included $313 for insurance for third-party products liability claims and other long-term obligations included $1.6 million in third-party products claims liability.

Pension_and_PostRetirement_Ben

Pension and Post-Retirement Benefits	3 Months Ended
	Mar. 31, 2014
Compensation And Retirement Disclosure [Abstract]	'
Pension and Post-Retirement Benefits	'
	NOTE M—PENSION AND POST-RETIREMENT BENEFITS
	We maintain a single-employer noncontributory defined benefit pension plan covering certain employees. Net pension benefit cost recognized for the three months ended March 31, 2014 and 2013 are as follows:
		Three Months Ended
		March  31,
		2014			2013
	Service cost	$	269		$	320
	Interest cost		1,143			1,049
	Expected return on plan assets		(1,255	)		(1,265	)
	Net amortization and deferral		238			476
	Net pension benefit costs	$	395		$	580
	In addition, we provide defined benefit post-retirement healthcare and life insurance benefits to some employees. Net periodic post-retirement benefit cost recognized for the three months ended March 31, 2014 and 2013 are as follows:
		Three Months Ended
		March  31,
		2014			2013
	Service cost	$	45		$	58
	Interest cost		257			253
	Expected return on plan assets		(1	)		(1	)
	Net amortization and deferral		—			74
	Net post-retirement costs	$	301		$	384
	We contributed $0.8 million and $0 to the qualified pension plan during the three months ended March 31, 2014 and 2013, respectively. Total expected employer funding contributions during the fiscal year ending December 31, 2014 are $4.6 million for the pension plan and $1.2 million for the post-retirement medical and life plan.

Obligations_under_Guarantees

Obligations under Guarantees	3 Months Ended
	Mar. 31, 2014
Guarantees [Abstract]	'
Obligations under Guarantees	'
	NOTE N—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 March 31, 2014, Travelers had $8.2 million in bonds outstanding for us. The majority of these bonds ($8.1 million) relate to reclamation requirements issued by various governmental authorities. Reclamation bonds remain outstanding until the mining area is reclaimed and the authority issues a formal release. The remaining bonds relate to such indefinite purposes as licenses, permits, and tax collection.
	U.S. Silica is the contingent guarantor of Kanawha Rail Corporation’s (“KRC”) obligations as lessee of 199 covered hopper railroad cars, which are used by U.S. Silica to ship sand to its customers. KRC’s obligation as lessee includes paying monthly rent of $66 until June 30, 2015, maintaining the cars, paying for any cars damaged or destroyed, and indemnifying all other parties to the lease transaction against liabilities including any loss of certain tax benefits. By separate agreement between U.S. Silica and KRC, KRC may, upon the occurrence of certain events, assign the lease obligations to U.S. Silica, but none of these events have occurred.

Segment_Reporting

Segment Reporting	3 Months Ended
	Mar. 31, 2014
Segment Reporting [Abstract]	'
Segment Reporting	'
	NOTE O—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.
	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, income from operations 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 the summary of significant accounting policies.
	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 250 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.
	The following table presents sales and segment contribution margin for the reporting segments and other operating results not allocated to the reported segments for the three months ended March 31, 2014 and 2013:
		Three Months Ended
		March 31,
		2014			2013
	Sales:
	Oil & Gas Proppants	$	130,584		$	73,582
	Industrial & Specialty Products		49,511			48,729
	Total sales		180,095			122,311
	Segment contribution margin:
	Oil & Gas Proppants		41,628			36,162
	Industrial & Specialty Products		13,187			13,246
	Total segment contribution margin		54,815			49,408
	Operating activities excluded from segment cost of goods sold		(1,490	)		(1,509	)
	Selling, general and administrative		(15,445	)		(12,404	)
	Depreciation, depletion and amortization		(9,589	)		(8,278	)
	Interest expense		(3,808	)		(3,576	)
	Other income, net, including interest income		38			122
	Income (loss) before income taxes	$	24,521		$	23,763
	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 $68.4 million has been allocated to these segments with $47.7 million assigned to Oil & Gas Proppants and $20.7 million to Industrial & Specialty Products.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2014
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, 2013; 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’ consolidated statement of cash flows within operating activities 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 Consolidated Balance Sheets as our “Balance Sheets,” (ii) our Consolidated Statements of Operations as our “Income Statements,” and (iii) our Consolidated Statements of Cash Flows as our “Cash Flows.”
Unaudited Interim Financial Statements	'
	Unaudited Interim Financial Statements
	The accompanying Balance Sheet as of March 31, 2014, the Income Statements for the three months ended March 31, 2014 and 2013; the Consolidated Statements of Comprehensive Income for the three months ended March 31, 2014 and 2013; the Consolidated Statements of Cash Flows for the three months ended March 31, 2014 and 2013; and other information disclosed in the related notes, are unaudited. The Balance Sheet as of December 31, 2013 was derived from our audited consolidated financial statements as included in our 2013 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 Adopted Accounting Pronouncements	'
	Recently Adopted Accounting Pronouncements
	No recently adopted or new accounting pronouncements have had, or are expected to have, a material effect on our financial position, results of operations, or cash flows during the three months ended March 31, 2014.

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2014
Earnings Per Share [Abstract]	'
Schedule of Basic and Diluted Earnings Per Share	'
	Three Months Ended
	March 31,
		2014			2013
	Net income	$	18,371		$	17,277
	Less: net income allocated to outstanding restricted stockholders		(42	)		(26	)
	Net income allocated to common stockholders	$	18,329		$	17,251
	Weighted-average common stock
	Outstanding		53,505			52,866
	Outstanding assuming dilution		54,054			53,131

Capital_Structure_and_Accumula1

Capital Structure and Accumulated Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2014
Equity [Abstract]	'
Changes in Accumulated Other Comprehensive Income	'
	The following table presents the changes in accumulated other comprehensive income by component during the three months ended March 31, 2014:
			For the Three Months Ended March 31, 2014
			Unrealized			Unrealized			Pension and			Total
			gain/(loss) on			gain/(loss) on			other post-
			cash flow			short-term			retirement
			hedges			investments			benefits liability
	Beginning Balance		$	(79	)	$	(27	)	$	(3,911	)	$	(4,017	)
	Other comprehensive income (loss) before reclassifications			(21	)		29			—			8
	Amounts reclassed from accumulated other comprehensive income			2			—			149			151
	Ending Balance		$	(98	)	$	2		$	(3,762	)	$	(3,858	)
Reclassifications Out of Accumulated Other Comprehensive Income (Loss)	'
	The following table presents the reclassifications out of accumulated other comprehensive income (loss) during the three months ended March 31, 2014:
	Details about accumulated other comprehensive income		Amount reclassified from			Affected line item in the
			accumulated other			statement of operations
			comprehensive income
	Gains and losses on cash flow hedges
	Interest rate contracts		$	3		Interest expense
				(1	)	Tax expense
			$	2		Net of tax
	Amortization of postretirement benefits liability
	Actuarial gains/(losses)		$	203		-1
	Prior service cost			41		-1
			$	244		Total before tax
				(95	)	Tax expense
				149		Net of tax
	Total reclassifications for the period		$	151		Net of tax
	(1)	These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see Note M—Pension and Post-Retirement Benefits).

Accounts_Receivable_Tables

Accounts Receivable (Tables)	3 Months Ended
	Mar. 31, 2014
Receivables [Abstract]	'
Schedule of Accounts Receivable	'
	At March 31, 2014 and December 31, 2013, accounts receivable consisted of the following:
		March 31,			December 31,
		2014			2013
	Trade receivables	$	99,871		$	76,223
	Less: Allowance for doubtful accounts		(3,199	)		(2,376	)
	Net trade receivables		96,672			73,847
	Other receivables		697			1,360
	Total accounts receivable	$	97,369		$	75,207

Inventories_Tables

Inventories (Tables)	3 Months Ended
	Mar. 31, 2014
Inventory Disclosure [Abstract]	'
Schedule of Inventories	'
	At March 31, 2014 and December 31, 2013, inventories consisted of the following:
		March 31,		December 31,
		2014		2013
	Supplies	$	15,936	$	15,576
	Raw materials and work in process		8,133		11,728
	Finished goods		27,102		36,908
	Total inventories	$	51,171	$	64,212

Property_Plant_and_Mine_Develo1

Property, Plant and Mine Development (Tables)	3 Months Ended
	Mar. 31, 2014
Property Plant And Equipment [Abstract]	'
Schedule of Property, Plant and Mine Development	'
	At March 31, 2014 and December 31, 2013, property, plant and mine development consisted of the following:
		March 31,			December 31,
		2014			2013
	Mining property and mine development	$	164,609		$	164,609
	Asset retirement cost		7,275			7,275
	Land		25,738			25,738
	Land improvements		31,068			31,093
	Buildings		36,448			36,311
	Machinery and equipment		264,728			263,304
	Furniture and fixtures		1,331			1,131
	Construction-in-progress		34,849			25,974
			566,046			555,435
	Accumulated depletion, depreciation and amortization		(122,640	)		(113,319	)
	Total property, plant and mine development, net	$	443,406		$	442,116

Debt_Tables

Debt (Tables)	3 Months Ended
	Mar. 31, 2014
Debt Disclosure [Abstract]	'
Schedule of Debt	'
	At March 31, 2014 and December 31, 2013, debt consisted of the following:
		March 31,			December 31,
		2014			2013
	Senior secured credit facility:
	Revolver expiring July 23, 2018 (4.75% at March 31, 2014 and December 31, 2013)	$	—		$	—
	Term loan facility—final maturity July 23, 2020 (4% at March 31, 2014 and December 31, 2013), net of unamortized original issue discount of $1,609 and $1,674, respectively		370,579			371,451
	Total debt		370,579			371,451
	Less: current portion		(3,489	)		(3,488	)
	Total long-term portion of debt	$	367,090		$	367,963
Schedule of Contractual Maturities of Debt	'
	At March 31, 2014, contractual maturities of long-term debt are as follows:
	2014	$	2,616
	2015		3,491
	2016		3,493
	2017		3,495
	2018		3,498
	Thereafter		353,986
		$	370,579

Asset_Retirement_Obligations_T

Asset Retirement Obligations (Tables)	3 Months Ended
	Mar. 31, 2014
Asset Retirement Obligation Disclosure [Abstract]	'
Schedule of Changes in Asset Retirement Obligation	'
	Changes in the asset retirement obligation during the three months ended March 31, 2014 and the year ended December 31, 2013, respectively, are as follows:
		March 31,		December 31,
		2014		2013
	Beginning balance	$	9,378	$	6,659
	Payments		—		—
	Accretion		168		456
	Revisions of prior estimates		—		2,263
	Ending balance	$	9,546	$	9,378

Fair_Value_Accounting_Tables

Fair Value Accounting (Tables)	3 Months Ended
	Mar. 31, 2014
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 March 31, 2014 of those assets that we measure at fair value on a recurring basis:
		Level 1		Level 2		Total
	Short-term investments	$	386	$	74,682	$	75,068
	Interest rate derivatives		—		74		74
	Net asset	$	386	$	74,756	$	75,142

ShortTerm_Investments_Tables

Short-Term Investments (Tables)	3 Months Ended
	Mar. 31, 2014
Investments Debt And Equity Securities [Abstract]	'
Summary of Available-for-Sale Short-Term Investments	'
	The following table summarizes our available-for-sale short-term investments as of March 31, 2014:
		Aggregate		Gross		Gross			Fair
		Cost		Unrealized		Unrealized			Value
				Gains		Losses
	Money market mutual funds	$	386	$	—	$	—		$	386
	Fixed income securities:
	Certificates of deposit		25,230		—		(20	)		25,210
	Commercial paper		14,181		12		—			14,193
	Corporate notes and bonds		10,989		—		(7	)		10,982
	Government agencies		13,987		21		—			14,008
	U.S. Treasuries		4,810		—		(1	)		4,809
	Variable Rate Demand Obligations		5,480		—		—			5,480
	Total available-for-sale investments	$	75,063	$	33	$	(28	)	$	75,068

Leases_Tables

Leases (Tables)	3 Months Ended
	Mar. 31, 2014
Leases [Abstract]	'
Future Minimum Annual Commitments under Operating Leases	'
	Future minimum annual commitments under such operating leases at March 31, 2014 are as follows:
	2014	$	27,731
	2015		26,780
	2016		24,555
	2017		22,319
	2018		20,910
	Thereafter		47,422
	Total future lease commitments	$	169,717

Pension_and_PostRetirement_Ben1

Pension and Post-Retirement Benefits (Tables)	3 Months Ended
	Mar. 31, 2014
Compensation And Retirement Disclosure [Abstract]	'
Summarizes Information about Pension and Post-Retirement Benefit Plans	'
	Net pension benefit cost recognized for the three months ended March 31, 2014 and 2013 are as follows:
		Three Months Ended
		March  31,
		2014			2013
	Service cost	$	269		$	320
	Interest cost		1,143			1,049
	Expected return on plan assets		(1,255	)		(1,265	)
	Net amortization and deferral		238			476
	Net pension benefit costs	$	395		$	580
	In addition, we provide defined benefit post-retirement healthcare and life insurance benefits to some employees. Net periodic post-retirement benefit cost recognized for the three months ended March 31, 2014 and 2013 are as follows:
		Three Months Ended
		March  31,
		2014			2013
	Service cost	$	45		$	58
	Interest cost		257			253
	Expected return on plan assets		(1	)		(1	)
	Net amortization and deferral		—			74
	Net post-retirement costs	$	301		$	384

Segment_Reporting_Tables

Segment Reporting (Tables)	3 Months Ended
	Mar. 31, 2014
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 for the reporting segments and other operating results not allocated to the reported segments for the three months ended March 31, 2014 and 2013:
		Three Months Ended
		March 31,
		2014			2013
	Sales:
	Oil & Gas Proppants	$	130,584		$	73,582
	Industrial & Specialty Products		49,511			48,729
	Total sales		180,095			122,311
	Segment contribution margin:
	Oil & Gas Proppants		41,628			36,162
	Industrial & Specialty Products		13,187			13,246
	Total segment contribution margin		54,815			49,408
	Operating activities excluded from segment cost of goods sold		(1,490	)		(1,509	)
	Selling, general and administrative		(15,445	)		(12,404	)
	Depreciation, depletion and amortization		(9,589	)		(8,278	)
	Interest expense		(3,808	)		(3,576	)
	Other income, net, including interest income		38			122
	Income (loss) before income taxes	$	24,521		$	23,763

Earnings_Per_Share_Schedule_of

Earnings Per Share - Schedule of Basic and Diluted Earnings Per Share (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Earnings Per Share [Abstract]	'	'
Net income	$18,371	$17,277
Less: net income allocated to outstanding restricted stockholders	-42	-26
Net income allocated to common stockholders	$18,329	$17,251
Outstanding	53,505	52,866
Outstanding assuming dilution	54,054	53,131

Capital_Structure_and_Accumula2

Capital Structure and Accumulated Comprehensive Income - Additional Information (Detail) (USD $)	3 Months Ended			0 Months Ended	1 Months Ended	3 Months Ended
In Millions, except Share data, unless otherwise specified	Mar. 31, 2014	Feb. 06, 2014	Mar. 31, 2013	Jun. 11, 2012	Mar. 31, 2014	Mar. 31, 2014
				Common Stock [Member]	Common Stock [Member]	Common Stock [Member]
Capital Structure And Accumulated Comprehensive Income (Loss) [Line Items]	'	'	'	'	'	'
Common stock authorized, shares	500,000,000	'	'	'	'	'
Common stock, par value	$0.01	'	'	'	'	'
Common stock issued	53,733,092	'	52,987,227	'	'	'
Common stock, shares outstanding	53,733,092	'	52,987,227	'	'	'
Quarterly cash dividend declared	'	$0.13	'	'	'	'
Dividend declared date	6-Feb-14	'	'	'	'	'
Dividend declared, record date	14-Mar-14	'	'	'	'	'
Dividend declared, payable date	1-Apr-14	'	'	'	'	'
Preferred stock, shares authorized	10,000,000	'	'	'	'	'
Preferred stock, par value	$0.01	'	'	'	'	'
Preferred stock issued	0	'	0	'	'	'
Preferred stock, shares outstanding	0	'	0	'	'	'
Authorization to repurchase common stock	'	'	'	$25	'	'
Common stock repurchase authorization period	'	'	'	'	'	'18 months
Common stock repurchase authorization period, conclusion date	'	'	'	'	11-Dec-14	11-Dec-14
Number of repurchased shares, common stock	'	'	'	'	100,000	'
Repurchased common stock, average price	'	'	'	'	$10.72	'
Remaining authorized repurchase of common stock amount	'	'	'	'	$23.90	'
Re-issued shares to satisfy employee option exercises	'	'	'	'	'	100,000

Capital_Structure_and_Accumula3

Capital Structure and Accumulated Comprehensive Income - Changes in Accumulated Other Comprehensive Income (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]	'
Beginning Balance	($4,017)
Other comprehensive income (loss) before reclassifications	8
Amounts reclassed from accumulated other comprehensive income	151
Ending Balance	-3,858
Unrealized Gains and Losses on Cash Flow Hedges [Member]	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'
Beginning Balance	-79
Other comprehensive income (loss) before reclassifications	-21
Amounts reclassed from accumulated other comprehensive income	2
Ending Balance	-98
Unrealized Gain/(Loss) on Short-Term Investments [Member]	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'
Beginning Balance	-27
Other comprehensive income (loss) before reclassifications	29
Ending Balance	2
Pension and Other Postretirement Benefits Liability [Member]	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'
Beginning Balance	-3,911
Amounts reclassed from accumulated other comprehensive income	149
Ending Balance	($3,762)

Capital_Structure_and_Accumula4

Capital Structure and Accumulated Comprehensive Income - Reclassifications Out of Accumulated Other Comprehensive Income (Loss) (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'
Tax expense	($6,150)	($6,486)
Amount Reclassified from Accumulated Other Comprehensive Income [Member]	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'
Net of tax	151	'
Amount Reclassified from Accumulated Other Comprehensive Income [Member] | Unrealized Gains and Losses on Cash Flow Hedges [Member]	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'
Tax expense	-1	'
Net of tax	2	'
Amount Reclassified from Accumulated Other Comprehensive Income [Member] | Pension and Other Postretirement Benefits Liability [Member]	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'
Actuarial gains/(losses)	203	'
Prior service cost	41	'
Total before tax	244	'
Tax expense	-95	'
Net of tax	149	'
Amount Reclassified from Accumulated Other Comprehensive Income [Member] | Interest Rate Contract [Member] | Unrealized Gains and Losses on Cash Flow Hedges [Member]	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'
Interest expense	$3	'

Accounts_Receivable_Schedule_o

Accounts Receivable - Schedule of Accounts Receivable (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Receivables [Abstract]	'	'
Trade receivables	$99,871	$76,223
Less: Allowance for doubtful accounts	-3,199	-2,376
Net trade receivables	96,672	73,847
Other receivables	697	1,360
Total accounts receivable	$97,369	$75,207

Accounts_Receivable_Additional

Accounts Receivable - Additional Information (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014
Segment Reporting [Abstract]	'
Net trade receivables	$23.60

Inventories_Schedule_of_Invent

Inventories - Schedule of Inventories (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Inventory Disclosure [Abstract]	'	'
Supplies	$15,936	$15,576
Raw materials and work in process	8,133	11,728
Finished goods	27,102	36,908
Total inventories	$51,171	$64,212

Inventories_Additional_Informa

Inventories - Additional Information (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Inventory Disclosure [Abstract]	'	'
Decreased in finished goods	$9,806	'
Finished goods	$27,102	$36,908

Property_Plant_and_Mine_Develo2

Property, Plant and Mine Development - Schedule of Property, Plant and Mine Development (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Property, Plant and Equipment [Line Items]	'	'
Property, plant and mine development	$566,046	$555,435
Accumulated depletion, depreciation and amortization	-122,640	-113,319
Total property, plant and mine development, net	443,406	442,116
Mining Property and Mine Development [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, plant and mine development	164,609	164,609
Asset Retirement Cost [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, plant and mine development	7,275	7,275
Land [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, plant and mine development	25,738	25,738
Land Improvements [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, plant and mine development	31,068	31,093
Buildings [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, plant and mine development	36,448	36,311
Machinery and Equipment [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, plant and mine development	264,728	263,304
Furniture and Fixtures [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, plant and mine development	1,331	1,131
Construction-in-Progress [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, plant and mine development	$34,849	$25,974

Property_Plant_and_Mine_Develo3

Property, Plant and Mine Development - Additional Information (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Property Plant And Equipment [Abstract]	'	'
Depreciation expense, including depletion and amortization	$9,589	$8,278
Interest costs capitalized in property, plant and equipment	201	128
Capital lease obligation	$0	'

Debt_Schedule_of_Debt_Detail

Debt - Schedule of Debt (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Line of Credit Facility [Line Items]	'	'
Total debt	$370,579	$371,451
Less: current portion	-3,489	-3,488
Total long-term portion of debt	367,090	367,963
Revolving Line-of-Credit [Member]	'	'
Line of Credit Facility [Line Items]	'	'
Line of credit available	'	'
Senior Secured Credit Facility [Member]	'	'
Line of Credit Facility [Line Items]	'	'
Line of credit available	$370,579	$371,451

Debt_Schedule_of_Debt_Parenthe

Debt - Schedule of Debt (Parenthetical) (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Revolving Line-of-Credit [Member]	'	'
Line of Credit Facility [Line Items]	'	'
Credit facility, maturity date	23-Jul-18	'
Credit facility, interest rate	4.75%	4.75%
Senior Secured Credit Facility [Member]	'	'
Line of Credit Facility [Line Items]	'	'
Credit facility, maturity date	23-Jul-20	'
Credit facility, interest rate	4.00%	4.00%
Term loan facility unamortized original issue discount	1,609	1,674

Debt_Additional_Information_De

Debt - Additional Information (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014
	Ratio
Short-term Debt [Line Items]	'
Facility consolidated total net leverage ratio	3.75
Increase of commitment	25.00%
Revolving Line-of-Credit [Member]	'
Short-term Debt [Line Items]	'
Available borrowing base	50
Amount drawn from borrowing base	0
Amount allocated for letters of credit	3.5
Amount available for general corporate use under this revolving credit agreement	46.5

Debt_Schedule_of_Contractual_M

Debt - Schedule of Contractual Maturities of Debt (Detail) (USD $)	Mar. 31, 2014
In Thousands, unless otherwise specified
Debt Disclosure [Abstract]	'
2014	$2,616
2015	3,491
2016	3,493
2017	3,495
2018	3,498
Thereafter	353,986
Debt, Total	$370,579

Asset_Retirement_Obligations_A

Asset Retirement Obligations - Additional Information (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Asset Retirement Obligation Disclosure [Abstract]	'	'
Asset retirement obligation	$9.50	$9.40

Asset_Retirement_Obligations_S

Asset Retirement Obligations - Schedule of Changes in Asset Retirement Obligation (Detail) (USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Asset Retirement Obligation Disclosure [Abstract]	'	'
Beginning balance	$9,378	$6,659
Payments	'	'
Accretion	168	456
Revisions of prior estimates	'	2,263
Ending balance	$9,546	$9,378

Fair_Value_Accounting_Schedule

Fair Value Accounting - Schedule of Measure at Fair Value on Recurring Basis (Detail) (Measured at Fair Value on Recurring Basis [Member], USD $)	Mar. 31, 2014
In Thousands, unless otherwise specified
Defined Benefit Plan Disclosure [Line Items]	'
Short-term investments	$75,068
Interest rate derivatives	74
Net asset	75,142
Level 1 [Member]	'
Defined Benefit Plan Disclosure [Line Items]	'
Short-term investments	386
Net asset	386
Level 2 [Member]	'
Defined Benefit Plan Disclosure [Line Items]	'
Short-term investments	74,682
Interest rate derivatives	74
Net asset	$74,756

ShortTerm_Investments_Schedule

Short-Term Investments - Schedule of Available-for-Sale Short-Term Investments (Detail) (USD $)	Mar. 31, 2014
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'
Aggregate Cost	$75,063
Gross Unrealized Gains	33
Gross Unrealized Losses	-28
Fair Value	75,068
Money Market Mutual Funds [Member]	'
Schedule of Available-for-sale Securities [Line Items]	'
Aggregate Cost	386
Fair Value	386
Certificates of Deposit [Member]	'
Schedule of Available-for-sale Securities [Line Items]	'
Aggregate Cost	25,230
Gross Unrealized Losses	-20
Fair Value	25,210
Commercial Paper [Member]	'
Schedule of Available-for-sale Securities [Line Items]	'
Aggregate Cost	14,181
Gross Unrealized Gains	12
Fair Value	14,193
Corporate Notes and Bonds [Member]	'
Schedule of Available-for-sale Securities [Line Items]	'
Aggregate Cost	10,989
Gross Unrealized Losses	-7
Fair Value	10,982
Government Agencies [Member]	'
Schedule of Available-for-sale Securities [Line Items]	'
Aggregate Cost	13,987
Gross Unrealized Gains	21
Fair Value	14,008
U.S. Treasuries [Member]	'
Schedule of Available-for-sale Securities [Line Items]	'
Aggregate Cost	4,810
Gross Unrealized Losses	-1
Fair Value	4,809
Variable Rate Demand Obligations [Member]	'
Schedule of Available-for-sale Securities [Line Items]	'
Aggregate Cost	5,480
Fair Value	$5,480

ShortTerm_Investments_Addition

Short-Term Investments - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Amortized Cost And Fair Value Debt Securities [Abstract]	'	'
Impairment charges	$0	$0

Leases_Future_Minimum_Annual_C

Leases - Future Minimum Annual Commitments under Operating Leases (Detail) (USD $)	Mar. 31, 2014
In Thousands, unless otherwise specified
Leases [Abstract]	'
2014	$27,731
2015	26,780
2016	24,555
2017	22,319
2018	20,910
Thereafter	47,422
Total future lease commitments	$169,717

Leases_Additional_Information_

Leases - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Leases [Abstract]	'	'
Expense related to operating leases and rental agreements	$7,100,000	$3,300,000
Capital lease obligation	$0	$489,000

Commitments_and_Contingencies_

Commitments and Contingencies - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
	Claim
Insurance [Abstract]	'	'
New claims filed	0	'
Products liability claims outstanding	88	'
Third-party products claims liability under insurance in other assets	$313,000	$313,000
Third-party products claims liability under insurance in other long-term obligations	$1,600,000	$1,600,000

Pension_and_PostRetirement_Ben2

Pension and Post-Retirement Benefits - Summarizes Information about Pension and Post-Retirement Benefit Plans (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Pension Benefits [Member]	'	'
Pension Plans, Postretirement and Other Employee Benefits [Line Items]	'	'
Service cost	$269	$320
Interest cost	1,143	1,049
Expected return on plan assets	-1,255	-1,265
Net amortization and deferral	238	476
Net pension benefit costs	395	580
Post-retirement Benefits [Member]	'	'
Pension Plans, Postretirement and Other Employee Benefits [Line Items]	'	'
Service cost	45	58
Interest cost	257	253
Expected return on plan assets	-1	-1
Net amortization and deferral	'	74
Net pension benefit costs	$301	$384

Pension_and_PostRetirement_Ben3

Pension and Post-Retirement Benefits - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2014
	Pension Benefits [Member]	Pension Benefits [Member]	Scenario, Forecast [Member]	Scenario, Forecast [Member]
			Pension Benefits [Member]	Post-retirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'
Contributions to qualified pension plan	$0.80	$0	'	'
Employer contributions for the post-retirement medical and life plan	'	'	$4.60	$1.20

Obligations_Under_Guarantees_A

Obligations Under Guarantees - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014
	Vehicle
Surety Bonds [Member]	'
Loss Contingencies [Line Items]	'
Surety bonds outstanding	$8,200,000
Reclamation Bonds [Member]	'
Loss Contingencies [Line Items]	'
Bonds related to reclamation requirements	8,100,000
Kanawha Rail Corporation's [Member]	'
Loss Contingencies [Line Items]	'
Number of railroad cars	199
Payment of monthly rent	$66,000

Segment_Reporting_Additional_I

Segment Reporting - Additional Information (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
	Product
	Segment
Segment Reporting Information [Line Items]	'	'
Number of reportable segments	2	'
Number of products in Industrial & Specialty segment	250	'
Industrial & Specialty Products segment, description	'Over 250 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.	'
Goodwill	$68,403	$68,403
Goodwill Related Segment [Member]	'	'
Segment Reporting Information [Line Items]	'	'
Goodwill	68,400	'
Oil & Gas Proppants [Member]	'	'
Segment Reporting Information [Line Items]	'	'
Goodwill	47,700	'
Industrial & Specialty Products [Member]	'	'
Segment Reporting Information [Line Items]	'	'
Goodwill	$20,700	'

Segment_Reporting_Presentation

Segment Reporting - Presentation of Sales and Segment Contribution Margin for Reporting Segments and Other Operating Results (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting Information [Line Items]	'	'
Total sales	$180,095	$122,311
Total segment contribution margin	54,815	49,408
Operating activities excluded from segment cost of goods sold	-1,490	-1,509
Selling, general and administrative	-15,445	-12,404
Depreciation, depletion and amortization	-9,589	-8,278
Interest expense	-3,808	-3,576
Other income, net, including interest income	38	122
Income before income taxes	24,521	23,763
Operating Segments [Member] | Oil & Gas Proppants [Member]	'	'
Segment Reporting Information [Line Items]	'	'
Total sales	130,584	73,582
Total segment contribution margin	41,628	36,162
Operating Segments [Member] | Industrial & Specialty Products [Member]	'	'
Segment Reporting Information [Line Items]	'	'
Total sales	49,511	48,729
Total segment contribution margin	$13,187	$13,246