Document and Entity Information (USD $)	12 Months Ended
Document and Entity Information (USD $)	Dec. 31, 2013	Feb. 21, 2014	Jun. 28, 2013
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2013
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	FY
Entity Registrant Name	U.S. Silica Holdings, Inc.
Entity Central Index Key	0001524741
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		53,551,879
Entity Public Float			$ 735,673,841

Consolidated Balance Sheets (USD $)	Dec. 31, 2013	Dec. 31, 2012
Current Assets:
Cash and cash equivalents	$ 78,256,000	$ 61,022,000
Short-term investments	74,980,000
Accounts receivable, net	75,207,000	59,564,000
Inventories, net	64,212,000	39,835,000
Prepaid expenses and other current assets	11,104,000	6,738,000
Deferred income taxes, net	17,737,000	10,108,000
Total current assets	321,496,000	177,267,000
Property, plant and mine development, net	442,116,000	414,218,000
Debt issuance costs, net	5,255,000	2,111,000
Goodwill	68,403,000	68,403,000
Trade names	10,436,000	10,436,000
Customer relationships, net	6,120,000	6,531,000
Other assets	9,635,000	7,844,000
Total assets	863,461,000	686,810,000
Current Liabilities:
Book overdraft	4,659,000	5,390,000
Accounts payable	37,376,000	37,333,000
Dividends payable	6,709,000
Accrued liabilities	10,823,000	9,481,000
Accrued interest	41,000	2,000
Current portion of long-term debt	3,488,000	2,433,000
Income tax payable	1,037,000	20,596,000
Current portion of deferred revenue		4,855,000
Total current liabilities	64,133,000	80,090,000
Long-term debt	367,963,000	252,992,000
Liability for pension and other post-retirement benefits	36,802,000	52,747,000
Deferred income taxes, net	71,318,000	59,111,000
Other long-term obligations	13,951,000	10,176,000
Total liabilities	554,167,000	455,116,000
Stockholders' Equity:
Common stock	534,000	529,000
Preferred stock
Additional paid-in capital	174,799,000	163,579,000
Retained earnings	137,978,000	82,731,000
Treasury stock, at cost		(970,000)
Accumulated other comprehensive loss	(4,017,000)	(14,175,000)
Total stockholders' equity	309,294,000	231,694,000
Total liabilities and stockholders' equity	$ 863,461,000	$ 686,810,000

Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Statement [Abstract]
Sales	$ 149,474	$ 144,372	$ 129,828	$ 122,311	$ 118,846	$ 115,885	$ 104,599	$ 102,591	$ 545,985	$ 441,921	$ 295,596
Cost of goods sold (excluding depreciation, depletion and amortization)	102,875	90,983	80,297	74,412	70,988	69,706	58,920	56,921	348,567	256,535	181,196
Operating expenses
Selling, general and administrative	14,456	12,800	10,099	12,404	11,542	10,135	9,718	9,904	49,759	41,299	23,348
Advisory fees to parent											9,250
Depreciation, depletion and amortization	10,098	9,152	8,890	8,278	7,179	5,968	5,974	5,978	36,418	25,099	20,999
Total operating expenses	24,554	21,952	18,989	20,682	18,721	16,103	15,692	15,882	86,177	66,398	53,597
Operating income	22,045	31,437	30,542	27,217	29,137	30,076	29,987	29,788	111,241	118,988	60,803
Other (expense) income
Interest expense	(4,086)	(4,144)	(3,535)	(3,576)	(3,244)	(3,326)	(3,428)	(3,797)	(15,341)	(13,795)	(18,407)
Early extinguishment of debt		(480)							(480)		(6,043)
Other income, net, including interest income	152	260	63	122	3,931	348	179	154	597	4,612	1,062
Total other (expenses) income	(3,934)	(4,364)	(3,472)	(3,454)	687	(2,978)	(3,249)	(3,643)	(15,224)	(9,183)	(23,388)
Income before income taxes	18,111	27,073	27,070	23,763	29,824	27,098	26,738	26,145	96,017	109,805	37,415
Income tax (expense) benefit	(1,658)	(5,739)	(6,878)	(6,486)	(8,030)	(8,302)	(7,287)	(7,032)	(20,761)	(30,651)	(7,162)
Net income	$ 16,453	$ 21,334	$ 20,192	$ 17,277	$ 21,794	$ 18,796	$ 19,451	$ 19,113	$ 75,256	$ 79,154	$ 30,253
Earnings per share:
Basic	$ 0.31	$ 0.40	$ 0.38	$ 0.33					$ 1.42	$ 1.50	$ 0.61
Diluted	$ 0.31	$ 0.40	$ 0.38	$ 0.32					$ 1.41	$ 1.50	$ 0.61

Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 75,256	$ 79,154	$ 30,253
Other comprehensive income:
Unrealized gain (loss) on derivatives (net of tax of $66, $144 and $78 for 2013, 2012, and 2011, respectively)	103	227	123
Unrealized gain (loss) on investments (net of tax of $(17), $0 and $0 for 2013, 2012, and 2011, respectively)	(27)
Pension and other post-retirement benefits liability adjustment (net of tax of $6,419, $(1,299) and $(4,627) for 2013, 2012, and 2011, respectively)	10,082	(2,041)	(7,244)
Comprehensive income	$ 85,414	$ 77,340	$ 23,132

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Amount after tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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Consolidated Statements of Comprehensive Income (Parenthetical) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement Of Income And Comprehensive Income [Abstract]
Tax expenses on unrealized gain (loss) on derivatives	$ 66	$ 144	$ 78
Tax expense (benefit) on unrealized gain (loss) on investments	(17)	0	0
Tax expenses on pension and other post-retirement benefits liability adjustment	$ 6,419	$ (1,299)	$ (4,627)

Consolidated Statements of Stockholders' Equity (USD $) In Thousands	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings (Deficit) [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balance at Dec. 31, 2010	$ 97,564	$ 500		$ 102,519	$ (215)	$ (5,240)
Net income	30,253				30,253
Unrealized gain (loss) on derivatives	123					123
Minimum pension liability	(7,244)					(7,244)
Equity-based compensation	1,238			1,238
Excess tax benefit from equity-based compensation	0
Ending Balance at Dec. 31, 2011	121,934	500		103,757	30,038	(12,361)
Net income	79,154				79,154
Unrealized gain (loss) on derivatives	227					227
Minimum pension liability	(2,041)					(2,041)
Cash dividends declared ($0.375 and $0.50 per share of common stock for 2013 and 2012 respectively))	(26,461)				(26,461)
Equity-based compensation	2,330			2,330
Excess tax benefit from equity-based compensation	0
Issuance of common stock (January 2012 initial public offering at $17.00 per share, net of issuance costs of $9,171)	40,829	29		40,800
Issuance of treasury stock	102		102
Repurchase of common stock	(1,072)		(1,072)
Capital contributed by parent	16,692			16,692
Ending Balance at Dec. 31, 2012	231,694	529	(970)	163,579	82,731	(14,175)
Net income	75,256				75,256
Unrealized gain (loss) on derivatives	103					103
Minimum pension liability	10,082					10,082
Unrealized gain (loss) on short-term investments	(27)					(27)
Cash dividends declared ($0.375 and $0.50 per share of common stock for 2013 and 2012 respectively))	(20,009)				(20,009)
Equity-based compensation	3,039			3,039
Excess tax benefit from equity-based compensation	1,380			1,380
Proceeds from options exercised	7,942	5	1,136	6,801
Shares withheld for employee taxes related to vested restricted stock units	(166)		(166)
Ending Balance at Dec. 31, 2013	$ 309,294	$ 534		$ 174,799	$ 137,978	$ (4,017)

Consolidated Statements of Stockholders' Equity (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Common stock cash dividend declared, per share	$ 0.375	$ 0.50
Common stock issuance costs		$ 9,171
Common Stock [Member]
Issuance of common stock, per share		$ 17.00
Common stock issuance costs		9,171
Additional Paid-In Capital [Member]
Common stock issuance costs		$ 9,171
Retained Earnings (Deficit) [Member]
Common stock cash dividend declared, per share	$ 0.375	$ 0.50

Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating activities:
Net income	$ 75,256	$ 79,154	$ 30,253
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	36,418	25,099	20,999
Debt issuance amortization	680	515	265
Original issue discount amortization	209	168	157
Early extinguishment of debt	480		6,043
Deferred income taxes	4,578	1,095	(659)
(Gain)/loss on disposal of property, plant and equipment	(162)	(472)	(35)
Deferred revenue	(4,855)	(7,666)	(7,068)
Equity-based compensation	3,039	2,330	1,238
Excess tax benefit from equity-based compensation	(1,380)
Other	(5,757)	2,148	4,029
Changes in assets and liabilities:
Accounts receivable	(16,965)	(13,239)	(16,437)
Inventories	(24,377)	(10,528)	(6,889)
Prepaid expenses and other current assets	(4,532)	1,823	(5,370)
Income taxes	(18,179)	24,491	(1,745)
Accounts payable and accrued liabilities	1,385	8,458	25,388
Advisory services termination fee to Golden Gate Capital		(8,000)
Accrued interest	39	(1,657)	1,558
Liability for pension and other post-retirement benefits	574	(2,769)	(9,162)
Net cash provided by operating activities	46,451	100,950	42,565
Investing activities:
Capital expenditures	(60,470)	(105,719)	(66,745)
Purchase of short-term investments	(75,000)
Proceeds from sale of property, plant and equipment	357	1,258	106
Net cash used in investing activities	(135,113)	(104,461)	(66,639)
Financing activities:
Proceeds from issuance of common stock in initial public offering		50,000
Dividends paid	(13,300)	(26,461)
Repurchase of common stock		(1,072)
Issuance of treasury stock		102
Proceeds from options exercised	7,942
Excess tax benefit from equity-based compensation	1,380
Tax payments related to shares withheld for vested restricted stock units	(166)
Issuance of long-term debt	373,792		259,061
Issuance of short-term debt			3,932
Repayment of long-term debt	(257,976)	(2,600)	(240,476)
Repayment of short-term debt		(3,932)
Change in book overdraft	(731)	(198)	1,861
Prepayment penalties	(250)		(1,500)
Principal payments on capital lease obligations	(744)
Financing fees	(4,051)	(1,334)	(4,105)
Common stock issuance costs		(9,171)
Net cash provided by financing activities	105,896	5,334	18,773
Net increase (decrease) in cash and cash equivalents	17,234	1,823	(5,301)
Cash and cash equivalents, beginning of period	61,022	59,199	64,500
Cash and cash equivalents, end of period	78,256	61,022	59,199
Non-cash financing activities:
Contribution of note from parent and related accrued interest		16,692
Capital lease obligations incurred to acquire assets	744
Cash paid during the period for:
Interest	14,716	12,436	18,404
Taxes	$ 40,760	$ 3,883	$ 6,915

Organization	12 Months Ended
Organization	Dec. 31, 2013
Accounting Policies [Abstract]
Organization	NOTE A—ORGANIZATION U.S. Silica Holdings, Inc. (“Holdings,” and together with its subsidiaries “we,” “us” or the “Company”), formerly GGC USS Holdings, Inc., was organized as a holding company on November 14, 2008. On November 25, 2008, we acquired Hourglass Acquisitions I, LLC, whose only operating subsidiary was U.S. Silica Company (“U.S. Silica”). On November 25, 2008, we issued 1,000 shares of our common stock to our then sole stockholder, GGC USS Holdings, LLC (“GGC Holdings”), for an aggregate purchase price of $10.00. The shares were issued in reliance on Section 4(2) of the Securities Act because the sale of the securities did not involve a public offering. Appropriate legends were affixed to the securities issued in this transaction. On July 8, 2011, our Board of Directors approved, and we subsequently filed, an Amended and Restated Certificate of Incorporation which, among other things, increased the authorized shares of common stock to 100 million shares. The Amended and Restated Certificate of Incorporation also created a 50,000-for-one split of our common stock. All of our common stock share and per share data contained in the financial statements has been retroactively adjusted to reflect this stock split for all periods presented. On January 31, 2012, the Certificate of Incorporation was amended and restated to increase the authorized shares of common stock to 500 million shares, and to authorize 10 million shares of preferred stock. On January 31, 2012, we completed an initial public offering of common stock (the “IPO”) through a Registration Statement on Form S-1 (File No. 333-175636), pursuant to which we registered and issued 2,941,176 shares of our common stock, and we registered and certain of our stockholders sold 8,823,529 shares of common stock at an offering price of $17.00 per share. On February 6, 2012, we issued all 2,941,176 shares of common stock for an aggregate offering price of approximately $50.0 million and the selling stockholders sold all 8,823,529 shares of common stock for an aggregate offering price of approximately $150.0 million. As a result of the offering, we received net proceeds of approximately $40.8 million, after deducting $3.5 million of underwriting discounts and commissions and offering expenses of $5.7 million. On January 31, 2012, simultaneously with the initial public offering of our common stock, GGC Holdings, our sole stockholder prior to the IPO, contributed to us all of the stock of its wholly-owned subsidiary, GGC RCS Holdings, Inc., and its operating subsidiary, Coated Sand Solutions, LLC. Prior to this transaction, GGC RCS Holdings, Inc. had a $15.0 million note payable to GGC Holdings which, together with accrued interest of $1.7 million, was converted to an equity contribution by GGC Holdings, simultaneously with the IPO. Coated Sand Solutions develops resin-coated sand proppants for sale into the oil and gas proppants market for use in the hydraulic fracturing process and into the foundry market. As of December, 31, 2013, GGC USS Holdings, LLC held no interest in U.S. Silica after divesting its ownership interest in U.S. Silica during 2013.

- Definition

The entire disclosure for organization, consolidation and basis of presentation of financial statements disclosure.

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Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2013

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

NOTE B—SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Basis of Presentation and Consolidation

The consolidated financial statements as of December 31, 2013 and 2012 and for the years ended December 31, 2013, 2012 and 2011 (the “Financial Statements”), present our financial position, results of operations, and cash flows. In our opinion, our Financial Statements reflect all normal and recurring adjustments necessary to present fairly our financial position as of December 31, 2013 and 2012, the results of our operations for the years ended December 31, 2013, 2012 and 2011, and our cash flows for the year ended December 31, 2013, 2012 and 2011. 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.”

The Financial Statements include the accounts of Holdings and its direct and indirect wholly-owned subsidiaries and GGC RCS Holdings, Inc. (formed in 2010). In consideration of the contribution of GGC RCS Holdings, Inc. to us on January 31, 2012, we and our subsidiaries are presented on a consolidated basis with GGC RCS Holdings, Inc. as of and for the years ended December 31, 2013 and 2012. For the year ended December 31, 2011, we and our subsidiaries are presented on a combined basis with GGC RCS Holdings, Inc. All significant intercompany balances and transactions have been eliminated in combination.

We follow FASB Accounting Standards Codification (“ASC”) guidance for identification and reporting of entities over which control is achieved through means other than voting rights. The guidance defines such entities as Variable Interest Entities (“VIEs”). As of December 31, 2013 and for the periods presented herein, we have identified no entities over which we maintain any level of control that would qualify for consolidation under ASC guidance.

Use of Estimates and Assumptions

The Financial Statements have been prepared in accordance with United States generally accepted accounting principles (“GAAP”). 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 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.

Revenue Recognition

Revenue is recognized from a sale when persuasive evidence of an arrangement exists, the price is determinable, the product has been delivered or legal title has been transferred to the customer and collection of the sales price is reasonably assured. Amounts received from customers in advance of revenue recognition are deferred as liabilities.

We derive our sales by mining and processing minerals that our customers purchase for various uses. Our sales are primarily a function of the price per ton realized and the volumes sold. In some instances, our sales also include a charge for transportation services we provide to our customers. Our transportation revenue fluctuates based on a number of factors, including the volume of product we transport under contract, service agreements with our customers, the mode of transportation utilized and the distance between our plants and customers.

We primarily sell our products under short-term price agreements or at prevailing market rates. For a limited number of customers, we sell under long-term, competitively-bid supply agreements. For the year ended December 31, 2013, we had take-or-pay supply agreements with seven of our customers in the oil & gas proppants segment with initial terms expiring between 2013 and 2016. These agreements define, among other commitments, the volume of product that our customers must purchase, the volume of product that it must provide and the price that it will charge and that our customers will pay for each product. Prices under these agreements are generally fixed and subject to upward adjustment in response to certain cost increases. As a result, our realized prices may not grow at rates consistent with broader industry pricing. For example, during periods of rapid price growth, our realized prices may grow more slowly than those of competitors, and during periods of price decline, our realized prices may outperform industry averages.

We invoice the majority of our clients on a per shipment basis, although for some larger customers, we consolidate invoices weekly or monthly. Standard terms are net 30 days, although extended terms are offered in competitive situations. The amounts invoiced include the amount charged for the product, transportation costs (if paid by us) and costs for additional services as applicable, such as costs related to transload the product from railcars to trucks for delivery to the customer site.

Cash and Cash Equivalents

Cash and cash equivalents consist of all highly liquid investments with a maturity of three months or less when purchased. Because of the short maturity of these investments, the carrying amounts approximate their fair value. Cash and cash equivalents are invested primarily in money market securities with high quality institutions. Accounts at each institution are insured by Federal Deposit Insurance Corporation. Cash balances at times may exceed federally-insured limits. We have not experienced any losses in such accounts and believe we are not exposed to any significant credit risk on cash.

Accounts Receivable

The majority of our accounts receivable are due from companies in the glass, oil and natural gas drilling, building products, filler and extenders, foundries and other major industries. Credit is extended based on evaluation of a customer’s financial condition and, generally, collateral is not required. Accounts receivable are generally due within 30 days and are stated at amounts due from customers net of an allowance for doubtful accounts. Accounts outstanding longer than the payment terms are considered past due. We determine our allowance by considering a number of factors, including the length of time trade accounts receivable are past due, our previous loss history, the customer’s current ability to pay its obligation to us, and the condition of the general economy and the industry as a whole. We write-off accounts receivable when they are deemed uncollectible, and payments subsequently received on such receivables are credited to the allowance for doubtful accounts.

Our ten largest customers accounted for approximately 52%, 37% and 44% of sales in the years ended December 31, 2013, 2012 and 2011, respectively. No single individual customer accounted for more than 10% of sales in the years ended December 31, 2013, 2012 and 2011. Management believes it maintains adequate reserves for potential credit losses; ongoing credit evaluations are performed and collateral is generally not required.

Inventories

Property, Plant and Mine Development

Property and equipment

Property and equipment is recorded at cost and depreciated over their estimated useful lives. Interest incurred during construction of facilities is capitalized and depreciated over the life of the asset. Depreciable properties, mining properties, and mineral deposits acquired in connection with business acquisitions are recorded at fair market value as of the date of acquisition.

Costs for normal repairs and maintenance that do not extend economic life or improve service potential are expensed as incurred. Costs of improvements that extend economic life or improve service potential are capitalized and depreciated over the estimated remaining useful life.

Depreciation is recorded using the straight-line method over the assets’ estimated useful life as follows: buildings (15 years); land improvements (10 years); machinery & equipment, including computer equipment and software (3-10 years); furniture & fixtures (8 years). Leasehold improvements are depreciated over the shorter of the asset life or lease term. Construction-in-progress is primarily comprised of machinery and equipment, which has not yet been placed in service.

Gains on the sale of assets are included in income when the assets are disposed of provided there is more than reasonable certainty of the collectability of the sales price and any future activities required to be performed by us relating to the disposal of the assets are complete or insignificant. Upon retirement or disposal of assets, all costs and related accumulated depreciation or amortization are written-off.

Depletion and amortization of mineral deposits are recorded as the minerals are extracted, based on units of production and engineering estimates of mineable reserves. The impact of revisions to reserve estimates is recognized on a prospective basis.

We evaluate the carrying value of our property and equipment if impairment evaluation triggering events occur. If it is determined that the current net book value is in excess of the fair value, the excess of the net book value over the estimated fair value is recorded in our consolidated statements of operations as impairment loss. Fair value is generally estimated using valuation techniques that consider the discounted cash flows of the asset at rates deemed reasonable for the type of asset and prevailing market conditions, appraisals, including recent similar transactions in the market and if appropriate and available, current estimated net sales proceeds from pending offers.

We will classify an asset as held for sale when we have committed to a plan to sell the asset, the sale of the asset is probable within one year, and actions to complete the sale are unlikely to change or that the sale will be withdrawn. Accordingly, we typically classify assets as held for sale when our Board of Directors has approved the sale, a binding agreement to purchase the property has been signed under which the buyer has committed a significant amount of nonrefundable cash and no significant financing contingencies exist which could prevent the transaction from being completed in a timely manner. If these criteria are met, we will record an impairment loss if the fair value, less cost to sell, is lower than the carrying amount of the asset and will cease recording depreciation. We will classify the loss, together with the related operating results, including related interest expense on any debt assumed by the buyer or that is required to be repaid as a result of the sale, as discontinued operations on our consolidated statement of operations, presuming that we will not have continuing involvement with the property or asset after the sale, and classify the asset and related liability as held for sale on our consolidated balance sheet. Gains on sales of assets are recognized at the time of sale or deferred and recognized as income in subsequent periods as conditions requiring deferral are satisfied or expire without further cost to us.

Mine exploration and development

Mine exploration and development costs include engineering and mineral studies, drilling and other related costs to delineate an ore body, and the removal of overburden to initially expose an ore body for production. Costs incurred before mineralization are classified as proven and probable reserves are expensed and classified as exploration or advanced projects, research and development expense. Capitalization of mine development project costs, that meet the definition of an asset, begins once mineralization is classified as proven and probable reserves.

Drilling and related costs are capitalized for an ore body where proven and probable reserves exist and the activities are directed at obtaining additional information on the ore body or converting non-reserve mineralization to proven and probable reserves and the benefit is expected to be realized over a period beyond one year. All other drilling and related costs are expensed as incurred. Drilling costs incurred during the production phase for operational ore control are allocated to inventory costs and then included as a component of costs applicable to sales.

The cost of removing overburden and waste materials to access the ore body at an open pit mine prior to the production phase are referred to as “pre-stripping costs.” Pre-stripping costs are capitalized during the development of an open pit mine. Where multiple open pits exist at a mining complex utilizing common processing facilities, pre-stripping costs are capitalized at each pit. The removal, production, and sale of de minimis saleable materials may occur during development and are recorded as other income, net of incremental mining and processing costs.

The production phase of an open pit mine commences when saleable minerals, beyond a de minimis amount, are produced. Stripping costs incurred during the production phase of a mine are variable production costs that are included as a component of inventory to be recognized in costs applicable to sales in the same period as the revenue from the sale of inventory. Our definition of a mine and the mine’s production phase may differ from that of other companies in the mining industry resulting in incomparable allocations of stripping costs to deferred mine development and production costs. Other mining companies may expense pre-stripping costs associated with subsequent pits within a mining complex.

Mine development costs are amortized using the units-of-production method based on estimated recoverable tons in proven and probable reserves. To the extent that these costs benefit an entire ore body, they are amortized over the estimated life of the ore body. Costs incurred to access specific ore blocks or areas that only provide benefit over the life of that area are amortized over the estimated life of that specific ore block or area.

Mine reclamation costs

We recognize the fair value of any liability for conditional asset retirement obligations, including environmental remediation liabilities when incurred, which is generally upon acquisition, construction or development and/or through the normal operation of the asset, if sufficient information exists to reasonably estimate the fair value of the liability. These obligations generally include the estimated net future costs of dismantling, restoring and reclaiming operating mines and related mine sites, in accordance with federal, state and local regulatory requirements. The liability is accreted over time through periodic charges to earnings. In addition, the asset retirement cost is capitalized as part of the asset’s carrying value and amortized over the life of the related asset. Reclamation costs are periodically adjusted to reflect changes in the estimated present value resulting from the passage of time and revisions to the estimates of either the timing or amount of the reclamation and abandonment costs. The reclamation obligation is based on when spending for an existing environmental disturbance will occur. If the asset retirement obligation is settled for other than the carrying amount of the liability, a gain or loss is recognized on settlement. We review, on an annual basis, unless otherwise deemed necessary, the reclamation obligation at each mine site in accordance with ASC guidance for accounting reclamation obligations.

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.

In connection with our annual review of our reclamation obligations in 2013, we have determined that some of our estimates required revision due primarily to the addition of our new transload facility in San Antonio, Texas and to other changes in cost estimates and settlement dates at numerous sites. These changes in estimates resulted in the addition of $2.3 million of reclamation obligations in 2013.

We reported a liability of $9.4 million and $6.7 million in other long-term obligations related to this obligation as of December 31, 2013 and 2012, respectively. Changes in the asset retirement obligation are as follows:


	2013		2012
Beginning balance	$	6,659	$	9,504
Payments		—		—
Accretion		456		658
Revisions of prior estimates		2,263		(3,503	)

Ending balance	$	9,378	$	6,659

Goodwill and Other Intangible Assets and Related Impairment

Our intangible assets consist of goodwill, which is not being amortized; indefinite lived intangibles, which consist of certain trade names that are not subject to amortization; and customer relationships, which are being amortized on a straight-line basis over their useful life of 20 years. Goodwill represents the excess of purchase price over the fair value of net assets from the business acquisition in 2008.

Goodwill and other intangible assets with indefinite lives are reviewed for impairment annually as of October 31 or more frequently whenever events or circumstances change that would more likely than not reduce the fair value of those assets. Prior to conducting a formal impairment test, we assess qualitative factors to determine whether the existence of events or circumstances leads to a determination that is more likely than not (more than 50%) that the fair value of a reporting unit is less than its carrying amount. Such qualitative factors may include the following: macroeconomic conditions; industry and market considerations; cost factors; overall financial performance; and other relevant entity-specific events.

If the qualitative assessment determines that an impairment is more likely than not, then the impairment test for goodwill, or other intangible assets with indefinite lives, requires a comparison of the fair value with the carrying amount, including goodwill. If this comparison reflects impairment, then the loss would be measured as the excess of recorded goodwill, or other intangible assets with indefinite lives, over its implied fair value. Implied fair value is the excess of our fair value over the fair value of all recognized and unrecognized assets and liabilities.

The evaluation of goodwill, or other intangible assets with indefinite lives, for possible impairment includes estimating our fair value using discounted cash flows and multiples of cash earnings valuation techniques, plus valuation comparisons to similar businesses. These valuations require us to make estimates and assumptions regarding future operating results, cash flows, changes in working capital and capital expenditures, selling prices, profitability, and the cost of capital. Although we believe that the estimates and assumptions used were reasonable, actual results could differ from those estimates and assumptions. As of December 31, 2013 our qualitative assessment did not indicate that it was more likely than not that an impairment had occurred.

As of December 31, 2013, the gross carrying amount of the customer relationships intangible asset was $8.2 million with accumulated amortization of $2.1 million. We review all finite-lived intangible assets for impairment when circumstances indicate that their carrying amounts may not be recoverable. We evaluate the carrying value of all finite-lived intangible assets for impairment by comparing the expected undiscounted future cash flows of the asset to the net book value of the asset. If the expected undiscounted future cash flows are less than the net book value of the assets, the excess of the net book value over the estimated fair value is recorded in our consolidated statements of operations as impairment loss. Fair value is generally estimated using valuation techniques that consider the discounted cash flows of the asset at rates deemed reasonable for the type of asset and prevailing market conditions, replacement cost, appraisals, including recent similar transactions in the market and if appropriate, current estimated net sales proceeds from pending offers. As of December 31, 2013, the remaining useful life of our customer relationships was 14.9 years. The estimated annual amortization in each of the next five years is $411.

Debt Issuance Costs

Debt issuance costs consist of loan origination costs, which are being amortized using the effective interest method over the term of the related debt principal. Amortization included in interest expense was $680, $515 and $265 for the years ended December 31, 2013, 2012 and 2011, respectively.

Transportation Revenue and Expense

Transportation revenue is the revenue we receive from charging our customers to deliver product to their locations. Revenue is recognized from a sale when persuasive evidence of an arrangement exists, the price is determinable, the product has been delivered or legal title has been transferred to the customer and collection of the sales price is reasonably assured. Transportation expense is the cost we pay to ship product from our production facilities to customer facilities.

Environmental Costs

Environmental costs, other than qualifying capital expenditures, are accrued at the time the exposure becomes known and costs can be reasonably estimated. Costs are accrued based upon management’s estimates of all direct costs, after taking into account expected reimbursement by third parties (primarily the sellers of acquired businesses), and are reviewed by outside consultants. Environmental costs are charged to expense unless a settlement with an indemnifying party has been reached.

Self-Insurance

We are self-insured for various levels of employee health insurance coverage, workers’ compensation and third party product liability claims alleging occupational disease. We purchase insurance coverage for claim amounts which exceed our self-insured retentions. Depending on the type of insurance, these self-insured retentions range from $100,000 to $500,000 per occurrence.

Our insurance reserves are accrued based on estimates of the ultimate cost of claims expected to occur during the covered period. These estimates are prepared with the assistance of outside actuaries and consultants. Our actuaries periodically review the volume and amount of claims activity, and based upon their findings, we adjust our insurance reserves accordingly. The ultimate cost of claims for a covered period may differ from our original estimates.

The current portion of our self-insurance reserves is included in accrued liabilities and the non-current portion is included in other long-term obligations in our consolidated balance sheets. Our self-insurance reserves totaled $5.4 million and $4.0 million at December 31, 2013 and 2012, respectively. Of these amounts, $1.7 million and $1.3 million, respectively, were classified as current.

Equity-based Compensation

We recognize the cost of employee services rendered in exchange for awards of equity instruments, such as stock options and restricted stock, based on the fair value of those awards at the date of the grant. Compensation expense for equity units is recognized, on a straight-line basis, net of forfeitures, over the requisite service period for the fair value of the awards that actually vest.

Income Taxes

Deferred taxes are provided on the liability method whereby deferred tax assets are recognized for deductible temporary differences and operating loss and tax credit carry forwards and deferred tax liabilities are recognized for taxable temporary differences. This approach requires recognition of deferred tax liabilities and assets for the expected future tax consequences of events that have been included in the financial statements or tax returns. Under this method, deferred tax liabilities and assets are determined based upon the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the expenses are expected to reverse. Valuation allowances are provided if, based on the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized.

We recognize a tax benefit associated with an uncertain tax position when, in management’s judgment, it is more likely than not that the position will be sustained upon examination by a taxing authority. For a tax position that meets the more-likely-than-not recognition threshold, we initially and subsequently measure the tax benefit as the largest amount that it judges to have a greater than 50% likelihood of being realized upon ultimate settlement with a taxing authority. The liability associated with unrecognized tax benefits is adjusted periodically due to changing circumstances, such as the progress of tax audits, case law developments and new or emerging legislation. Such adjustments are recognized entirely in the period in which they are identified. The effective tax rate includes the net impact of changes in the liability for unrecognized tax benefits and subsequent adjustments as considered appropriate by management.

The largest permanent item in computing both our effective tax rate and taxable income is the deduction allowed for statutory depletion. The impact of statutory depletion on the effective tax rate is presented in Note Q to these financial statements. The deduction for statutory depletion does not necessarily change proportionately to changes in income before income taxes.

Net Income per Common Share

Basic and diluted income per share is presented for net income. Basic income per share is computed by dividing income available to common stockholders by the weighted-average number of outstanding common shares for the period. Diluted income per share reflects the potential dilution that could occur if securities or other contracts that may require the issuance of common shares in the future were converted. Diluted income per share is computed by increasing the weighted-average number of outstanding common shares to include the additional common shares that would be outstanding after conversion and adjusting net income for changes that would result from the conversion. Only those securities or other contracts that result in a reduction in earnings per share are included in the calculation.

Comprehensive Income

In addition to net income, comprehensive income (loss) includes all changes in equity during a period, such as adjustments to minimum pension liabilities and the effective portion of changes in fair value of derivative instruments that qualify as cash flow hedges.

Short-Term Investments

Our short-term investments consist of fixed income securities that have been classified and accounted for as available-for-sale. We determine the appropriate classification of our investments at the time of purchase and reevaluate the designations at each balance sheet date. We classify these securities as either short-term or long-term based on each instrument’s underlying contractual maturity date. Fixed income securities with maturities of 12 months or less are classified as short-term and fixed income securities with maturities greater than 12 months are classified as long-term. These investments are carried at fair value, with the unrealized gains and losses, net of taxes, reported as a separate component of accumulated other comprehensive income. The cost of securities sold is based upon the specific identification method.

Financial Instruments

We currently use interest rate hedge agreements and have historically utilized natural gas hedge agreements to manage interest and energy costs and the risk associated with changing interest rates and natural gas prices. Amounts to be paid or received under these hedge agreements are accrued as interest rates or natural gas prices change and are recognized over the life of the hedge agreements as an adjustment to interest expense or, in the case of natural gas, cost of goods sold. Our policy is to not hold or issue derivative financial instruments for trading or speculative purposes. When entered into, these financial instruments are designated as hedges of underlying exposures, associated with our long-term debt and energy costs, and are monitored to determine if they remain effective hedges. Gains and losses on derivatives designated as cash flow hedges are recorded in other comprehensive income net of tax and reclassified to earnings in a manner that matches the timing of the earnings impact of the hedged transactions. The ineffective portion of all hedges, if any, is recognized currently in income. Additional disclosures for derivative instruments are presented in Note M to these financial statements.

Recently Adopted Accounting Pronouncements

In February 2013, the FASB issued ASU 2013-02, “Comprehensive Income (“ASC Topic 220”): Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income,” which requires entities to provide information about the amounts reclassified out of accumulated other comprehensive income by component. In addition, entities are required to present, either on the face of the statement where net income is presented or in the notes, significant amounts reclassified out of accumulated other comprehensive income by the respective line items of net income but only if the amount reclassified is required under U.S. Generally Accepted Accounting Principles (“U.S. GAAP”) to be reclassified to net income in its entirety in the same reporting period. For other amounts that are not required under U.S. GAAP to be reclassified in their entirety to net income, entities are required to cross-reference to other disclosures required under U.S. GAAP that provide additional detail on these amounts. We adopted this guidance, effective for the 2013 reporting period with no material impact on our Financial Statements.

In July 2013, the FASB amended Accounting Standards Codification (“ASC Topic 740”), “Income Taxes.” The amendment provides guidance on the financial statement presentation of an unrecognized tax benefit, as either a reduction of a deferred tax asset or as a liability, when a net operating loss carry-forward, a similar tax loss or a tax credit carry-forward exists. The amendment will be effective for interim and annual periods beginning after December 15, 2013 and may be applied on a retrospective basis. Early adoption is permitted. We do not expect the adoption of this amendment to have a significant effect on our consolidated financial position or results of operations.

- Definition

The entire disclosure for all significant accounting policies of the reporting entity.

+ References+ Details

Earnings Per Share

12 Months Ended

Dec. 31, 2013

Earnings Per Share [Abstract]

Earnings Per Share

NOTE C—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.


	For the Year Ended December 31,
	2013			2012			2011
Net income	$	75,256		$	79,154		$	30,253
Less: net income allocated to outstanding restricted stockholders		(175	)		(105	)		—

Net income allocated to common stockholders	$	75,081		$	79,049		$	30,253

Weighted-average common stock
Outstanding		53,035			52,592			50,000
Outstanding assuming dilution		53,409			52,641			50,006

- Definition

The entire disclosure for earnings per share.

+ References+ Details

Capital Structure and Accumulated Comprehensive Income

12 Months Ended

Dec. 31, 2013

Equity [Abstract]

Capital Structure and Accumulated Comprehensive Income

NOTE D—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 53,492,278 shares of common stock issued and outstanding at December 31, 2013. As of December 31, 2012, there were 52,920,704 shares issued and outstanding. On October 24, 2013, 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 December 16, 2013, payable on January 3, 2014.

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 December 31, 2013 and 2012. At present, we have no plans to issue any preferred stock.

Share Repurchase Program

On June 11, 2012, the 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, the 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 December 31, 2013, 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 December 31, 2013, 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 year ended December 31, 2013:


	For the Year Ended December 31, 2013
	Unrealized gain/(loss) on cash flow hedges			Unrealized gain/(loss) on short-term investments			Pension and other post- retirement benefits liability			Total
Beginning Balance	$	(182	)	$	—		$	(13,993	)	$	(14,175	)
Other comprehensive income (loss) before reclassifications		(82	)		(27	)		8,844			8,735
Amounts reclassed from accumulated other comprehensive income		185			—			1,238			1,423

Ending Balance	$	(79	)	$	(27	)	$	(3,911	)	$	(4,017	)

The following table presents the reclassifications out of accumulated other comprehensive income (loss) during the year ended December 31, 2013:


Details about accumulated other comprehensive income	Amount reclassified from accumulated other comprehensive income			Affected line item in the statement of operations
Gains and losses on cash flow hedges
Interest rate contracts	$	304			Interest expense
		(119	)		Tax expense

	$	185			Net of tax

Amortization of postretirement benefits liability
Actuarial gains/(losses)	$	1,933			⁽¹	⁾
Prior service cost		92			⁽¹	⁾

	$	2,025			Total before tax
		(787	)		Tax expense

		1,238			Net of tax

Total reclassifications for the period	$	1,423			Net of tax

⁽¹⁾	These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see Note R).

- Definition

The entire disclosure for comprehensive income, which includes, but is not limited to, 1) the amount of income tax expense or benefit allocated to each component of other comprehensive income, including reclassification adjustments, 2) the reclassification adjustments for each classification of other comprehensive income and 3) the ending accumulated balances for each component of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 11

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-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

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-Name Accounting Standards Codification

-Glossary Reclassification Adjustments

-URI http://asc.fasb.org/extlink&oid=6522872

+ Details

Accounts Receivable

12 Months Ended

Dec. 31, 2013

Receivables [Abstract]

Accounts Receivable

NOTE E—ACCOUNTS RECEIVABLE

At December 31, 2013 and 2012, accounts receivable consisted of the following:


	At December 31,
	2013			2012
Trade receivables	$	76,223		$	56,519
Less: Allowance for doubtful accounts		(2,376	)		(1,053	)

Net trade receivables		73,847			55,466
Other receivables		1,360			4,098

Total accounts receivable	$	75,207		$	59,564

Net trade receivables increased $18,381 to $73,847 as of December 31, 2013 compared to $55,466 as of December 31, 2012, primarily due to the increase in sales. No single individual customer accounted for more than 10% of sales in the years ended December 31, 2013, 2012 and 2011.

- Definition

The entire disclosure for claims held for amounts due a entity, excluding financing receivables. Examples include, but are not limited to, trade accounts receivables, notes receivables, loans receivables. Includes disclosure for allowance for credit losses.

+ References+ Details

Inventories

12 Months Ended

Dec. 31, 2013

Inventory Disclosure [Abstract]

Inventories

NOTE F—INVENTORIES

At December 31, 2013 and 2012, inventories consisted of the following:


	At December 31,
	2013		2012
Supplies	$	15,576	$	13,472
Raw materials and work in process		11,728		10,720
Finished goods		36,908		15,643

Total inventories	$	64,212	$	39,835

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 increased $21,265 to $36,908 as of December 31, 2013 compared to $15,643 as of December 31, 2012, primarily due to an increase of inventory held at transloads.

- Definition

The entire disclosure for inventory. This may include, but is not limited to, the basis of stating inventory, the method of determining inventory cost, the major classes of inventory, and the nature of the cost elements included in inventory. If inventory is stated above cost, accrued net losses on firm purchase commitments for inventory and losses resulting from valuing inventory at the lower-of-cost-or-market may also be included. For LIFO inventory, may disclose the amount and basis for determining the excess of replacement or current cost over stated LIFO value and the effects of a LIFO quantities liquidation that impacts net income.

+ References+ Details

Property, Plant and Mine Development

12 Months Ended

Dec. 31, 2013

Property Plant And Equipment [Abstract]

Property, Plant and Mine Development

NOTE G—PROPERTY, PLANT AND MINE DEVELOPMENT

At December 31, 2013 and 2012, property, plant and mine development consisted of the following:


	At December 31,
	2013			2012
Mining property and mine development	$	164,609		$	163,538
Asset retirement cost		7,275			5,124
Land		25,738			24,795
Land improvements		31,093			27,604
Buildings		36,311			31,558
Machinery and equipment		263,304			221,139
Furniture and fixtures		1,131			915
Construction-in-progress		25,974			18,049

		555,435			492,722
Accumulated depletion, depreciation and amortization		(113,319	)		(78,504	)

Total property, plant and mine development, net	$	442,116		$	414,218

Depreciation expense, including depletion and amortization, recognized during the year ended December 31, 2013, 2012 and 2011 was $36,418, $25,099 and $20,999, respectively. The amount of interest costs capitalized in property, plant and equipment was $533, $934 and $575 for the year ended December 31, 2013, 2012 and 2011, respectively. As of December 31, 2013, we hold no assets under a capital lease obligation.

- Definition

The entire disclosure for long-lived, physical assets used in the normal conduct of business and not intended for resale. Includes, but is not limited to, accounting policies and methodology, roll forwards, depreciation, depletion and amortization expense, including composite depreciation, accumulated depreciation, depletion and amortization expense, useful lives and method used, income statement disclosures, assets held for sale and public utility disclosures.

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Accrued Liabilities

12 Months Ended

Dec. 31, 2013

Payables And Accruals [Abstract]

Accrued Liabilities

NOTE H—ACCRUED LIABILITIES

At December 31, 2013 and 2012, accrued liabilities consisted of the following:


	At December 31,
	2013		2012

Accrued salaries and wages	$	2,411	$	2,939
Accrued vacation liability		2,396		2,397
Current portion of liability for pension and post-retirement benefits		1,428		1,413
Accrued healthcare liability		1,662		1,278
Other accrued liabilities		2,926		1,454

Total accrued liabilities	$	10,823	$	9,481

We are self-insured for health care claims for eligible participating employees and qualified dependent medical claims, subject to deductibles and limitations. Our liabilities for claims incurred but not reported (IBNR) are determined based on an estimate of the ultimate aggregate liability for claims incurred. The estimate is calculated from actual historical claim rates and reviewed and adjusted periodically, as necessary.

Other accrued liabilities consist of taxes payable, accrued shipping costs, royalties payable, and other immaterial items.

Debt

12 Months Ended

Dec. 31, 2013

Debt Disclosure [Abstract]

Debt

NOTE I—DEBT

As discussed below, on July 23, 2013, we refinanced our existing senior secured debt by amending our Term Loan and replacing our existing revolving line-of-credit. At December 31, 2013 and 2012, debt consisted of the following:


	December 31, 2013			December 31, 2012
Revolving line-of-credit:	$	—	⁽¹⁾	$	—	⁽²⁾
⁽¹⁾ Revolver expiring July 23, 2018 (4.75% at December 31, 2013)
⁽²⁾ Revolver expiring October 31, 2016 (5.0% at December 31, 2012); replaced by ⁽¹⁾on July 23, 2013
Senior secured credit facility:		371,451			255,425
Term loan facility—final maturity July 23, 2020 (4% at December 31, 2013 and 4.75% at December 31, 2012), net of unamortized original issue discount of $1,674 and $675, respectively

Total debt		371,451			255,425
Less: current portion		(3,488	)		(2,433	)

Total long-term portion of debt	$	367,963		$	252,992

Revolving Line-of-Credit

As of December 31, 2013, the available borrowing base under our revolving line-of-credit (the “Revolver”) was $50 million, with zero drawn as of that date and $9.0 million allocated for letters of credit, leaving $41.0 million available for general corporate use under this revolving credit agreement.

Debt Maturities

At December 31, 2013, contractual maturities of long-term debt are as follows:


2014		3,488
2015		3,490
2016		3,493
2017		3,495
2018		3,499
Thereafter		353,986

	$	371,451

On January 31, 2012, we amended our senior secured term loan facility (the “Term Loan”). The primary revisions to the Term Loan were to eliminate a requirement to provide monthly financial reports, to remove financial covenant restrictions related to capital expenditures, to provide flexibility to make investments and acquisitions and to incur indebtedness, and to provide a new subsidiary guarantee from Coated Sand Solutions, LLC.

On December 31, 2012, we amended our Revolver. The primary revisions to the Revolver included an increase of the commitment under the Revolver from $35 million to $50 million, and the letter of credit sublimit from $15 million to $20 million; provided, however, that the aggregate principal amount of the loans and letters of credit obligations outstanding at any one time shall not exceed the borrowing base as calculated pursuant to the agreement. The amendment also extended the termination date of the Revolver from October 31, 2015 to October 31, 2016, reduced prices and fees on borrowings, letters of credit and unused commitments and added an additional subsidiary, Coated Sand Solutions, LLC, as a co-borrower.

On July 23, 2013, we refinanced our existing senior secured debt by amending our Term Loan and replacing our existing revolving line-of-credit. The Term Loan amendment refinanced our existing senior debt by entering into a new $425 million senior secured credit facility, consisting of a $375 million Term Loan and the $50 million Revolver that may also be used for swingline loans (up to $5 million) or letters of credit (up to $20 million). The Term Loan amendment also, among other things, removed and amended certain financial and other covenants to provide additional operating flexibility, and lowered interest rates on borrowed amounts. The existing revolving line-of-credit was terminated. The Term Loan will expire on July 23, 2020 and the Revolver will expire on July 23, 2018. As a result of refinancing our Term Loan and replacing our revolving line-of-credit, we expensed $1.8 million of costs, consisting of $1.3 million related to third party fees in selling, general, and administrative expenses and $0.5 million related to early extinguishment of debt.

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 December 31, 2013, we are in compliance with all covenants in accordance with our senior secured credit facility.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References+ Details

Deferred Revenue	12 Months Ended
Deferred Revenue	Dec. 31, 2013
Revenue Recognition [Abstract]
Deferred Revenue	NOTE J—DEFERRED REVENUE On November 25, 2008, we, through an affiliate, received advances from two customers totaling $27 million. The deposits give these customers the right to purchase certain products for a fixed price at certain minimum volumes. In addition, the customers have security on their deposit in the form of promissory notes with an affiliate collateralized by undivided mineral interests in our mineral deposits. These notes originally bore interest at 10% compounded quarterly, to the extent any interest is unpaid. The obligations and related interest are reduced as shipments occur with a portion of the sales price being received in cash and a smaller noncash portion reducing first any accrued interest and then, to the extent available, any outstanding principal. As such, the notes do not require any payments in cash. The notes mature on December 31, 2015 and November 25, 2016. In December 2009, $12 million of the notes were amended to reduce the interest rate to 5%, retroactive to November 25, 2008. Effective January 1, 2010, the remaining $15 million was amended to reduce the interest rate to 6%, prospectively.

Fair Value Accounting

12 Months Ended

Dec. 31, 2013

Fair Value Disclosures [Abstract]

Fair Value Accounting

NOTE K—FAIR VALUE ACCOUNTING

Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Fair value is estimated by applying the following hierarchy, which prioritizes the inputs used to measure fair value into three levels and bases the categorization within the hierarchy upon the lowest level of input that is available and significant to the fair value measurement:

Level 1—Quoted prices in active markets for identical assets or liabilities

Level 2—Observable inputs other than quoted prices in active markets for identical assets and liabilities, 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 December 31, 2013 and 2012 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 December 31, 2013, 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 December 31, 2013 and 2012, respectively, of those assets that we measure at fair value on a recurring basis:


	December 31, 2013						December 31, 2012
	Level 1		Level 2		Total		Level 1		Level 2		Total
Short-term investments	$	622	$	74,358	$	74,980	$	—	$	—	$	—
Interest rate derivatives		—		109		109		—		—		—

Net asset	$	622	$	74,467	$	75,089	$	—	$	—	$	—

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References+ Details

Short-Term Investments

12 Months Ended

Dec. 31, 2013

Investments Debt And Equity Securities [Abstract]

Short-Term Investments

NOTE L—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 December 31, 2013:


	Aggregate Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Money market mutual funds	$	622	$	—	$	—		$	622
Fixed income securities:
Certificates of deposit		25,218		—		(34	)		25,184
Commercial paper		15,168		4		(1	)		15,171
Corporate notes and bonds		9,495		—		(9	)		9,486
Government agencies		13,979		6		—			13,985
U.S. Treasuries		4,828		—		(10	)		4,818
Variable Rate Demand Obligations		5,714		—		—			5,714

Total available-for-sale investments	$	75,024	$	10	$	(54	)	$	74,980

As of December 31, 2013, 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. During 2013, 2012 and 2011 we did not recognize any impairment charges.

- Definition

The entire disclosure for investments in certain debt and equity securities.

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+ Details

Derivative Instruments

12 Months Ended

Dec. 31, 2013

Derivative Instruments And Hedging Activities Disclosure [Abstract]

Derivative Instruments

NOTE M—DERIVATIVE INSTRUMENTS

We are exposed to certain risk arising from both our business operations and economic conditions. We principally manage our exposure to a wide variety of business and operation risks through management of our core business activities. Specifically, we enter into derivative financial instruments to manage exposures that arise from business activities that result in the receipt or payment of future known and unknown cash amounts, the value of which are determined by interest rates. Interest rate derivatives are utilized in the normal course of business to manage our interest cost and the risk associated with changing interest rates. We do not use derivative financial instruments for trading or speculative purposes. By their nature, all such instruments involve risk, including the possibility that a loss may occur from the failure of another party to perform according to the terms of a contract (credit risk) or the possibility that future changes in market price may make a financial instrument less valuable or more onerous (market risk). As is customary for these types of instruments, we do not require collateral or other security from other parties to these instruments. In management’s opinion, there is no significant risk of loss in the event of nonperformance of the counterparties to these financial instruments.

Cash Flow Hedges of Interest Rate Risk

Our objectives in using interest rate derivatives are to add stability to interest expense and to manage our exposure to interest rate movements. To accomplish this objective, we primarily use interest rate cap agreements as part of our interest rate risk management strategy. Interest rate caps designated as cash flow hedges involve the receipt of variable-rate amounts from a counterparty if interest rates rise above the strike rate on the contract in exchange for an upfront premium.

In connection with the Term Loan, we entered into two interest rate cap agreements that effectively place an upper limit for one-month LIBOR at 4.0% on the interest rate charged for $130.0 million of our floating rate Term Loan. On March 31, 2012, one of the agreements with a notional amount of $100.0 million matured. Concurrently with the maturity, the notional amount of a second agreement with an original notional amount of $30.0 million automatically increased to $130.0 million per the terms of the contract. On June 30, 2013 the second agreement matured. No additional expense was reclassified from accumulated other comprehensive income or recognized directly in earnings as a result of the maturity or adjustment. We entered into two interest rate cap agreements on April 8, 2013 and September 6, 2013 with a notional amount of $128 million and $60 million, respectively, which effectively place an upper limit for three-month LIBOR at 4.0%. We assess the effectiveness of our hedges in offsetting the variability in the cash flow of the hedged obligations on a quarterly basis. The effective portion of changes in the fair value of derivatives designated and that qualify as cash flow hedges is recorded in equity as accumulated other comprehensive income and is subsequently reclassified into earnings in the period that the hedged forecasted transaction affects earnings. The ineffective portion of the change in fair value of the derivatives is recognized directly in earnings. During the year ended December 31, 2013 and 2012, we had no ineffectiveness for such contracts.

Cash Flow Hedges of Commodities Risk

Our objectives in using commodities derivatives are to add stability to energy costs and to manage our exposure to fluctuations in natural gas prices. To accomplish this objective, we have historically used natural gas swap agreements as part of our commodities risk management strategy. These hedge agreements are used to exchange the difference between natural gas prices calculated by reference to an agreed-upon notional principal amount or natural gas quantity.

We had entered into natural gas swap agreements that effectively placed a fixed price for a specific quantity of natural gas. The agreements hedged against the increase in natural gas prices for the purchase of 420,000 MMBTU. The agreements matured on December 31, 2011.

The following table summarizes the fair value of our derivative instruments. See Note K for additional disclosures regarding the estimated fair values of our derivative instruments at December 31, 2013, and 2012.


			December 31, 2013						December 31, 2012
	Maturity Date		Contract/Notional Amount		Carrying Amount		Fair Value		Contract/Notional Amount		Carrying Amount		Fair Value

Interest rate cap agreement⁽¹⁾		2013	$	—	$	—	$	—	$	130 million	$	—	$	—

Interest rate cap agreement⁽¹⁾		2016	$	188 million	$	—	$	—	$	—	$	—	$	—

⁽¹⁾	Agreements limit the LIBOR floating interest rate base to 4%.

We have designated these contracts as qualified cash flow hedges. Accordingly, the effective portion of the gain or loss on the derivative instrument is reported as a component of other comprehensive income and recognized in earnings in the same period or periods during which the hedged transaction affects earnings.

The following table summarizes the effect of derivatives instruments on our income statements and our condensed consolidated statements of comprehensive income for the years ended December 31, 2013, 2012 and 2011.


	2013			2012			2011
Deferred gains (losses) from derivatives in OCI, beginning of period	$	(182	)	$	(409	)	$	(532	)
Gain (loss) recognized in OCI from derivative instruments		(82	)		—			123
Gain (loss) reclassified from Accumulated OCI		185			227			—

Deferred gains (losses) from derivatives in OCI, end of period	$	(79	)	$	(182	)	$	(409	)

- Definition

The entire disclosure for derivative instruments and hedging activities including, but not limited to, risk management strategies, non-hedging derivative instruments, assets, liabilities, revenue and expenses, and methodologies and assumptions used in determining the amounts.

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Reference 19: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=7476318&loc=d3e41638-113959

Reference 20: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4C

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624171-113959

+ Details

Equity-Based Compensation

12 Months Ended

Dec. 31, 2013

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Equity-Based Compensation

NOTE N—EQUITY-BASED COMPENSATION

During 2009, the board of directors of our then parent company, GGC USS Holdings, LLC, approved, and the parent company implemented, a management equity program (the “Equity Program”). The Equity Program granted Class C and Class D member units in the then parent company, GGC USS Holdings, LLC, to three members of executive management. As of December 31, 2013, all Class C and Class D equity units were vested.

The Class C units vested ratably over five years. These units have no exercise price and as such the fair value of the incentive units is equal to the fair value of the underlying equity units. The Class D units were fully vested upon grant in 2009. During 2013, the vesting of 210,333 Class C equity units was accelerated, resulting in a total vesting for the year of 420,667.

Even though the equity was granted at the former parent company level, we recognized compensation expense related to Class C equity incentive units of $109, $208 and $239 in the years ended December 31, 2013, 2012 and 2011, respectively. During 2013, no Class C equity incentive units were forfeited. In 2012, we recorded a reversal of previously recognized compensation expense of $11 associated with these units and cancelled the remaining unamortized expense of $109. During 2011, 867,625 Class C equity incentive units were forfeited resulting in a reversal of previously recognized compensation expense of $344 associated with these units and canceled the remaining unamortized expense of $476.

Our activity with respect to Class C equity incentive units for 2013, 2012, and 2011 was as follows:


	Number of Class C Units			Class C Unit Grant Date Weighted Average Fair Value
Unvested, December 31, 2010		2,418,834		$	0.52
Granted		—			—
Vested		(499,542	)	$	0.52
Forfeited		(867,625	)	$	0.52

Unvested, December 31, 2011		1,051,667		$	0.52
Granted		—			—
Vested		(420,667	)	$	0.52
Forfeited		(210,333	)	$	0.52

Unvested, December 31, 2012		420,667		$	0.52
Granted		—			—
Vested		(420,667	)	$	0.52
Forfeited		—			—

Unvested, December 31, 2013		—		$	—

The total fair value of equity incentive units vested for the years ended December 31, 2013, 2012 and 2011 was $0, $219 and $260, respectively.

Fair value of the underlying equity units is determined by utilizing the Black-Scholes pricing model and taking into consideration the rights and preferences of the underlying equity units.

The following table illustrates the assumptions used in the Black-Scholes pricing model:


Risk-free interest rate	1.87	%
Expected volatility	50	%
Expected term	4 years

Risk-free interest rate—This is an interpolated rate from the U.S. constant maturity treasury rate for a term corresponding to the time to liquidity event, as described below. An increase in the risk-free rate will increase compensation expense.

Expected volatility—This is a measure of the amount by which the price of various comparable companies’ common stock has fluctuated or is expected to fluctuate. Our common stock was not publicly-traded at the time of issuance. The comparable companies were selected by analyzing public companies in the industry based on various factors including, but not limited to, company size, financial data availability, active trading volume, and capital structure. An increase in the expected volatility will increase compensation expense.

Expected term—This is the period of time over which the underlying equity units are expected to remain outstanding. An increase in the expected term will increase compensation expense.

In July 2011, we adopted the U.S. Silica Holdings, Inc. 2011 Incentive Compensation Plan (the “2011 Plan”), which provides for grants of stock options, stock appreciation rights, restricted stock and other incentive-based awards.

As of December 31, 2013, there were a total of 1,231,540 options outstanding, 296,908 of which are exercisable, at a weighted-average exercise price of $14.30. The options vest on a graded vesting schedule and the related compensation expense is recognized over the vesting period of each separately vesting portion. We recognized $2.0 million, $2.2 million and $1.0 million of equity-based compensation expense related to these options during the years ended December 31, 2013, 2012 and 2011, respectively. As of December 31, 2013, there was $4.1 million of total unrecognized compensation expense related to these options, which is expected to be recognized over a weighted-average period of approximately 2.4 years.

Our activity with respect to stock options for the years ended December 31, 2013, 2012 and 2011 was as follows:


	Number of Shares			Range of Exercise Prices		Weighted Average Exercise Price		Fair Value
Unvested, July 8, 2011 (plan inception)		—			—		—		—
Granted		1,650,386		$	10.33 – 25.00	$	14.56	$	4.36
Exercised		—			—		—		—
Vested		—			—		—		—
Forfeited		(148,988	)		—	$	14.21	$	3.81

Unvested, December 31, 2011		1,501,398		$	10.33 – 25.00	$	14.60	$	3.74
Granted		572,847		$	10.57 – 24.00		14.15	$	5.68
Exercised		(9,528	)		10.33		10.33		4.67
Vested		—			—		—		—
Forfeited		(241,317	)		—		15.34		4.47

Unvested, December 31, 2012		1,823,400		$	10.33 – 25.00	$	14.38	$	5.04
Granted		140,000		$	20.03 – 24.59		22.48	$	10.03
Exercised		(551,165	)		10.33 – 25.00		14.41		4.35
Vested		—			—		—		—
Forfeited		(180,695	)		—		16.30		5.93

Unvested, December 31, 2013		1,231,540		$	10.33 – 25.00	$	15.01	$	5.39

The total intrinsic value of stock options exercised in 2013 was $5.9 million. Cash received from options exercised in 2013 was $7.9 million. The actual tax benefit realized for the tax deductions from option exercises in 2013 totaled $2.3 million.

In calculating the compensation expense for options granted, we have estimated the fair value of each grant issued through December 31, 2013 using the Black-Scholes option-pricing model. The fair value of stock options granted have been calculated based on the stock price on the date of the option grant, the exercise price of the option and the following assumptions, which are evaluated and revised, as necessary, to reflect market conditions and experience. These assumptions are the weighted-average of the assumptions used for all grants which occurred during the respective fiscal year.

The following table illustrates the assumptions used in the Black-Scholes pricing model for options granted during the respective fiscal year:


	2013			2012
Risk-free interest rate		1.03 – 1.31	%		0.83 – 1.05	%
Expected volatility		45	%		45	%
Expected term		6.25 years			6.25 years
Expected dividend yield		0	%		0	%
Expected forfeiture yield		0	%		0	%

Risk-free interest rate—This is an interpolated rate from the U.S. constant maturity treasury rate for a term corresponding to the expected term, as described below. An increase in the risk-free rate will increase compensation expense.

Expected volatility—This is a measure of the amount by which the price of various comparable companies’ common stock has fluctuated or is expected to fluctuate, as our common stock has not been publicly-traded for an adequate period of time. The comparable companies were selected by analyzing public companies in the industry based on various factors including, but not limited to, company size, financial data availability, active trading volume, and capital structure. An increase in the expected volatility will increase compensation expense.

Expected term—This is the period of time over which the options are expected to remain outstanding. An increase in the expected term will increase compensation expense. The computation of the expected term is based on the simplified method as our stock options are standard options and we have little recent history of exercise data. Under the simplified method, the expected term is presumed to be the mid-point between the average vesting date and the end of the contractual term.

Since January 31, 2012, the date of our initial public offering, we declared a special dividend of $0.50 per share on December 10, 2012 and three quarterly dividends of $0.125 per share during 2013. Options issued in 2013 all occurred early in the year before dividends were consistently declared. As a result, the dividend yield assumptions for those and all prior options issued was 0.00%. We will continue to evaluate this assumption as we develop a dividend history and new options are issued.

Our expected forfeiture rate is the estimated percentage of options granted that are expected to be forfeited or cancelled on an annual basis before becoming fully vested. We have assumed that there will be no forfeitures due to the fact that we do not have adequate historical forfeiture data on which to base the assumption.

As of December 31, 2013, there were a total of 228,403 shares of restricted stock. The restricted stock vests on a graded vesting schedule and the related compensation expense is recognized over the vesting period of each separately vesting portion. The fair value of the restricted stock awards is equal to the market price of our stock at date of grant. We recognized $976 of equity-based compensation expense related to these restricted stock shares during the year ended December 31, 2013. As of December 31, 2013, there was $2.1 million of total unrecognized compensation expense related to these restricted stock shares, which is expected to be recognized over a period of 2.3 years.


	Number of Shares			Grant Date Weighted Average Fair Value
Unvested, December 31, 2012		70,000		$	15.58
Granted		180,069			22.58
Vested		(21,666	)		17.11
Forfeited		—			—

Unvested, December 31, 2013		228,403		$	20.95

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References+ Details

Leases

12 Months Ended

Dec. 31, 2013

Leases [Abstract]

Leases

NOTE O—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 December 31, 2013 are as follows:


2014		23,722
2015		21,915
2016		19,726
2017		17,614
2018		16,326
Thereafter		36,125

Total future lease commitments	$	135,428

Expense related to operating leases and rental agreements for the years ended December 31, 2013, 2012 and 2011 totaled approximately $16.3 million, $11.9 million and $6.5 million, respectively.

As of December 31, 2013 and 2012, we have no obligation under a capital lease.

In general, the above leases include renewal options and provide that we pay for all utilities, insurance, taxes and maintenance.

- Definition

The entire disclosure for lessee entity's leasing arrangements including, but not limited to, all of the following: (a.) The basis on which contingent rental payments are determined, (b.) The existence and terms of renewal or purchase options and escalation clauses, (c.) Restrictions imposed by lease agreements, such as those concerning dividends, additional debt, and further leasing.

+ References+ Details

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2013
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	NOTE P—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. U.S. Silica was named as a defendant in three claims filed during the year ended December 31, 2013, two filed in 2012 and three filed in 2011. U.S. Silica has been named as a defendant in similar suits since 1975. As of December 31, 2013, 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 numerous 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 policies receiving $5.1 million from the parties involved. 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 indemnity agreement and an estimate of future recoveries under insurance in other assets on our consolidated balance sheets. As of December 31, 2013 and 2012, other noncurrent assets included $313 and $247, respectively, for insurance for third-party products liability claims and other long-term obligations included $1.6 million and $1.3 million, respectively, in third-party products claims liability. Based on decreases in the actual claims filed during the periods along with decreases in the estimated future product liability claims and their related costs, as well as the aforementioned settlement, we recorded pre-tax adjustments to selling, general and administrative expenses related to silica claims (including a $0.5 million loss in 2013, a $3.4 million gain in 2012, and a $2.6 million gain in 2011).

- Definition

The entire disclosure for commitments and contingencies.

+ References+ Details

Income Taxes

12 Months Ended

Dec. 31, 2013

Income Tax Disclosure [Abstract]

Income Taxes

NOTE Q—INCOME TAXES

We evaluate our deferred tax assets periodically to determine if valuation allowances are required. Ultimately, the realization of deferred tax assets is dependent upon generation of future taxable income during those periods in which temporary differences become deductible and/or credits can be utilized. To this end, management considers the level of historical taxable income, the scheduled reversal of deferred tax liabilities, tax-planning strategies and projected future taxable income. Based on these considerations, and the carry-forward availability of a portion of the deferred tax assets, management believes it is more likely than not that we will realize the benefit of the deferred tax assets.

The (expense) benefit for income taxes consisted of the following for the years ended December 31, 2013, 2012 and 2011.


	Years Ended December 31,
	2013			2012			2011
Current:
Federal	$	(20,819	)	$	(22,165	)	$	(3,222	)
State		(1,831	)		(6,237	)		(51	)

		(22,650	)		(28,402	)		(3,273	)

Deferred:
Federal		1,453			(3,645	)		(2,624	)
State		436			1,396			(1,265	)

		1,889			(2,249	)		(3,889	)

Income tax expense	$	(20,761	)	$	(30,651	)	$	(7,162	)

Deferred tax assets and liabilities are recognized for the estimated future tax effects, based on enacted tax laws, of temporary differences between the values of assets and liabilities recorded for financial reporting and for tax purposes and of net operating loss and other carry forwards.

The tax effects of the types of temporary differences and carry forwards that gave rise to deferred tax assets and liabilities at December 31, 2013 and 2012 consisted of the following:


	At December 31,
	2013			2012
Gross deferred tax assets:
State tax credits and net operating loss carry forward	$	1,007		$	924
Pension and post-retirement benefit costs		15,579			22,427
Alternative minimum tax credit carry forward		22,528			25,889
Property, plant and equipment		6,109			5,113
Accrued expenses		3,818			2,272
Inventories		5,863			1,689
Third-party products liability		674			531
Stock-based compensation expense		1,306			1,262
Other		5,502			6,019

Total deferred tax assets	$	62,386		$	66,126

Gross deferred tax liabilities:
Land and mineral property basis difference	$	(61,366	)	$	(60,954	)
Fixed assets and depreciation		(47,016	)		(46,396	)
Intangible assets		(6,788	)		(6,957	)
Other		(797	)		(822	)

Total deferred tax liabilities		(115,967	)		(115,129	)

Net deferred tax liabilities		(53,581	)		(49,003	)
Less: Net current deferred tax assets		(17,737	)		(10,108	)

Net long-term deferred tax liabilities	$	(71,318	)	$	(59,111	)

At December 31, 2013 and 2012, we have an alternative minimum tax credit carry forward at December 31, 2013 and 2012 of approximately $22.5 million and $25.9 million, respectively. The credit carry forward may be carried forward indefinitely to offset any excess of regular tax liability over alternative minimum tax liability subject to certain limitations.

Ultimately, the realization of deferred tax assets is dependent upon generation of future taxable income during those periods in which temporary differences become deductible and/or credits can be utilized. To this end, management considers the level of historical taxable income, the scheduled reversal of deferred tax liabilities, tax-planning strategies and projected future taxable income. Based on these considerations, and the carry-forward availability of a portion of the deferred tax assets, management believes it is more likely than not that we will realize the benefit of the deferred tax assets.

At the end of each reporting period as presented, there were no material amounts of interest and penalties recognized in the statement of operations or balance sheets. We have no material unrecognized tax benefits or any known material tax contingencies at December 31, 2013 or December 31, 2012 and does not expect this to change significantly within the next twelve months. Tax returns filed with the IRS for the years 2010 through 2012 along with tax returns filed with numerous state entities remain subject to examination.

Excess tax benefits from equity-based compensation are credited to stockholders’ equity. The excess tax benefits credited to stockholders’ equity were $1.4 million for the year ended December 31, 2013. There were no excess tax benefits for the years ended December 31, 2012 and 2011.

The effective income tax rate on pretax earnings differed from the U.S. federal statutory rate for the years ended December 31, 2013, 2012 and 2011 for the following reasons:


	Years Ended December 31,
	2013			2012			2011
(Expense) benefit computed at U.S. federal statutory rate		(35.0	)%		(35.0	)%		(35.0	)%
Decrease (increase) resulting from:
Percentage depletion		11.0			9.9			17.5
Prior year tax return reconciliation		1.9			(0.5	)		0.4
State income taxes, net of federal benefit		(2.4	)		(2.7	)		(1.6	)
Domestic production deduction		2.4			0.7			—
Medicare Part D subsidy		—			—			(0.1	)
Equity-based compensation		—			(0.1	)		(0.2	)
Other, net		0.5			(0.2	)		(0.1	)

Income tax (expense) benefit		(21.6	)%		(27.9	)%		(19.1	)%

The largest permanent item in computing both our effective tax rate and taxable income is the deduction allowed for statutory depletion. The deduction for statutory depletion does not necessarily change proportionately to changes in income before income taxes.

We are evaluating the potential impact of the final Treasury regulations released on September 13, 2013 concerning amounts paid to acquire, produce or improve tangible property and recovery of basis upon disposition. We are determining whether or not any changes in accounting method will be required and if they will result in a material impact to our financial statements. At this time, we do not anticipate there being a material impact.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References+ Details

Pension and Post-Retirement Benefits

12 Months Ended

Dec. 31, 2013

Compensation And Retirement Disclosure [Abstract]

Pension and Post-Retirement Benefits

NOTE R—PENSION AND POST-RETIREMENT BENEFITS

We maintain a single-employer noncontributory defined benefit pension plan covering certain employees. There have been no new entrants to the plan since May 2009 when the plan was frozen to all new employees. The plan provides benefits based on each covered employee’s years of qualifying service. Our funding policy is to contribute amounts within the range of the minimum required and maximum deductible contributions for the plan consistent with a goal of appropriate minimization of the unfunded projected benefit obligation. The pension plan uses a benefit level per year of service for covered hourly employees and a final average pay method for covered salaried employees. The plan uses the projected unit credit cost method to determine the actuarial valuation.

We employ a total rate of return investment approach whereby a mix of equities and fixed income investments are used to maximize the long-term return of plan assets for a prudent level of risk. Risk tolerance is established through careful consideration of plan liabilities, plan funded status, and corporate financial condition. The investment portfolio contains a diversified blend of equity and fixed-income investments. Furthermore, equity investments are diversified across U.S. and non-U.S. stocks, as well as growth, value and small and large capitalizations. Investment risk is measured and monitored on an ongoing basis through quarterly investment portfolio reviews, annual liability measurements, and periodic asset/liability studies.

We employ a building block approach in determining the long-term rate of return for plan assets. Historical markets are studied and long-term historical relationships between equities and fixed-income are preserved consistent with the widely accepted capital market principle that assets with higher volatility generate a greater return over the long run. Current market factors such as inflation and interest rates are evaluated before long-term capital market assumptions are determined. The long-term portfolio return is established via a building block approach with proper consideration of diversification and rebalancing. Peer data and historical returns are reviewed to check for reasonability and appropriateness.

In addition, we provide defined benefit post-retirement healthcare and life insurance benefits to some employees. Covered employees become eligible for these benefits at retirement after meeting minimum age and service requirements. The projected future cost of providing post-retirement benefits, such as healthcare and life insurance, is recognized as an expense as employees render services.

We contribute to a Voluntary Employees’ Beneficiary Association trust that will be used to partially fund health care benefits for future retirees. Benefits are funded to the extent contributions are tax deductible, which under current legislation is limited. In general, retiree health benefits are paid as covered expenses are incurred.

Net pension benefit cost consisted of the following for the years ended December 31, 2013, 2012 and 2011:


	Years Ended December 31,
	2013			2012			2011
Service cost—benefits earned during the period	$	1,280		$	1,118		$	1,145
Interest cost		4,198			4,734			4,755
Expected return on plan assets		(5,061	)		(5,381	)		(4,817	)
Net amortization and deferral		1,904			1,105			595

Net pension benefit costs	$	2,321		$	1,576		$	1,678

Net post-retirement cost consisted of the following for the years ended December 31, 2013, 2012 and 2011:


	Years Ended December 31,
	2013			2012			2011
Service cost—benefits earned during the period	$	193		$	197		$	185
Interest cost		947			1,163			1,161
Expected return on plan assets		(4	)		(4	)		(5	)
Net amortization and deferral		87			177			—

Net post-retirement costs	$	1,223		$	1,533		$	1,341

The changes in benefit obligations and plan assets, as well as the funded status of our pension and post-retirement plans at December 31, 2013 and 2012 were as follows:


	Pension Benefits						Post-retirement Benefits
	2013			2012			2013			2012
Benefit obligation at January 1,	$	107,619		$	100,083		$	25,717		$	26,528
Service cost		1,280			1,118			193			197
Interest cost		4,198			4,734			947			1,163
Actuarial gain (loss)		(8,071	)		10,255			(3,933	)		(1,087	)
Benefits paid		(5,749	)		(9,238	)		(1,102	)		(1,529	)
Amendments		551			667			—			—
Other		—			—			439			445

Benefit obligation at December 31,	$	99,828		$	107,619		$	22,261		$	25,717

Fair value of plan assets at January 1,	$	80,850		$	74,596		$	54		$	54
Actual return on plan assets		7,986			10,711			8			—
Employer contributions		2,280			4,781			652			1,084
Benefits paid		(5,749	)		(9,238	)		(1,102	)		(1,529	)
Other		—			—			439			445

Fair value of plan assets at December 31,	$	85,367		$	80,850		$	51		$	54

Plan assets less than benefit obligations at December 31 recognized as liability for pension and other post-retirement benefits	$	(14,461	)	$	(26,768	)	$	(22,210	)	$	(25,664	)

The accumulated benefit obligation for the defined benefit pension plans, which excludes the assumption of future salary increases, totaled $99.4 million and $107.0 million at December 31, 2013 and 2012, respectively.

The amendments in 2012 reflect plan changes including increases in the benefit multiplier for certain participants as well as the reduction of certain benefits to estimated highly compensated salary participants.

We also sponsor unfunded, nonqualified pension plans. The projected benefit obligation, accumulated benefit obligation and fair value of plan assets for these plans were $1.6 million, $1.6 million and $0 at December 31, 2013 and $1.7 million, $1.7 million and $0 million at December 31, 2012.

Future estimated annual benefit payments for pension and post-retirement benefit obligations as of December 31, 2013 are as follows:


	Benefits
			Post-retirement
	Pension		Before Medicare Subsidy		After Medicare Subsidy
2014		6,104		1,524		1,354
2015		6,295		1,550		1,369
2016		6,514		1,596		1,404
2017		6,802		1,696		1,495
2018		7,039		1,722		1,513
2019-2022		36,711		9,080		7,960

Our best estimate of expected contributions to the pension and post-retirement medical benefit plans for the 2014 fiscal year are $4.6 million and $1.4 million, respectively.

The amounts in accumulated other comprehensive income expected to be recognized as components of net periodic benefit cost during the 2014 fiscal year are as follows:


	Benefits
	Pension		Post-retirement		Total
Net actuarial loss	$	485	$	—	$	485
Prior service cost		201		—		201

	$	686	$	—	$	686

The total amounts in accumulated other comprehensive income related to net actuarial loss and prior service costs, net of tax, as of December 31, 2013 were $3.4 and $2.3 million, respectively.

The following weighted-average assumptions were used to determine our obligations under the plans:


	Pension Benefits						Post-retirement Benefits
	2013			2012			2013			2012
Discount rate		4.8	%		4.00	%		4.8	%		4.00	%
Long-term rate of compensation increase		3.5	%		3.50	%		N/A			N/A
Long-term rate of return on plan assets		7.5	%		8.00	%		7.5	%		8.00	%
Health care cost trend rate:
Pre-65 initial rate/ultimate rate		N/A			N/A			8%/5	%		8.5%/5	%
Pre-65 ultimate year		N/A			N/A			0			0
Post-65 initial rate/ultimate rate		N/A			N/A			7.3%/5	%		7.5%/5	%
Post-65 ultimate year		N/A			N/A			2021			2020

The discount rate reflects the expected long-term rates of return with maturities comparable to payments for the plan obligations utilizing Aon Hewitt’s AA Only Above Medium Curve, rounded down to the next 0.05%.

Assumed health care cost trend rates have a significant effect on the amounts reported for the health care plans. A one-percentage-point change in assumed health care cost trend rates would have the following effects:


	One-Percentage-Point
	Increase		Decrease
Effect on total of service and interest cost	$	145	$	(122	)
Effect on post-retirement benefit obligation		2,535		(2,163	)

The major investment categories and their relative percentage of the fair value of total plan assets as invested at December 31, 2013 and 2012 were as follows:


	Pension Benefits						Post-retirement Benefits
	2013			2012			2013			2012
Equity securities		57.4	%		59.9	%		59.0	%		58.7	%
Debt securities		36.6	%		38.6	%		29.5	%		39.2	%
Cash		6.0	%		1.5	%		11.5	%		2.1	%

The fair values of the pension plan assets at December 31, 2013, by asset category, are as follows:


	Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	5,067	$	—	$	—	$	5,067
Mutual funds:
Diversified emerging markets		7,753		—		—		7,753
Foreign large blend		13,851		—		—		13,851
Large-cap blend		17,804		—		—		17,804
Long-term bonds		31,230		—		—		31,230
Mid-cap blend		5,807		—		—		5,807
Real estate		3,776		—		—		3,776
Insurance policies		—		—		79		79

Net asset	$	85,288	$	—	$	79	$	85,367

The fair values of the pension plan assets at December 31, 2012, by asset category, are as follows:


	Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	1,208	$	—	$	—	$	1,208
Mutual funds:
Diversified emerging markets		8,186		—		—		8,186
Foreign large blend		13,827		—		—		13,827
Large-cap blend		16,666		—		—		16,666
Long-term bonds		31,198		—		—		31,198
Mid-cap blend		5,650		—		—		5,650
Real estate		4,026		—		—		4,026
Insurance policies		—		—		89		89

Net asset	$	80,761		—	$	89	$	80,850

We contribute to three multiemployer defined benefit pension plans under the terms of collective-bargaining agreements for union-represented employees. A multiemployer plan is subject to collective bargaining for employees of two or more unrelated companies. These plans allow multiple employers to pool their pension resources and realize efficiencies associated with the daily administration of the plan. Multiemployer plans are generally governed by a board of trustees composed of management and labor representatives and are funded through employer contributions. However, in most cases, management is not directly represented.

The risks of participating in multiemployer plans differ from single employer plans as follows: 1) assets contributed to a multiemployer plan by one employer may be used to provide benefits to employees of other participating employers, 2) if a participating employer stops contributing to the plan, the unfunded obligations of the plan may be borne by the remaining participating employers, and 3) if we cease to have an obligation to contribute to one or more of the multiemployer plans to which we contribute, we may be required to pay those plans an amount based on the underfunded status of the plan, referred to as a withdrawal liability.

A summary of each multiemployer pension plan for which we participate is presented below:

Pension

Fund

EIN/ Pension
Plan No.

Pension Protection Act
Zone Status⁽¹⁾

FIP/RP Status
Pending/
Implemented

Company
Contributions

Surcharge
Imposed

Expiration
Date of
CBA

2013

2012

2013

2012

2011

LIUNA

52-6074345/001

Red

Yes

124

123

116

Yes

5/31/2014

IUOE

36-6052390/001

Green

7/31/2015

CSSS⁽²⁾

36-6044243/001

Red

Yes

⁽¹⁾	The Pension Protection Act of 2006 defines the zone status as follows: green—healthy, yellow—endangered, orange—seriously endangered and red—critical.

⁽²⁾	In 2011, we withdrew from the Central States, Southeast and Southwest Areas Pension Plan. The withdrawal liability of $1.0 million will be paid in monthly installments of $4 until 2031.

Our contributions to individual multiemployer pension funds did not exceed 5% of the fund’s total contributions in any of the three years ended December 31, 2013. Additionally, our contributions to multiemployer postretirement benefit plans were immaterial for all periods presented in the accompanying consolidated financial statements.

We also sponsor a defined contribution plan covering certain employees. We contribute to the plan in two ways. For certain employees not covered by the defined benefit plan, we make a contribution equal to 4% of their salary. We also contribute an employee match of 25 cents, based on financial performance, for each dollar contributed by an employee, up to 8% of their earnings. For certain employees, we make a profit sharing match up to 75 cents, based on financial performance, for each dollar contributed up to 8% of their earnings. Finally, for some employees, we make a catch-up match of 25 cents for each dollar of catch-up contributions. Contributions were $1.7 million, $1.4 million and $1.0 million for the years ended December, 31, 2013, 2012 and 2011, respectively.

Obligations Under Guarantees	12 Months Ended
Obligations Under Guarantees	Dec. 31, 2013
Guarantees [Abstract]
Obligations Under Guarantees	NOTE S—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 December 31, 2013, Travelers had $7.7 million in bonds outstanding for us. The majority of these bonds ($7.6 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. We have indemnified Safeco Insurance Company of America (“Safeco”) against any loss Safeco may incur in the event that holders of surety bonds, issued on behalf of us by Safeco, execute the bonds. As of December 31, 2013, Safeco had $513 in bonds outstanding for us. These are all reclamation bonds. 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.

Related Party Transactions	12 Months Ended
Related Party Transactions	Dec. 31, 2013
Related Party Transactions [Abstract]
Related Party Transactions	NOTE T—RELATED PARTY TRANSACTIONS Advisory Agreement In connection with our acquisition by Golden Gate Capital, we entered into an Advisory Agreement with Golden Gate Capital whereby Golden Gate Capital agreed to provide business and organizational strategy and financial and advisory services. Such services included support and assistance to management with respect to negotiating and analyzing acquisitions and divestitures, negotiating and analyzing financing alternatives, preparing financial projections, monitoring compliance with financing agreements, marketing functions and searching for and hiring management personnel. As compensation for these services, we agreed to pay Golden Gate Capital (1) an annual advisory fee in the aggregate amount equal to $1.25 million, payable quarterly in arrears, and (2) a transaction fee of 1.25% of the aggregate value of each transaction resulting in a change in control of GGC Holdings or its subsidiaries, along with each acquisition, divestiture, recapitalization and financing. In addition to the fees described above, we also reimbursed Golden Gate Capital for all out-of-pocket costs incurred by Golden Gate Capital in connection with its activities under the Advisory Agreement, and indemnified Golden Gate Capital from and against all losses, claims, damages and liabilities related to the performance of its duties under the Advisory Agreement. On February 6, 2012, we paid $8.0 million to Golden Gate Capital to terminate the Advisory Agreement. The $8.0 million termination fee was accrued for at December 31, 2011 and no additional expense has been recognized during the year ended December 31, 2012. Advisory fees paid to Golden Gate Capital under the Advisory Agreement in 2011 were $1.3 million. These expenses are included in other operating expenses and presented as advisory fees to parent within our income statements. Promissory Note On December 22, 2010, we entered into a $15.0 million promissory note with our former parent, GGC USS Holdings, LLC. The note provided working capital for a new subsidiary and was scheduled to mature on December 22, 2015. The note bore interest at 10%. Outstanding principal and interest under the note were payable upon demand, but no later than the maturity date. Upon sole election by GGC Holdings, any unpaid interest could be paid in cash on each December 22 of each year until the maturity date. As of and for the year ended December 31, 2011, interest on the note is recorded in interest expense in the Income Statements and any unpaid interest is included in accrued interest on the Balance Sheet. On January 31, 2012, simultaneously with the IPO, GGC Holdings contributed to us all of the stock of GGC RCS Holdings, Inc. and converted the $15.0 million promissory note, including $1.7 million of accrued interest, to equity. As of December, 31, 2013, GGC USS Holdings, LLC held no interest in U.S. Silica after divesting its ownership interest in U.S. Silica during 2013.

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

+ References+ Details

Segment Reporting

12 Months Ended

Dec. 31, 2013

Segment Reporting [Abstract]

Segment Reporting

NOTE U—SEGMENT REPORTING

Our business is organized into two reportable segments, Oil & Gas Proppants and Industrial & Specialty Products, based on end markets. The reportable segments are consistent with how management views the markets that we serve and the financial information reviewed by the chief operating decision maker. We manage our Oil & Gas Proppants and Industrial & Specialty Products businesses as components of an enterprise for which separate information is available and is evaluated regularly by the chief operating decision maker in deciding how to allocate resources and assess performance.

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 its 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 included in Note B.

In the Oil & Gas Proppants segment, we serve the oil and gas recovery market 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 natural gas and oil 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 years ended December 31, 2013, 2012 and 2011:


	Years Ended December 31,
	2013			2012			2011

Sales:
Oil and gas proppants	$	347,439		$	243,765		$	107,074
Industrial and specialty products		198,546			198,156			188,522

Total sales		545,985			441,921			295,596
Segment contribution margin:
Oil and gas proppants		145,916			140,070			67,590
Industrial and specialty products		56,983			53,601			53,013

Total segment contribution margin		202,899			193,671			120,603
Operating activities excluded from segment cost of goods sold		(5,481	)		(8,285	)		(6,203	)
Selling, general and administrative		(49,759	)		(41,299	)		(23,348	)
Advisory fees to parent		—			—			(9,250	)
Depreciation, depletion and amortization		(36,418	)		(25,099	)		(20,999	)
Interest expense		(15,341	)		(13,795	)		(18,407	)
Early extinguishment of debt		(480	)		—			(6,043	)
Other income, net, including interest income		597			4,612			1,062

Income (loss) before income taxes	$	96,017		$	109,805		$	37,415

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. No customer exceeded 10% or more of net sales in any of the periods presented.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

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+ Details

Unaudited Supplementary Data

12 Months Ended

Dec. 31, 2013

Text Block [Abstract]

Unaudited Supplementary Data

NOTE V—UNAUDITED SUPPLEMENTARY DATA

The following table sets forth our unaudited quarterly consolidated statements of operations for each of the last four quarters ended December 31, 2013 and 2012. This unaudited quarterly information has been prepared on the same basis as our annual audited financial statements and includes all adjustments, consisting only of normal recurring adjustments that are necessary to present fairly the financial information for the fiscal quarters presented.


	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
2013:
Sales	$	122,311		$	129,828		$	144,372		$	149,474
Costs of goods sold		74,412			80,297			90,983			102,875
Operating expenses
Selling, general and administrative		12,404			10,099			12,800			14,456
Depreciation, depletion and amortization		8,278			8,890			9,152			10,098

		20,682			18,989			21,952			24,554

Operating income		27,217			30,542			31,437			22,045
Other (expense) income
Interest expense		(3,576	)		(3,535	)		(4,144	)		(4,086	)
Early extinguishment of debt		—			—			(480	)		—
Other income, net, including interest income		122			63			260			152

		(3,454	)		(3,472	)		(4,364	)		(3,934	)

Income before income taxes		23,763			27,070			27,073			18,111
Income tax expense		(6,486	)		(6,878	)		(5,739	)		(1,658	)

Net income	$	17,277		$	20,192		$	21,334		$	16,453

Earnings per share, basic	$	0.33		$	0.38		$	0.40		$	0.31
Earnings per share, diluted	$	0.32		$	0.38		$	0.40		$	0.31
Weighted average common shares outstanding (in thousands), basic		52,946			52,948			53,103			53,035
Weighted average common shares outstanding (in thousands), diluted		52,211			53,227			53,429			53,409

	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
2012:
Sales	$	102,591		$	104,599		$	115,885		$	118,846
Costs of goods sold		56,921			58,920			69,706			70,988
Operating expenses
Selling, general and administrative		9,904			9,718			10,135			11,542
Depreciation, depletion and amortization		5,978			5,974			5,968			7,179

		15,882			15,692			16,103			18,721

Operating income		29,788			29,987			30,076			29,137
Other (expense) income
Interest expense		(3,797	)		(3,428	)		(3,326	)		(3,244	)
Other income, net, including interest income		154			179			348			3,931

		(3,643	)		(3,249	)		(2,978	)		687

Income before income taxes		26,145			26,738			27,098			29,824
Income tax (expense) benefit		(7,032	)		(7,287	)		(8,302	)		(8,030	)

Net income	$	19,113		$	19,451		$	18,796		$	21,794

Earnings per share, basis and diluted	$	0.37		$	0.37		$	0.36		$	0.41
Weighted average common shares outstanding (in thousands), basic		51,939			52,440			52,873			52,891
Weighted average common shares outstanding (in thousands), diluted		52,031			52,505			52,887			52,963

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2013
Subsequent Events [Abstract]
Subsequent Events	NOTE W—SUBSEQUENT EVENTS On January 3, 2014, we paid a cash dividend of $0.125 per share to common stockholders of record on December 16, 2013, as had been declared by our Board of Directors on October 24, 2013. On January 29, 2014, Travelers Casualty and Surety Company of America released a letter of credit it previously held as collateral for surety bonds in the amount of $4.4 million. A corresponding amount of liquidity, therefore, became available under the Revolver as of that date. 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, payable on April 1, 2014.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2013

Accounting Policies [Abstract]

Basis of Presentation and Consolidation

Basis of Presentation and Consolidation

Use of Estimates and Assumptions

Use of Estimates and Assumptions

Revenue Recognition

Revenue Recognition

Cash and Cash Equivalents

Cash and Cash Equivalents

Accounts Receivable

Accounts Receivable

Inventories

Inventories

Property, Plant and Mine Development

Property, Plant and Mine Development

Property and equipment

Mine exploration and development

Mine reclamation costs


	2013		2012
Beginning balance	$	6,659	$	9,504
Payments		—		—
Accretion		456		658
Revisions of prior estimates		2,263		(3,503	)

Ending balance	$	9,378	$	6,659

Goodwill and Other Intangible Assets and Related Impairment

Goodwill and Other Intangible Assets and Related Impairment

Debt Issuance Costs

Debt Issuance Costs

Transportation Revenue and Expense

Transportation Revenue and Expense

Environmental Costs

Environmental Costs

Self-Insurance

Self-Insurance

Equity-based Compensation

Equity-based Compensation

Income Taxes

Income Taxes

Net Income per Common Share

Net Income per Common Share

Comprehensive Income

Comprehensive Income

Short-Term Investments

Short-Term Investments

Financial Instruments

Financial Instruments

Recently Adopted Accounting Pronouncements

Recently Adopted Accounting Pronouncements

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2013

Accounting Policies [Abstract]

Changes in Asset Retirement Obligation

Changes in the asset retirement obligation are as follows:


	2013		2012
Beginning balance	$	6,659	$	9,504
Payments		—		—
Accretion		456		658
Revisions of prior estimates		2,263		(3,503	)

Ending balance	$	9,378	$	6,659

Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2013

Earnings Per Share [Abstract]

Schedule of Basic and Diluted Earnings Per Share


	For the Year Ended December 31,
	2013			2012			2011
Net income	$	75,256		$	79,154		$	30,253
Less: net income allocated to outstanding restricted stockholders		(175	)		(105	)		—

Net income allocated to common stockholders	$	75,081		$	79,049		$	30,253


Weighted-average common stock
Outstanding		53,035			52,592			50,000
Outstanding assuming dilution		53,409			52,641			50,006

Capital Structure and Accumulated Comprehensive Income (Tables)

12 Months Ended

Dec. 31, 2013

Equity [Abstract]

Changes in Accumulated Other Comprehensive Income

The following table presents the changes in accumulated other comprehensive income by component during the year ended December 31, 2013:


	For the Year Ended December 31, 2013
	Unrealized gain/(loss) on cash flow hedges			Unrealized gain/(loss) on short-term investments			Pension and other post- retirement benefits liability			Total
Beginning Balance	$	(182	)	$	—		$	(13,993	)	$	(14,175	)
Other comprehensive income (loss) before reclassifications		(82	)		(27	)		8,844			8,735
Amounts reclassed from accumulated other comprehensive income		185			—			1,238			1,423

Ending Balance	$	(79	)	$	(27	)	$	(3,911	)	$	(4,017	)

Reclassifications Out of Accumulated Other Comprehensive Income (Loss)

The following table presents the reclassifications out of accumulated other comprehensive income (loss) during the year ended December 31, 2013:


Details about accumulated other comprehensive income	Amount reclassified from accumulated other comprehensive income			Affected line item in the statement of operations
Gains and losses on cash flow hedges
Interest rate contracts	$	304			Interest expense
		(119	)		Tax expense

	$	185			Net of tax

Amortization of postretirement benefits liability
Actuarial gains/(losses)	$	1,933			⁽¹	⁾
Prior service cost		92			⁽¹	⁾

	$	2,025			Total before tax
		(787	)		Tax expense

		1,238			Net of tax

Total reclassifications for the period	$	1,423			Net of tax

⁽¹⁾	These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see Note R).

Accounts Receivable (Tables)

12 Months Ended

Dec. 31, 2013

Receivables [Abstract]

Schedule of Accounts Receivable

At December 31, 2013 and 2012, accounts receivable consisted of the following:


	At December 31,
	2013			2012
Trade receivables	$	76,223		$	56,519
Less: Allowance for doubtful accounts		(2,376	)		(1,053	)

Net trade receivables		73,847			55,466
Other receivables		1,360			4,098

Total accounts receivable	$	75,207		$	59,564

Property, Plant and Mine Development (Tables)

12 Months Ended

Dec. 31, 2013

Property Plant And Equipment [Abstract]

Schedule of Property, Plant and Mine Development

At December 31, 2013 and 2012, property, plant and mine development consisted of the following:


	At December 31,
	2013			2012
Mining property and mine development	$	164,609		$	163,538
Asset retirement cost		7,275			5,124
Land		25,738			24,795
Land improvements		31,093			27,604
Buildings		36,311			31,558
Machinery and equipment		263,304			221,139
Furniture and fixtures		1,131			915
Construction-in-progress		25,974			18,049

		555,435			492,722
Accumulated depletion, depreciation and amortization		(113,319	)		(78,504	)

Total property, plant and mine development, net	$	442,116		$	414,218

Accrued Liabilities (Tables)

12 Months Ended

Dec. 31, 2013

Payables And Accruals [Abstract]

Schedule of Accrued Liabilities

At December 31, 2013 and 2012, accrued liabilities consisted of the following:


	At December 31,
	2013		2012

Accrued salaries and wages	$	2,411	$	2,939
Accrued vacation liability		2,396		2,397
Current portion of liability for pension and post-retirement benefits		1,428		1,413
Accrued healthcare liability		1,662		1,278
Other accrued liabilities		2,926		1,454

Total accrued liabilities	$	10,823	$	9,481

Debt (Tables)

12 Months Ended

Dec. 31, 2013

Debt Disclosure [Abstract]

Schedule of Debt

At December 31, 2013 and 2012, debt consisted of the following:


	December 31, 2013			December 31, 2012
Revolving line-of-credit:	$	—	⁽¹⁾	$	—	⁽²⁾
⁽¹⁾ Revolver expiring July 23, 2018 (4.75% at December 31, 2013)
⁽²⁾ Revolver expiring October 31, 2016 (5.0% at December 31, 2012); replaced by ⁽¹⁾on July 23, 2013
Senior secured credit facility:		371,451			255,425
Term loan facility—final maturity July 23, 2020 (4% at December 31, 2013 and 4.75% at December 31, 2012), net of unamortized original issue discount of $1,674 and $675, respectively

Total debt		371,451			255,425
Less: current portion		(3,488	)		(2,433	)

Total long-term portion of debt	$	367,963		$	252,992

Schedule of Contractual Maturities of Debt

At December 31, 2013, contractual maturities of long-term debt are as follows:


2014		3,488
2015		3,490
2016		3,493
2017		3,495
2018		3,499
Thereafter		353,986

	$	371,451

Fair Value Accounting (Tables)

12 Months Ended

Dec. 31, 2013

Fair Value Disclosures [Abstract]

Schedule of Measure at Fair Value on Recurring Basis


	December 31, 2013						December 31, 2012
	Level 1		Level 2		Total		Level 1		Level 2		Total
Short-term investments	$	622	$	74,358	$	74,980	$	—	$	—	$	—
Interest rate derivatives		—		109		109		—		—		—

Net asset	$	622	$	74,467	$	75,089	$	—	$	—	$	—

Short-Term Investments (Tables)

12 Months Ended

Dec. 31, 2013

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 December 31, 2013:


	Aggregate Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Money market mutual funds	$	622	$	—	$	—		$	622
Fixed income securities:
Certificates of deposit		25,218		—		(34	)		25,184
Commercial paper		15,168		4		(1	)		15,171
Corporate notes and bonds		9,495		—		(9	)		9,486
Government agencies		13,979		6		—			13,985
U.S. Treasuries		4,828		—		(10	)		4,818
Variable Rate Demand Obligations		5,714		—		—			5,714

Total available-for-sale investments	$	75,024	$	10	$	(54	)	$	74,980

- Definition

Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities.

+ References+ Details

Derivative Instruments (Tables)

12 Months Ended

Dec. 31, 2013

Derivative Instruments And Hedging Activities Disclosure [Abstract]

Estimated Fair Values of Derivative Instruments


			December 31, 2013						December 31, 2012
	Maturity Date		Contract/Notional Amount		Carrying Amount		Fair Value		Contract/Notional Amount		Carrying Amount		Fair Value

Interest rate cap agreement⁽¹⁾		2013	$	—	$	—	$	—	$	130 million	$	—	$	—

Interest rate cap agreement⁽¹⁾		2016	$	188 million	$	—	$	—	$	—	$	—	$	—

⁽¹⁾	Agreements limit the LIBOR floating interest rate base to 4%.

Effect of Derivatives Instruments on Combined Statements of Operations and Comprehensive Income


	2013			2012			2011
Deferred gains (losses) from derivatives in OCI, beginning of period	$	(182	)	$	(409	)	$	(532	)
Gain (loss) recognized in OCI from derivative instruments		(82	)		—			123
Gain (loss) reclassified from Accumulated OCI		185			227			—

Deferred gains (losses) from derivatives in OCI, end of period	$	(79	)	$	(182	)	$	(409	)

Equity-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2013

Summary of Activity with Respect to Equity Incentive Units

Our activity with respect to Class C equity incentive units for 2013, 2012, and 2011 was as follows:


	Number of Class C Units			Class C Unit Grant Date Weighted Average Fair Value
Unvested, December 31, 2010		2,418,834		$	0.52
Granted		—			—
Vested		(499,542	)	$	0.52
Forfeited		(867,625	)	$	0.52

Unvested, December 31, 2011		1,051,667		$	0.52
Granted		—			—
Vested		(420,667	)	$	0.52
Forfeited		(210,333	)	$	0.52

Unvested, December 31, 2012		420,667		$	0.52
Granted		—			—
Vested		(420,667	)	$	0.52
Forfeited		—			—

Unvested, December 31, 2013		—		$	—

Summary of Activity with Respect to Stock Options

Our activity with respect to stock options for the years ended December 31, 2013, 2012 and 2011 was as follows:


	Number of Shares			Range of Exercise Prices		Weighted Average Exercise Price		Fair Value
Unvested, July 8, 2011 (plan inception)		—			—		—		—
Granted		1,650,386		$	10.33 – 25.00	$	14.56	$	4.36
Exercised		—			—		—		—
Vested		—			—		—		—
Forfeited		(148,988	)		—	$	14.21	$	3.81

Unvested, December 31, 2011		1,501,398		$	10.33 – 25.00	$	14.60	$	3.74
Granted		572,847		$	10.57 – 24.00		14.15	$	5.68
Exercised		(9,528	)		10.33		10.33		4.67
Vested		—			—		—		—
Forfeited		(241,317	)		—		15.34		4.47

Unvested, December 31, 2012		1,823,400		$	10.33 – 25.00	$	14.38	$	5.04
Granted		140,000		$	20.03 – 24.59		22.48	$	10.03
Exercised		(551,165	)		10.33 – 25.00		14.41		4.35
Vested		—			—		—		—
Forfeited		(180,695	)		—		16.30		5.93

Unvested, December 31, 2013		1,231,540		$	10.33 – 25.00	$	15.01	$	5.39

Equity Units [Member]

Assumptions Used in Black-Scholes Pricing Model

The following table illustrates the assumptions used in the Black-Scholes pricing model:


Risk-free interest rate	1.87	%
Expected volatility	50	%
Expected term	4 years

Equity Securities [Member]

Assumptions Used in Black-Scholes Pricing Model

The following table illustrates the assumptions used in the Black-Scholes pricing model for options granted during the respective fiscal year:


	2013			2012
Risk-free interest rate		1.03 – 1.31	%		0.83 – 1.05	%
Expected volatility		45	%		45	%
Expected term		6.25 years			6.25 years
Expected dividend yield		0	%		0	%
Expected forfeiture yield		0	%		0	%

Restricted Stock [Member]

Summary of Activity with Respect to Stock Options

As of December 31, 2013, there was $2.1 million of total unrecognized compensation expense related to these restricted stock shares, which is expected to be recognized over a period of 2.3 years.


	Number of Shares			Grant Date Weighted Average Fair Value
Unvested, December 31, 2012		70,000		$	15.58
Granted		180,069			22.58
Vested		(21,666	)		17.11
Forfeited		—			—

Unvested, December 31, 2013		228,403		$	20.95

Leases (Tables)

12 Months Ended

Dec. 31, 2013

Leases [Abstract]

Future Minimum Annual Commitments under Operating Leases

Future minimum annual commitments under such operating leases at December 31, 2013 are as follows:


2014		23,722
2015		21,915
2016		19,726
2017		17,614
2018		16,326
Thereafter		36,125

Total future lease commitments	$	135,428

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2013

Income Tax Disclosure [Abstract]

Summary of Income Tax (Expense) Benefit

The (expense) benefit for income taxes consisted of the following for the years ended December 31, 2013, 2012 and 2011.


	Years Ended December 31,
	2013			2012			2011
Current:
Federal	$	(20,819	)	$	(22,165	)	$	(3,222	)
State		(1,831	)		(6,237	)		(51	)

		(22,650	)		(28,402	)		(3,273	)

Deferred:
Federal		1,453			(3,645	)		(2,624	)
State		436			1,396			(1,265	)

		1,889			(2,249	)		(3,889	)

Income tax expense	$	(20,761	)	$	(30,651	)	$	(7,162	)

Summary of Tax Effects on Deferred Tax Assets and Liabilities

The tax effects of the types of temporary differences and carry forwards that gave rise to deferred tax assets and liabilities at December 31, 2013 and 2012 consisted of the following:


	At December 31,
	2013			2012
Gross deferred tax assets:
State tax credits and net operating loss carry forward	$	1,007		$	924
Pension and post-retirement benefit costs		15,579			22,427
Alternative minimum tax credit carry forward		22,528			25,889
Property, plant and equipment		6,109			5,113
Accrued expenses		3,818			2,272
Inventories		5,863			1,689
Third-party products liability		674			531
Stock-based compensation expense		1,306			1,262
Other		5,502			6,019

Total deferred tax assets	$	62,386		$	66,126

Gross deferred tax liabilities:
Land and mineral property basis difference	$	(61,366	)	$	(60,954	)
Fixed assets and depreciation		(47,016	)		(46,396	)
Intangible assets		(6,788	)		(6,957	)
Other		(797	)		(822	)

Total deferred tax liabilities		(115,967	)		(115,129	)

Net deferred tax liabilities		(53,581	)		(49,003	)
Less: Net current deferred tax assets		(17,737	)		(10,108	)

Net long-term deferred tax liabilities	$	(71,318	)	$	(59,111	)

Summary of Effective Income Tax Rate on Pretax Earnings

The effective income tax rate on pretax earnings differed from the U.S. federal statutory rate for the years ended December 31, 2013, 2012 and 2011 for the following reasons:


	Years Ended December 31,
	2013			2012			2011
(Expense) benefit computed at U.S. federal statutory rate		(35.0	)%		(35.0	)%		(35.0	)%
Decrease (increase) resulting from:
Percentage depletion		11.0			9.9			17.5
Prior year tax return reconciliation		1.9			(0.5	)		0.4
State income taxes, net of federal benefit		(2.4	)		(2.7	)		(1.6	)
Domestic production deduction		2.4			0.7			—
Medicare Part D subsidy		—			—			(0.1	)
Equity-based compensation		—			(0.1	)		(0.2	)
Other, net		0.5			(0.2	)		(0.1	)

Income tax (expense) benefit		(21.6	)%		(27.9	)%		(19.1	)%

Pension and Post-Retirement Benefits (Tables)

12 Months Ended

Dec. 31, 2013

Compensation And Retirement Disclosure [Abstract]

Summarizes Information about Pension and Post-Retirement Benefit Plans

Net pension benefit cost consisted of the following for the years ended December 31, 2013, 2012 and 2011:


	Years Ended December 31,
	2013			2012			2011
Service cost—benefits earned during the period	$	1,280		$	1,118		$	1,145
Interest cost		4,198			4,734			4,755
Expected return on plan assets		(5,061	)		(5,381	)		(4,817	)
Net amortization and deferral		1,904			1,105			595

Net pension benefit costs	$	2,321		$	1,576		$	1,678

Net post-retirement cost consisted of the following for the years ended December 31, 2013, 2012 and 2011:


	Years Ended December 31,
	2013			2012			2011
Service cost—benefits earned during the period	$	193		$	197		$	185
Interest cost		947			1,163			1,161
Expected return on plan assets		(4	)		(4	)		(5	)
Net amortization and deferral		87			177			—

Net post-retirement costs	$	1,223		$	1,533		$	1,341

Changes in Benefit Obligations and Plan Assets

The changes in benefit obligations and plan assets, as well as the funded status of our pension and post-retirement plans at December 31, 2013 and 2012 were as follows:


	Pension Benefits						Post-retirement Benefits
	2013			2012			2013			2012
Benefit obligation at January 1,	$	107,619		$	100,083		$	25,717		$	26,528
Service cost		1,280			1,118			193			197
Interest cost		4,198			4,734			947			1,163
Actuarial gain (loss)		(8,071	)		10,255			(3,933	)		(1,087	)
Benefits paid		(5,749	)		(9,238	)		(1,102	)		(1,529	)
Amendments		551			667			—			—
Other		—			—			439			445

Benefit obligation at December 31,	$	99,828		$	107,619		$	22,261		$	25,717

Fair value of plan assets at January 1,	$	80,850		$	74,596		$	54		$	54
Actual return on plan assets		7,986			10,711			8			—
Employer contributions		2,280			4,781			652			1,084
Benefits paid		(5,749	)		(9,238	)		(1,102	)		(1,529	)
Other		—			—			439			445

Fair value of plan assets at December 31,	$	85,367		$	80,850		$	51		$	54

Plan assets less than benefit obligations at December 31 recognized as liability for pension and other post-retirement benefits	$	(14,461	)	$	(26,768	)	$	(22,210	)	$	(25,664	)

Estimated Future Pension and Post-Retirement Benefit Payments

Future estimated annual benefit payments for pension and post-retirement benefit obligations as of December 31, 2013 are as follows:


	Benefits
			Post-retirement
	Pension		Before Medicare Subsidy		After Medicare Subsidy
2014		6,104		1,524		1,354
2015		6,295		1,550		1,369
2016		6,514		1,596		1,404
2017		6,802		1,696		1,495
2018		7,039		1,722		1,513
2019-2022		36,711		9,080		7,960

Amounts in Accumulated Other Comprehensive Income Expected to be Recognized as Components of Net Periodic Benefit Cost

The amounts in accumulated other comprehensive income expected to be recognized as components of net periodic benefit cost during the 2014 fiscal year are as follows:


	Benefits
	Pension		Post-retirement		Total
Net actuarial loss	$	485	$	—	$	485
Prior service cost		201		—		201

	$	686	$	—	$	686

Company's Obligations Determined under Weighted-Average Assumptions

The following weighted-average assumptions were used to determine our obligations under the plans:


	Pension Benefits						Post-retirement Benefits
	2013			2012			2013			2012
Discount rate		4.8	%		4.00	%		4.8	%		4.00	%
Long-term rate of compensation increase		3.5	%		3.50	%		N/A			N/A
Long-term rate of return on plan assets		7.5	%		8.00	%		7.5	%		8.00	%
Health care cost trend rate:
Pre-65 initial rate/ultimate rate		N/A			N/A			8%/5	%		8.5%/5	%
Pre-65 ultimate year		N/A			N/A			0			0
Post-65 initial rate/ultimate rate		N/A			N/A			7.3%/5	%		7.5%/5	%
Post-65 ultimate year		N/A			N/A			2021			2020

Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates

A one-percentage-point change in assumed health care cost trend rates would have the following effects:


	One-Percentage-Point
	Increase		Decrease
Effect on total of service and interest cost	$	145	$	(122	)
Effect on post-retirement benefit obligation		2,535		(2,163	)

Fair Value of Pension Plan Assets

The major investment categories and their relative percentage of the fair value of total plan assets as invested at December 31, 2013 and 2012 were as follows:


	Pension Benefits						Post-retirement Benefits
	2013			2012			2013			2012
Equity securities		57.4	%		59.9	%		59.0	%		58.7	%
Debt securities		36.6	%		38.6	%		29.5	%		39.2	%
Cash		6.0	%		1.5	%		11.5	%		2.1	%

Fair Value of Pension Plan Assets, by Asset Category

The fair values of the pension plan assets at December 31, 2013, by asset category, are as follows:


	Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	5,067	$	—	$	—	$	5,067
Mutual funds:
Diversified emerging markets		7,753		—		—		7,753
Foreign large blend		13,851		—		—		13,851
Large-cap blend		17,804		—		—		17,804
Long-term bonds		31,230		—		—		31,230
Mid-cap blend		5,807		—		—		5,807
Real estate		3,776		—		—		3,776
Insurance policies		—		—		79		79

Net asset	$	85,288	$	—	$	79	$	85,367

The fair values of the pension plan assets at December 31, 2012, by asset category, are as follows:


	Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	1,208	$	—	$	—	$	1,208
Mutual funds:
Diversified emerging markets		8,186		—		—		8,186
Foreign large blend		13,827		—		—		13,827
Large-cap blend		16,666		—		—		16,666
Long-term bonds		31,198		—		—		31,198
Mid-cap blend		5,650		—		—		5,650
Real estate		4,026		—		—		4,026
Insurance policies		—		—		89		89

Net asset	$	80,761		—	$	89	$	80,850

Summary of Multiemployer Pension Plan

A summary of each multiemployer pension plan for which we participate is presented below:

Pension

Fund

EIN/ Pension
Plan No.

Pension Protection Act
Zone Status⁽¹⁾

FIP/RP Status
Pending/
Implemented

Company
Contributions

Surcharge
Imposed

Expiration
Date of
CBA

2013

2012

2013

2012

2011

LIUNA

52-6074345/001

Red

Yes

124

123

116

Yes

5/31/2014

IUOE

36-6052390/001

Green

7/31/2015

CSSS⁽²⁾

36-6044243/001

Red

Yes

⁽¹⁾	The Pension Protection Act of 2006 defines the zone status as follows: green—healthy, yellow—endangered, orange—seriously endangered and red—critical.

⁽²⁾	In 2011, we withdrew from the Central States, Southeast and Southwest Areas Pension Plan. The withdrawal liability of $1.0 million will be paid in monthly installments of $4 until 2031.

Segment Reporting (Tables)

12 Months Ended

Dec. 31, 2013

Segment Reporting [Abstract]

Presentation of Sales and Segment Contribution Margin for Reporting Segments and Other Operating Results


	Years Ended December 31,
	2013			2012			2011

Sales:
Oil and gas proppants	$	347,439		$	243,765		$	107,074
Industrial and specialty products		198,546			198,156			188,522

Total sales		545,985			441,921			295,596
Segment contribution margin:
Oil and gas proppants		145,916			140,070			67,590
Industrial and specialty products		56,983			53,601			53,013

Total segment contribution margin		202,899			193,671			120,603
Operating activities excluded from segment cost of goods sold		(5,481	)		(8,285	)		(6,203	)
Selling, general and administrative		(49,759	)		(41,299	)		(23,348	)
Advisory fees to parent		—			—			(9,250	)
Depreciation, depletion and amortization		(36,418	)		(25,099	)		(20,999	)
Interest expense		(15,341	)		(13,795	)		(18,407	)
Early extinguishment of debt		(480	)		—			(6,043	)
Other income, net, including interest income		597			4,612			1,062

Income (loss) before income taxes	$	96,017		$	109,805		$	37,415

Unaudited Supplementary Data (Tables)

12 Months Ended

Dec. 31, 2013

Text Block [Abstract]

Unaudited Quarterly Information

This unaudited quarterly information has been prepared on the same basis as our annual audited financial statements and includes all adjustments, consisting only of normal recurring adjustments that are necessary to present fairly the financial information for the fiscal quarters presented.


	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
2013:
Sales	$	122,311		$	129,828		$	144,372		$	149,474
Costs of goods sold		74,412			80,297			90,983			102,875
Operating expenses
Selling, general and administrative		12,404			10,099			12,800			14,456
Depreciation, depletion and amortization		8,278			8,890			9,152			10,098

		20,682			18,989			21,952			24,554

Operating income		27,217			30,542			31,437			22,045
Other (expense) income
Interest expense		(3,576	)		(3,535	)		(4,144	)		(4,086	)
Early extinguishment of debt		—			—			(480	)		—
Other income, net, including interest income		122			63			260			152

		(3,454	)		(3,472	)		(4,364	)		(3,934	)

Income before income taxes		23,763			27,070			27,073			18,111
Income tax expense		(6,486	)		(6,878	)		(5,739	)		(1,658	)

Net income	$	17,277		$	20,192		$	21,334		$	16,453

Earnings per share, basic	$	0.33		$	0.38		$	0.40		$	0.31
Earnings per share, diluted	$	0.32		$	0.38		$	0.40		$	0.31
Weighted average common shares outstanding (in thousands), basic		52,946			52,948			53,103			53,035
Weighted average common shares outstanding (in thousands), diluted		52,211			53,227			53,429			53,409

	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
2012:
Sales	$	102,591		$	104,599		$	115,885		$	118,846
Costs of goods sold		56,921			58,920			69,706			70,988
Operating expenses
Selling, general and administrative		9,904			9,718			10,135			11,542
Depreciation, depletion and amortization		5,978			5,974			5,968			7,179

		15,882			15,692			16,103			18,721

Operating income		29,788			29,987			30,076			29,137
Other (expense) income
Interest expense		(3,797	)		(3,428	)		(3,326	)		(3,244	)
Other income, net, including interest income		154			179			348			3,931

		(3,643	)		(3,249	)		(2,978	)		687

Income before income taxes		26,145			26,738			27,098			29,824
Income tax (expense) benefit		(7,032	)		(7,287	)		(8,302	)		(8,030	)

Net income	$	19,113		$	19,451		$	18,796		$	21,794

Earnings per share, basis and diluted	$	0.37		$	0.37		$	0.36		$	0.41
Weighted average common shares outstanding (in thousands), basic		51,939			52,440			52,873			52,891
Weighted average common shares outstanding (in thousands), diluted		52,031			52,505			52,887			52,963

Organization - Additional Information (Detail) (USD $)						0 Months Ended		12 Months Ended		0 Months Ended
Organization - Additional Information (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Jan. 31, 2012	Jul. 08, 2011	Nov. 25, 2008	Jan. 31, 2012 Convertible Note Payable [Member]	Feb. 06, 2012 IPO [Member]	Dec. 31, 2013 IPO [Member]	Jan. 31, 2012 IPO [Member]	Jan. 31, 2012 IPO [Member] Promissory Note [Member]
Organization And Nature Of Business [Line Items]
Common stock issued	53,492,278	52,920,704			1,000		2,941,176
Aggregate purchase price	$ 534,000	$ 529,000			$ 10.00
Common stock authorized	500,000,000		500,000,000	100,000,000					2,941,176
Split ratio of common stock				50,000-for-one split
Authorized preferred stock	10,000,000		10,000,000
Stockholders common stock issued							8,823,529
Common stock, offering price							$ 17.00
Aggregate offering price at common stock							50,000,000
Underwriting discounts and commissions								3,500,000
Offering expenses								5,700,000
Net proceeds								40,800,000
Aggregate offering price at stockholders common stock							150,000,000
GGC RCS Holdings, Inc.-note payable converted to equity contribution						15,000,000
Accrued interest										$ 1,700,000
Percentage of Interest held	0.00%

Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013 Customer	Dec. 31, 2012	Dec. 31, 2011
Organization And Significant Accounting Policies [Line Items]
Number of customers in the oil & gas proppants segment	7
Agreements expiring period	2013
Agreements expiring period	2016
Standard term invoice	30 days
Accounts receivable due	30 days
Number of customers accounted for sales percentage	10
Reversal of reclamation obligations	$ 2,300,000
Other long-term obligations	13,951,000	10,176,000
Percentage of fair value of reporting unit less than carrying amount	50.00%
Estimated annual amortization	411,000
Estimated annual amortization	411,000
Estimated annual amortization	411,000
Estimated annual amortization	411,000
Estimated annual amortization	411,000
Amortization in interest expense	680,000	515,000	265,000
Self-insurance reserve total	5,400,000	4,000,000
Self-insurance reserve current	1,700,000	1,300,000
Percentage of refund from taxing authority	50.00%
Short-term and fixed income securities with maturities	12 months or less
Long-term and fixed income securities with maturities	Greater than 12 months
Amendment effective date	December 15, 2013
Buildings [Member]
Organization And Significant Accounting Policies [Line Items]
Depreciation over the assets estimated useful life	15 years
Land Improvements [Member]
Organization And Significant Accounting Policies [Line Items]
Depreciation over the assets estimated useful life	10 years
Furniture and Fixtures [Member]
Organization And Significant Accounting Policies [Line Items]
Depreciation over the assets estimated useful life	8 years
No Single Individual Customer [Member]
Organization And Significant Accounting Policies [Line Items]
Maximum percentage of sales accounted by an individual customer	10.00%	10.00%	10.00%
Customer relationships [Member]
Organization And Significant Accounting Policies [Line Items]
Weighted average amortization useful life	20 years
Remaining useful life	14 years 10 months 24 days
Gross carrying amount of intangible asset	8,200,000
Accumulated amortization	2,100,000
Minimum [Member]
Organization And Significant Accounting Policies [Line Items]
Self-insured retentions	100,000
Minimum [Member] \| Machinery and Equipment [Member]
Organization And Significant Accounting Policies [Line Items]
Depreciation over the assets estimated useful life	3 years
Maximum [Member]
Organization And Significant Accounting Policies [Line Items]
Self-insured retentions	500,000
Maximum [Member] \| Machinery and Equipment [Member]
Organization And Significant Accounting Policies [Line Items]
Depreciation over the assets estimated useful life	10 years
Sales Revenue, Net [Member]
Organization And Significant Accounting Policies [Line Items]
Percentage of sales in which customers accounted	52.00%	37.00%	44.00%
Other long-term obligations [Member]
Organization And Significant Accounting Policies [Line Items]
Other long-term obligations	$ 9,400,000	$ 6,700,000

Summary of Significant Accounting Policies - Change in Asset Retirement Obligation (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Accounting Policies [Abstract]
Beginning balance	$ 6,659	$ 9,504
Payments
Accretion	456	658
Revisions of prior estimates	2,263	(3,503)
Ending balance	$ 9,378	$ 6,659

Earnings Per Share - Schedule of Basic and Diluted Earnings Per Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share [Abstract]
Net income	$ 16,453	$ 21,334	$ 20,192	$ 17,277	$ 21,794	$ 18,796	$ 19,451	$ 19,113	$ 75,256	$ 79,154	$ 30,253
Less: net income allocated to outstanding restricted stockholders									(175)	(105)
Net income allocated to common stockholders									$ 75,081	$ 79,049	$ 30,253
Outstanding	53,035,000	53,103,000	52,948,000	52,946,000	52,891,000	52,873,000	52,440,000	51,939,000	53,035	52,592	50,000
Outstanding assuming dilution									53,409	52,641	50,006

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

Capital Structure and Accumulated Comprehensive Income - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended							0 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Oct. 24, 2013	Jan. 31, 2012	Jul. 08, 2011	Nov. 25, 2008	Jun. 11, 2012 Common Stock [Member]	Dec. 31, 2013 Common Stock [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Common stock authorized, shares	500,000,000				500,000,000	100,000,000
Common stock, par value	$ 0.01
Common stock issued	53,492,278	52,920,704					1,000
Common stock, shares outstanding	53,492,278	52,920,704
Quarterly cash dividend declared				$ 0.125
Dividend declared date	Oct. 24, 2013
Dividend declared, record date	Dec. 16, 2013
Dividend declared, payable date	Jan. 03, 2014
Preferred stock, shares authorized	10,000,000				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								$ 25.0
Common stock repurchase authorization period									18 months
Common stock repurchase authorization period, conclusion date									Dec. 11, 2014
Number of repurchased shares, common stock									100,000
Repurchased common stock, average price									$ 10.72
Remaining authorized repurchase of common stock amount									$ 23.9
Re-issued shares to satisfy employee option exercises	551,165	9,528							100,000

Capital Structure and Accumulated Comprehensive Income - Changes in Accumulated Other Comprehensive Income (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (14,175)
Other comprehensive income (loss) before reclassifications	8,735
Amounts reclassed from accumulated other comprehensive income	1,423
Ending Balance	(4,017)
Unrealized Gain/(Loss) on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(182)
Other comprehensive income (loss) before reclassifications	(82)
Amounts reclassed from accumulated other comprehensive income	185
Ending Balance	(79)
Unrealized Gain/(Loss) on Short-Term Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance
Other comprehensive income (loss) before reclassifications	(27)
Amounts reclassed from accumulated other comprehensive income
Ending Balance	(27)
Pension and Other Postretirement Benefits Liability [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(13,993)
Other comprehensive income (loss) before reclassifications	8,844
Amounts reclassed from accumulated other comprehensive income	1,238
Ending Balance	$ (3,911)

- Definition

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

+ References+ Details

Capital Structure and Accumulated Comprehensive Income - Reclassifications Out of Accumulated Other Comprehensive Income (Loss) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Tax expense	$ (1,658)	$ (5,739)	$ (6,878)	$ (6,486)	$ (8,030)	$ (8,302)	$ (7,287)	$ (7,032)	$ (20,761)	$ (30,651)	$ (7,162)
Amount Reclassified from Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net of tax									1,423
Amount Reclassified from Accumulated Other Comprehensive Income [Member] \| Gains and Losses on Cash Flow Hedges [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Tax expense									(119)
Net of tax									185
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)									1,933
Prior service cost									92
Total before tax									2,025
Tax expense									(787)
Net of tax									1,238
Amount Reclassified from Accumulated Other Comprehensive Income [Member] \| Interest Rate Contract [Member] \| Gains and Losses on Cash Flow Hedges [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense									$ 304

Accounts Receivable - Schedule of Accounts Receivable (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Receivables [Abstract]
Trade receivables	$ 76,223	$ 56,519
Less: Allowance for doubtful accounts	(2,376)	(1,053)
Net trade receivables	73,847	55,466
Other receivables	1,360	4,098
Total accounts receivable	$ 75,207	$ 59,564

Accounts Receivable - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenue, Major Customer [Line Items]
Net trade receivables	$ 18,381
Net trade receivables increased	$ 73,847	$ 55,466
No Single Individual Customer [Member]
Revenue, Major Customer [Line Items]
Maximum percentage of sales accounted by an individual customer	10.00%	10.00%	10.00%

Inventories - Schedule of Inventories (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Inventory Disclosure [Abstract]
Supplies	$ 15,576	$ 13,472
Raw materials and work in process	11,728	10,720
Finished goods	36,908	15,643
Total inventories	$ 64,212	$ 39,835

Inventories - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Inventory Disclosure [Abstract]
Increased in finished goods	$ 21,265
Finished goods	$ 36,908	$ 15,643

Property,Plant and Mine Development - Schedule of Property,Plant and Mine Development (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Property, plant and mine development	$ 555,435	$ 492,722
Accumulated depletion, depreciation and amortization	(113,319)	(78,504)
Total property, plant and mine development, net	442,116	414,218
Mining Property and Mine Development [Member]
Property, Plant and Equipment [Line Items]
Property, plant and mine development	164,609	163,538
Asset Retirement Cost [Member]
Property, Plant and Equipment [Line Items]
Property, plant and mine development	7,275	5,124
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and mine development	25,738	24,795
Land Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and mine development	31,093	27,604
Buildings [Member]
Property, Plant and Equipment [Line Items]
Property, plant and mine development	36,311	31,558
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and mine development	263,304	221,139
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, plant and mine development	1,131	915
Construction-In-Progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and mine development	$ 25,974	$ 18,049

Property, Plant and Mine Development - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Property Plant And Equipment [Abstract]
Depreciation expense, including depletion and amortization	$ 36,418	$ 25,099	$ 20,999
Property, plant and equipment interest capitalization	533	934	575
Capital lease obligation	$ 0

Accrued Liabilities - Schedule of Accrued Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Payables And Accruals [Abstract]
Accrued salaries and wages	$ 2,411	$ 2,939
Accrued vacation liability	2,396	2,397
Current portion of liability for pension and post-retirement benefits	1,428	1,413
Accrued healthcare liability	1,662	1,278
Other accrued liabilities	2,926	1,454
Total accrued liabilities	$ 10,823	$ 9,481

- Definition

Carrying value as of the balance sheet date of obligations incurred through that date and payable to insurance entities to mitigate potential loss from various risks or to satisfy a promise to provide certain coverage's to employees. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References+ Details

- Definition

Carrying value as of the balance sheet date of the obligations incurred through that date and payable for employees' services provided. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References+ Details

- Definition

Carrying value as of the balance sheet date of obligations incurred through that date and payable arising from transactions not otherwise specified in the taxonomy. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References+ Details

- Definition

The current liability recognized in the balance sheet that is associated with defined benefit pension plans and other postretirement and postemployment benefit plans.

+ References+ Details

Debt - Schedule of Debt (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Line of Credit Facility [Line Items]
Total debt	$ 371,451	$ 255,425
Less: current portion	(3,488)	(2,433)
Total long-term portion of debt	367,963	252,992
Senior Secured Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of credit available	$ 371,451	$ 255,425

Debt - Schedule of Debt (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Revolving Line-of-Credit [Member]
Line of Credit Facility [Line Items]
Credit facility, maturity date	Jul. 23, 2018	Oct. 31, 2016
Credit facility, interest rate	4.75%	5.00%
Senior Secured Credit Facility [Member]
Line of Credit Facility [Line Items]
Credit facility, maturity date	Jul. 23, 2020
Credit facility, interest rate	4.00%	4.75%
Term loan facility unamortized original issue discount	$ 1,674	$ 675

Debt - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Short-term Debt [Line Items]
Available borrowing base	$ 425
Expense associated with refinancing our Term Loan and replacing Revolver	1.8
Third party fees in selling general, and administrative expenses	1.3
Expense associated with related to early extinguishment of debt	0.5
Facility consolidated total net leverage ratio	0.03751
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	9.0
Amount available for general corporate use under this revolving credit agreement	41.0
New Revolver expiration Date	Jul. 23, 2018	Oct. 31, 2016
Revolving Line-of-Credit [Member] \| Minimum [Member]
Short-term Debt [Line Items]
Increase of commitment		35
Letter of credit sublimit		15
Revolving Line-of-Credit [Member] \| Maximum [Member]
Short-term Debt [Line Items]
Increase of commitment		50
Letter of credit sublimit		20
Term Loan [Member]
Short-term Debt [Line Items]
Available borrowing base	375
New Revolver expiration Date	Jul. 23, 2020
Swing Line Loans [Member]
Short-term Debt [Line Items]
Available borrowing base	5
Letter of Credit [Member]
Short-term Debt [Line Items]
Available borrowing base	$ 20

Debt - Schedule of Contractual Maturities of Debt (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013
Debt Disclosure [Abstract]
2014	$ 3,488
2015	3,490
2016	3,493
2017	3,495
2018	3,499
Thereafter	353,986
Debt, Total	$ 371,451

- Definition

Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References+ Details

Deferred Revenue - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended
	Nov. 25, 2008	Dec. 31, 2013 Notes Maturing December 31, 2015 [Member]	Dec. 31, 2009 Notes Maturing December 31, 2015 [Member]	Dec. 31, 2013 Notes Maturing November 25, 2016 [Member]
Deferred Revenue Arrangement [Line Items]
Advances received from two customers	$ 27
Rate of interest on promissory notes	10.00%
Notes maturity date		Dec. 31, 2015		Nov. 25, 2016
Revised interest rate notes value			$ 12	$ 15
Interest rate			5.00%	6.00%

Fair Value Accounting - Schedule of Measure at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Short-term investments	$ 74,980
Interest rate derivatives	109
Net asset	75,089
Measured at Fair Value on Recurring Basis [Member] \| Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Short-term investments	622
Interest rate derivatives
Net asset	622
Measured at Fair Value on Recurring Basis [Member] \| Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Short-term investments	74,358
Interest rate derivatives	109
Net asset	$ 74,467

- Definition

Fair value of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, elected not to be offset against an obligation to return collateral under a master netting arrangement.

+ References+ Details

Short-Term Investments - Schedule of Available-for-Sale Short-Term Investments (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Aggregate Cost	$ 75,024
Gross Unrealized Gains	10
Gross Unrealized Losses	(54)
Fair Value	74,980
Money Market Mutual Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Aggregate Cost	622
Gross Unrealized Gains
Gross Unrealized Losses
Fair Value	622
Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Aggregate Cost	25,218
Gross Unrealized Gains
Gross Unrealized Losses	(34)
Fair Value	25,184
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Aggregate Cost	15,168
Gross Unrealized Gains	4
Gross Unrealized Losses	(1)
Fair Value	15,171
Corporate Notes and Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Aggregate Cost	9,495
Gross Unrealized Gains
Gross Unrealized Losses	(9)
Fair Value	9,486
Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Aggregate Cost	13,979
Gross Unrealized Gains	6
Gross Unrealized Losses
Fair Value	13,985
U.S. Treasuries [Member]
Schedule of Available-for-sale Securities [Line Items]
Aggregate Cost	4,828
Gross Unrealized Gains
Gross Unrealized Losses	(10)
Fair Value	4,818
Variable Rate Demand Obligation [Member]
Schedule of Available-for-sale Securities [Line Items]
Aggregate Cost	5,714
Gross Unrealized Gains
Gross Unrealized Losses
Fair Value	$ 5,714

Derivative Instruments - Additional Information (Detail) (USD $)	12 Months Ended				12 Months Ended		12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011 MMBTU	Dec. 31, 2013 Interest Rate Cap Agreement [Member] Agreement	Dec. 31, 2013 First Agreement [Member]	Mar. 31, 2012 First Agreement [Member]	Dec. 31, 2013 Second Agreement [Member]	Mar. 31, 2012 Second Agreement [Member]	Mar. 31, 2012 Second Agreement After Reset [Member]	Apr. 08, 2013 Third Agreement [Member] Interest Rate Cap Agreement - New [Member]	Sep. 06, 2013 Fourth Agreement [Member] Interest Rate Cap Agreement - New [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative notional amount		$ 130,000,000				$ 100,000,000		$ 30,000,000		$ 128,000,000	$ 60,000,000
Derivative maturity date					Mar. 31, 2012		Jun. 30, 2013
Number of interest rate cap agreements				2
Upper limit of LIBOR for one-month	4.00%	4.00%
Notional amount after increase									130,000,000
Additional expenses reclassified from accumulated other comprehensive income or recognized directly in earnings	0
Upper limit of LIBOR for three-month										4.00%	4.00%
Derivative ineffective portion of the change in fair value	$ 0	$ 0
Cash flow hedges for natural gas			420,000

Derivative Instruments - Estimated Fair Values of Derivative Instruments (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Contract/Notional Amount		$ 130.0
Interest Rate Cap Agreement [Member] \| 2012 [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Maturity Date	2013
Contract/Notional Amount		130.0
Carrying Amount
Fair Value
Interest Rate Cap Agreement [Member] \| 2013 [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Maturity Date	2016
Contract/Notional Amount	188.0
Carrying Amount
Fair Value

Derivative Instruments - Effect of Derivatives Instruments on Combined Statements of Operations and Comprehensive Income (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Deferred gains (losses) from derivatives in OCI, beginning of period	$ (182)	$ (409)	$ (532)
Gain (loss) recognized in OCI from derivative instruments	(82)		123
Gain (loss) reclassified from Accumulated OCI	185	227
Deferred gains (losses) from derivatives in OCI, end of period	$ (79)	$ (182)	$ (409)

Equity-Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended				12 Months Ended								12 Months Ended
	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 10, 2012	Dec. 31, 2013 Restricted Stock [Member]	Dec. 31, 2013 Equity Program [Member]	Dec. 31, 2012 Equity Program [Member]	Dec. 31, 2011 Equity Program [Member]	Dec. 31, 2013 Class C Units [Member]	Dec. 31, 2012 Class C Units [Member]	Dec. 31, 2011 Class C Units [Member]	Dec. 31, 2010 Class C Units [Member]	Dec. 31, 2013 Class C Units [Member] Equity Program [Member]	Dec. 31, 2012 Class C Units [Member] Equity Program [Member]	Dec. 31, 2011 Class C Units [Member] Equity Program [Member]
Option Indexed to Issuer's Equity [Line Items]
Stock vesting period		5 years
Share Based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other than Options, Accelerated Vested in Period										210,333
Number of Shares, Vested						21,666				420,667	420,667	499,542
Recognized compensation expense						$ 976,000	$ 2,000,000	$ 2,200,000	$ 1,000,000					$ 109,000	$ 208,000	$ 239,000
Number of units forfeited											210,333	867,625		0
Reversal of allocated share based compensation expense											11,000	344,000
Cancellation of unamortized share expenses											109,000	476,000
Fair value of total equity incentive units		0	219,000	260,000
Options outstanding	1,231,540	1,231,540
Options exercisable	296,908	296,908
Outstanding options weighted-average shares		$ 14.30
Total unrecognized compensation expense						2,100,000	4,100,000
Recognized weighted-average period							2 years 4 months 24 days
Intrinsic value of stock options exercised		5,900,000
Cash received from options exercised		7,942,000
Actual tax benefit realized for the tax deductions from option exercises		$ 2,300,000
Special cash dividend declared					$ 0.50
Special cash dividend declared, quarterly	$ 0.125	$ 0.375	$ 0.50
Expected divided yield		0.00%
Restricted stock						228,403					420,667	1,051,667	2,418,834
Expected term, to recognize compensation expense		6 years 3 months	6 years 3 months			2 years 3 months 18 days

Equity-Based Compensation - Summary of Activity with Respect to Equity Incentive Units (Detail) (Class C Units [Member], USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Class C Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Units, Unvested, Beginning balance	420,667	1,051,667	2,418,834
Number of Units, Granted
Number of Units, Vested	(420,667)	(420,667)	(499,542)
Number of Units, Forfeited		(210,333)	(867,625)
Number of Units, Unvested, Ending balance		420,667	1,051,667
Fair Value, Unvested, Beginning balance	$ 0.52	$ 0.52	$ 0.52
Grand Date Weighted Average Fair Value, Granted
Grand Date Weighted Average Fair Value, Vested	$ 0.52	$ 0.52	$ 0.52
Grand Date Weighted Average Fair Value, Forfeited		$ 0.52	$ 0.52
Fair Value, Unvested, Ending balance		$ 0.52	$ 0.52

Equity-Based Compensation - Assumptions Used in Black-Scholes Pricing Model (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Fair Value Assumption Used To Determine Options Fair Value [Line Items]
Risk-free interest rate	1.03%	0.83%
Risk-free interest rate	1.31%	1.05%
Expected volatility	45.00%	45.00%
Expected term	6 years 3 months	6 years 3 months
Expected dividend yield	0.00%	0.00%
Expected forfeiture yield	0.00%	0.00%
Equity Units [Member]
Fair Value Assumption Used To Determine Options Fair Value [Line Items]
Risk-free interest rate	1.87%
Expected volatility	50.00%
Expected term	4 years

Equity-Based Compensation - Summary of Activity with Respect to Stock Options (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Unvested, Beginning balance	1,823,400	1,501,398
Number of Shares, Granted	140,000	572,847	1,650,386
Number of Shares, Exercised	(551,165)	(9,528)
Number of Shares, Vested
Number of Shares, Forfeited	(180,695)	(241,317)	(148,988)
Number of Shares, Unvested, Ending balance	1,231,540	1,823,400	1,501,398
Range of Exercise Prices, Maximum Limit		$ 10.33
Weighted Average Exercise Price, Unvested, Beginning balance	$ 14.38	$ 14.60
Weighted Average Exercise Price, Granted	$ 22.48	$ 14.15	$ 14.56
Weighted Average Exercise Price, Exercised	$ 14.41	$ 10.33
Weighted Average Exercise Price, Vested
Weighted Average Exercise Price, Forfeited	$ 16.30	$ 15.34	$ 14.21
Weighted Average Exercise Price, Unvested, Ending balance	$ 15.01	$ 14.38	$ 14.60
Fair Value, Unvested, Beginning balance	$ 5,040	$ 3,740
Fair Value, Granted	10,030	5,680	4,360
Fair Value, Exercised	4,350	4,670
Fair Value, Vested
Fair Value, Forfeited	5,930	4,470	3,810
Fair Value, Unvested, Ending balance	$ 5,390	$ 5,040	$ 3,740
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Unvested, Beginning balance	70,000
Number of Shares, Granted	180,069
Number of Shares, Vested	(21,666)
Number of Shares, Forfeited
Number of Shares, Unvested, Ending balance	228,403
Fair Value, Unvested, Beginning balance	$ 15.58
Fair Value, Granted	$ 22.58
Fair Value, Vested	$ 17.11
Fair Value, Forfeited
Fair Value, Unvested, Ending balance	$ 20.95
10.33 - 25.00 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Prices, Minimum Limit	$ 10.33	$ 10.33	$ 10.33
Range of Exercise Prices, Maximum Limit	$ 25.00	$ 25.00	$ 25.00
10.57 - 24.00 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Prices, Minimum Limit		$ 10.57
Range of Exercise Prices, Maximum Limit		$ 24.00
20.03 - 24.59 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Prices, Minimum Limit	$ 20.03
Range of Exercise Prices, Maximum Limit	$ 24.59

Leases - Future Minimum Annual Commitments under Operating Leases (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013
Leases [Abstract]
2014	$ 23,722
2015	21,915
2016	19,726
2017	17,614
2018	16,326
Thereafter	36,125
Total future lease commitments	$ 135,428

Leases - Additional Information (Detail) (USD $)	12 Months Ended
Leases - Additional Information (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Leases [Abstract]
Expense related to operating leases and rental agreements	$ 16,300,000	$ 11,900,000	$ 6,500,000
Capital lease obligation	$ 0	$ 0

Commitments and Contingencies - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2013 Claim	Dec. 31, 2012 Claim	Dec. 31, 2011 Claim
Insurance [Abstract]
New claims filed		3	2	3
Products liability claims outstanding		88
Underlying insurance policies receivable	$ 5,100,000
Third-party products claims liability under insurance in other assets	247,000	313,000	247,000
Third-party products claims liability under insurance in other long-term obligations	1,300,000	1,600,000	1,300,000
Gain and loss from pre-tax adjustments		$ 500,000	$ 3,400,000	$ 2,600,000

Income Taxes - Summary of Income Tax (Expense) Benefit (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Federal									$ (20,819)	$ (22,165)	$ (3,222)
State									(1,831)	(6,237)	(51)
Current income tax total									(22,650)	(28,402)	(3,273)
Federal									1,453	(3,645)	(2,624)
State									436	1,396	(1,265)
Deferred income tax total									1,889	(2,249)	(3,889)
Income tax expense	$ (1,658)	$ (5,739)	$ (6,878)	$ (6,486)	$ (8,030)	$ (8,302)	$ (7,287)	$ (7,032)	$ (20,761)	$ (30,651)	$ (7,162)

- Definition

Amount of current income tax expense (benefit) pertaining to taxable income (loss) from continuing operations.

+ References+ Details

- Definition

Amount of current state and local tax expense (benefit) pertaining to income (loss) from continuing operations.

+ References+ Details

- Definition

Amount of deferred federal income tax expense (benefit) pertaining to income (loss) from continuing operations.

+ References+ Details

- Definition

Amount of deferred state and local tax expense (benefit) pertaining to income (loss) from continuing operations.

+ References+ Details

Income Taxes - Summary of Tax Effects on Deferred Tax Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Gross deferred tax assets:
State tax credits and net operating loss carry forward	$ 1,007	$ 924
Pension and post-retirement benefit costs	15,579	22,427
Alternative minimum tax credit carry forward	22,528	25,889
Property, plant and equipment	6,109	5,113
Accrued expenses	3,818	2,272
Inventories	5,863	1,689
Third-party products liability	674	531
Stock-based compensation expense	1,306	1,262
Other	5,502	6,019
Total deferred tax assets	62,386	66,126
Gross deferred tax liabilities:
Land and mineral property basis difference	(61,366)	(60,954)
Fixed assets and depreciation	(47,016)	(46,396)
Intangible assets	(6,788)	(6,957)
Other	(797)	(822)
Total deferred tax liabilities	(115,967)	(115,129)
Net deferred tax liabilities	(53,581)	(49,003)
Less: Net current deferred tax assets	(17,737)	(10,108)
Net long-term deferred tax liabilities	$ (71,318)	$ (59,111)

Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
Income Taxes - Additional Information (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Alternative minimum tax credit carry forward	$ 22,500,000	$ 25,900,000
Unrecognized tax benefits	0	0
Excess tax benefit	$ 1,380,000	$ 0	$ 0

Income Taxes - Summary of Effective Income Tax Rate on Pretax Earnings (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
(Expense) benefit computed at U.S. federal statutory rate	(35.00%)	(35.00%)	(35.00%)
Percentage depletion	11.00%	9.90%	17.50%
Prior year tax return reconciliation	1.90%	(0.50%)	0.40%
State income taxes, net of federal benefit	(2.40%)	(2.70%)	(1.60%)
Domestic production deduction	2.40%	0.70%
Medicare Part D subsidy			(0.10%)
Equity-based compensation		(0.10%)	(0.20%)
Other, net	0.50%	(0.20%)	(0.10%)
Income tax (expense) benefit	(21.60%)	(27.90%)	(19.10%)

Pension and Post-Retirement Benefits - Summarizes Information about Pension and Post-Retirement Benefit Plans (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Service cost - benefits earned during the period	$ 1,280	$ 1,118	$ 1,145
Interest cost	4,198	4,734	4,755
Expected return on plan assets	(5,061)	(5,381)	(4,817)
Net amortization and deferral	1,904	1,105	595
Net pension benefit costs	2,321	1,576	1,678
Post-retirement Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Service cost - benefits earned during the period	193	197	185
Interest cost	947	1,163	1,161
Expected return on plan assets	(4)	(4)	(5)
Net amortization and deferral	87	177
Net pension benefit costs	$ 1,223	$ 1,533	$ 1,341

Pension and Post Retirement Benefits - Changes in Benefit Obligations and Plan Assets (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Employer contributions	$ 1,700	$ 1,400	$ 1,000
Post-retirement Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Benefit obligation, Beginning balance	25,717	26,528
Service cost	193	197	185
Interest cost	947	1,163	1,161
Actuarial gain (loss)	(3,933)	(1,087)
Benefits paid	(1,102)	(1,529)
Other	439	445
Benefit obligation, Ending balance	22,261	25,717	26,528
Fair value of plan assets, Beginning balance	54	54
Actual return on plan assets	8
Employer contributions	652	1,084
Benefits paid	(1,102)	(1,529)
Other	439	445
Fair value of plan assets, Ending balance	51	54	54
Plan assets less than benefit obligations at December 31 recognized as liability for pension and other post-retirement benefits	(22,210)	(25,664)
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Benefit obligation, Beginning balance	107,619	100,083
Service cost	1,280	1,118	1,145
Interest cost	4,198	4,734	4,755
Actuarial gain (loss)	(8,071)	10,255
Benefits paid	(5,749)	(9,238)
Amendments	551	667
Benefit obligation, Ending balance	99,828	107,619	100,083
Fair value of plan assets, Beginning balance	80,850	74,596
Actual return on plan assets	7,986	10,711
Employer contributions	2,280	4,781
Benefits paid	(5,749)	(9,238)
Fair value of plan assets, Ending balance	85,367	80,850	74,596
Plan assets less than benefit obligations at December 31 recognized as liability for pension and other post-retirement benefits	$ (14,461)	$ (26,768)

Pension and Post-Retirement Benefits - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation of plan assets	$ 1,600,000	$ 1,700,000
Accumulated benefit obligation of plan assets	1,600,000	1,700,000
Fair value of plan assets	0	0
Net actuarial loss	485,000
Prior service cost	201,000
Discount rate reflects the expected long-term rates of return	0.05%
Percentage of contributions to individual multiemployer pension funds	5.00%
Company contribution over defined benefit plan	4.00%
Company contributing percentage on defined benefit plan	25.00%
Employee contribution over defined benefit plan	8.00%
Company contribution on profit sharing match	75.00%
Employer contributions	1,700,000	1,400,000	1,000,000
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	99,400,000	107,000,000
Net actuarial loss	485,000
Prior service cost	201,000
Employer contributions	2,280,000	4,781,000
Pension Benefits [Member] \| Subsequent Event [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions for the post-retirement medical and life plan	4,600,000
Post-retirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	652,000	1,084,000
Post-retirement Benefits [Member] \| Subsequent Event [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions for the post-retirement medical and life plan	$ 1,400,000

Pension and Post Retirement Benefits - Estimated Future Pension and Post-Retirement Benefit Payments (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
2014	$ 6,104
2015	6,295
2016	6,514
2017	6,802
2018	7,039
2019-2022	36,711
Post-retirement Benefits [Member] \| Before Medicare Subsidy [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
2014	1,524
2015	1,550
2016	1,596
2017	1,696
2018	1,722
2019-2022	9,080
Post-retirement Benefits [Member] \| After Medicare Subsidy [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
2014	1,354
2015	1,369
2016	1,404
2017	1,495
2018	1,513
2019-2022	$ 7,960

Pension and Post Retirement Benefits - Amounts in Accumulated Other Comprehensive Income Expected to be Recognized as Components of Net Periodic Benefit Cost (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Net actuarial loss	$ 485
Prior service cost	201
Total	686
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Net actuarial loss	485
Prior service cost	201
Total	$ 686

Pension and Post Retirement Benefits - Company's Obligations Determined under Weighted-Average Assumptions (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	4.80%	4.00%
Long-term rate of compensation increase	3.50%	3.50%
Long-term rate of return on plan assets	7.50%	8.00%
Post-retirement Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	4.80%	4.00%
Long-term rate of return on plan assets	7.50%	8.00%
Post-retirement Benefits [Member] \| Pre-65 [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Ultimate year
Ultimate rate	5.00%	5.00%
Post-retirement Benefits [Member] \| Pre-65 [Member] \| Maximum [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Initial rate	8.00%	8.50%
Post-retirement Benefits [Member] \| Post-65 [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Ultimate year	2021	2020
Ultimate rate	5.00%	5.00%
Post-retirement Benefits [Member] \| Post-65 [Member] \| Minimum [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Initial rate	7.30%	7.50%

Pension and Post Retirement Beneefits - Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013
Schedule Of Sale Of Subsidiary [Abstract]
Effect on total of service and interest cost	$ 145
Effect on post-retirement benefit obligation	2,535
Effect on total of service and interest cost	(122)
Effect on post-retirement benefit obligation	$ (2,163)

Pension and Post Retirement Benefits - Fair Value of Pension Plan Assets (Detail)	Dec. 31, 2013	Dec. 31, 2012
Pension Benefits [Member] \| Equity Securities [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Percentage of the fair value of the total plan assets	57.40%	59.90%
Pension Benefits [Member] \| Debt Securities [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Percentage of the fair value of the total plan assets	36.60%	38.60%
Pension Benefits [Member] \| Cash [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Percentage of the fair value of the total plan assets	6.00%	1.50%
Post-retirement Benefits [Member] \| Equity Securities [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Percentage of the fair value of the total plan assets	59.00%	58.70%
Post-retirement Benefits [Member] \| Debt Securities [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Percentage of the fair value of the total plan assets	29.50%	39.20%
Post-retirement Benefits [Member] \| Cash [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Percentage of the fair value of the total plan assets	11.50%	2.10%

Pension and Post Retirement Beneefits - Fair Value of Pension Plan Assets, by Asset Category (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Cash and Cash Equivalents [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of pension plan assets	$ 5,067	$ 1,208
Diversified Emerging Markets [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of pension plan assets	7,753	8,186
Foreign Large Blend [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of pension plan assets	13,851	13,827
Large-Cap Blend [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of pension plan assets	17,804	16,666
Long-Term Bonds [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of pension plan assets	31,230	31,198
Mid-Cap Blend [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of pension plan assets	5,807	5,650
Real Estate [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of pension plan assets	3,776	4,026
Insurance Policies [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of pension plan assets	79	89
Net Asset [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of pension plan assets	85,367	80,850
Level 1 [Member] \| Cash and Cash Equivalents [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of pension plan assets	5,067	1,208
Level 1 [Member] \| Diversified Emerging Markets [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of pension plan assets	7,753	8,186
Level 1 [Member] \| Foreign Large Blend [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of pension plan assets	13,851	13,827
Level 1 [Member] \| Large-Cap Blend [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of pension plan assets	17,804	16,666
Level 1 [Member] \| Long-Term Bonds [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of pension plan assets	31,230	31,198
Level 1 [Member] \| Mid-Cap Blend [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of pension plan assets	5,807	5,650
Level 1 [Member] \| Real Estate [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of pension plan assets	3,776	4,026
Level 1 [Member] \| Insurance Policies [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of pension plan assets
Level 1 [Member] \| Net Asset [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of pension plan assets	85,288	80,761
Level 2 [Member] \| Insurance Policies [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of pension plan assets
Level 3 [Member] \| Insurance Policies [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of pension plan assets	79	89
Level 3 [Member] \| Net Asset [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of pension plan assets	$ 79	$ 89

Pension and Post Retirement Benefits - Summary of Multiemployer Pension Plan (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
LIUNA [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
EIN/Pension Plan No.	52-6074345/001
2012	Red	Red
2011	$ 124	$ 123	$ 116
2013	124	123	116
Imposed	Yes
Expiration Date of CBA	May 31, 2014
IUOE [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
EIN/Pension Plan No.	36-6052390/001
2012	Green	Green
2011	22	19	16
2013	22	19	16
Imposed	No
Expiration Date of CBA	Jul. 31, 2015
CSSS [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
EIN/Pension Plan No.	36-6044243/001
2012	Red	Red
2011	51	51	26
2013	$ 51	$ 51	$ 26
Imposed	NA

Pension and Post Retirement Benefits - Summary of Multiemployer Pension Plan (Parenthetical) (Detail) (Central States, Southeast and Southwest Areas Pension Plan [Member], USD $)	12 Months Ended
	Dec. 31, 2011
Central States, Southeast and Southwest Areas Pension Plan [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Withdrawal liability form Pension Plan	$ 1,000,000
Withdrawal liability paid on monthly installments	$ 4
Period of last installments	The withdrawal liability of $1.0 million will be paid in monthly installments of $4 until 2031.

Obligations Under Guarantees - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013 Vehicle
Surety Bonds [Member]
Loss Contingencies [Line Items]
Surety bonds outstanding	$ 7,700,000
Surety Bonds [Member] \| Safeco Insurance Company of America [Member]
Loss Contingencies [Line Items]
Surety bonds outstanding	513,000
Reclamation Bonds [Member]
Loss Contingencies [Line Items]
Bonds related to reclamation requirements	7,600,000
Kanawha Rail Corporation's [Member]
Loss Contingencies [Line Items]
Number of railroad cars	199
Payment of monthly rent	$ 66,000

Related Party Transactions - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended			0 Months Ended	12 Months Ended		1 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2011	Feb. 06, 2012 Golden Gate Capital Acquisition [Member]	Dec. 31, 2013 Golden Gate Capital Acquisition [Member]	Dec. 31, 2011 Golden Gate Capital Acquisition [Member] Advisory Agreement [Member]	Jan. 31, 2012 Promissory Note [Member]	Dec. 31, 2013 Promissory Note [Member]	Dec. 22, 2010 Promissory Note [Member]	Jan. 31, 2012 Promissory Note [Member] IPO [Member]
Related Party Transaction [Line Items]
Advisory fee to parent					$ 1.25	$ 1.30
Transaction fee percent					1.25%
Termination of advisory agreement				8.0
Termination fee			8.0
Additional expense	0
Promissory note with GGC USS Holdings, LLC.									15.0
Promissory note, maturity date								Dec. 22, 2015
Interest rate of promissory note									10.00%
Promissory note, payment terms								Outstanding principal and interest under the note was payable upon demand, but no later than the maturity date. Upon sole election by the parent, any unpaid interest could be paid in cash on December 22 of each year until the maturity date.
Accrued interest										1.7
Conversion of promissory note to equity							$ 15
Percentage of Interest held		0.00%

Segment Reporting - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 Segment Product	Dec. 31, 2012
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
Maximum percentage of net sales	10.00%
Goodwill Related Segment [Member]
Segment Reporting Information [Line Items]
Goodwill	68,400
Oil and Gas Proppants [Member]
Segment Reporting Information [Line Items]
Goodwill	47,700
Industrial and Specialty Products [Member]
Segment Reporting Information [Line Items]
Goodwill	$ 20,700

Segment Reporting - Presentation of Sales and Segment Contribution Margin for Reporting Segments and Other Operating Results (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Total sales	$ 149,474	$ 144,372	$ 129,828	$ 122,311	$ 118,846	$ 115,885	$ 104,599	$ 102,591	$ 545,985	$ 441,921	$ 295,596
Total segment contribution margin									202,899	193,671	120,603
Operating activities excluded from segment cost of goods sold									(5,481)	(8,285)	(6,203)
Selling, general and administrative	(14,456)	(12,800)	(10,099)	(12,404)	(11,542)	(10,135)	(9,718)	(9,904)	(49,759)	(41,299)	(23,348)
Advisory fees to parent											(9,250)
Depreciation, depletion and amortization	(10,098)	(9,152)	(8,890)	(8,278)	(7,179)	(5,968)	(5,974)	(5,978)	(36,418)	(25,099)	(20,999)
Interest expense	(4,086)	(4,144)	(3,535)	(3,576)	(3,244)	(3,326)	(3,428)	(3,797)	(15,341)	(13,795)	(18,407)
Early extinguishment of debt									(480)		(6,043)
Other income, net, including interest income	152	260	63	122	3,931	348	179	154	597	4,612	1,062
Income (loss) before income taxes	18,111	27,073	27,070	23,763	29,824	27,098	26,738	26,145	96,017	109,805	37,415
Reporting Segments [Member]
Segment Reporting Information [Line Items]
Advisory fees to parent											(9,250)
Operating Segments [Member] \| Oil and Gas Proppants [Member]
Segment Reporting Information [Line Items]
Total sales									347,439	243,765	107,074
Total segment contribution margin									145,916	140,070	67,590
Operating Segments [Member] \| Industrial and Specialty Products [Member]
Segment Reporting Information [Line Items]
Total sales									198,546	198,156	188,522
Total segment contribution margin									$ 56,983	$ 53,601	$ 53,013

Unaudited Supplementary Data - Unaudited Quarterly Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Information Disclosure [Abstract]
Sales	$ 149,474	$ 144,372	$ 129,828	$ 122,311	$ 118,846	$ 115,885	$ 104,599	$ 102,591	$ 545,985	$ 441,921	$ 295,596
Costs of goods sold	102,875	90,983	80,297	74,412	70,988	69,706	58,920	56,921	348,567	256,535	181,196
Operating expenses
Selling, general and administrative	14,456	12,800	10,099	12,404	11,542	10,135	9,718	9,904	49,759	41,299	23,348
Depreciation, depletion and amortization	10,098	9,152	8,890	8,278	7,179	5,968	5,974	5,978	36,418	25,099	20,999
Total operating expenses	24,554	21,952	18,989	20,682	18,721	16,103	15,692	15,882	86,177	66,398	53,597
Operating income	22,045	31,437	30,542	27,217	29,137	30,076	29,987	29,788	111,241	118,988	60,803
Other (expense) income
Interest expense	(4,086)	(4,144)	(3,535)	(3,576)	(3,244)	(3,326)	(3,428)	(3,797)	(15,341)	(13,795)	(18,407)
Early extinguishment of debt		(480)							(480)		(6,043)
Other income, net, including interest income	152	260	63	122	3,931	348	179	154	597	4,612	1,062
Total other (expenses) benefit	(3,934)	(4,364)	(3,472)	(3,454)	687	(2,978)	(3,249)	(3,643)	(15,224)	(9,183)	(23,388)
Income before income taxes	18,111	27,073	27,070	23,763	29,824	27,098	26,738	26,145	96,017	109,805	37,415
Income tax (expense) benefit	(1,658)	(5,739)	(6,878)	(6,486)	(8,030)	(8,302)	(7,287)	(7,032)	(20,761)	(30,651)	(7,162)
Net income	$ 16,453	$ 21,334	$ 20,192	$ 17,277	$ 21,794	$ 18,796	$ 19,451	$ 19,113	$ 75,256	$ 79,154	$ 30,253
Earnings per share, basic	$ 0.31	$ 0.40	$ 0.38	$ 0.33					$ 1.42	$ 1.50	$ 0.61
Earnings per share, basis and diluted					$ 0.41	$ 0.36	$ 0.37	$ 0.37
Earnings per share, diluted	$ 0.31	$ 0.40	$ 0.38	$ 0.32					$ 1.41	$ 1.50	$ 0.61
Weighted average common shares outstanding (in thousands), basic	53,035,000	53,103,000	52,948,000	52,946,000	52,891,000	52,873,000	52,440,000	51,939,000	53,035	52,592	50,000
Weighted average common shares outstanding (in thousands), diluted	53,409,000	53,429,000	53,227,000	52,211,000	52,963,000	52,887,000	52,505,000	52,031,000

Subsequent Events - Additional Information (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended	1 Months Ended
	Dec. 31, 2013	Jan. 03, 2014 Subsequent Event [Member]
Subsequent Event [Line Items]
Cash dividend paid		$ 0.125
Dividend declared date	Oct. 24, 2013	Dec. 16, 2013
Dividend declared, record date	Dec. 16, 2013	Oct. 24, 2013
Surety bonds		$ 4.4