Continental Building Products (CBPX) 10-Q 3 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Aug. 01, 2018
Document and Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Trading Symbol	CBPX
Entity Registrant Name	CONTINENTAL BUILDING PRODUCTS, INC.
Entity Central Index Key	1,592,480
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		36,967,770

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Net sales	$ 139,268	$ 120,630	$ 256,070	$ 241,245
Costs, expenses and other income:
Cost of goods sold	98,263	89,817	184,879	179,441
Selling and administrative	10,445	9,193	19,869	18,497
Total costs and operating expenses	108,708	99,010	204,748	197,938
Operating income	30,560	21,620	51,322	43,307
Other expense, net	(87)	(135)	(227)	(779)
Interest expense, net	(2,694)	(3,062)	(5,414)	(5,978)
Income before (losses)/income from equity method investment and provision for income taxes	27,779	18,423	45,681	36,550
(Losses)/income from equity method investment	(391)	345	(755)	175
Income before provision for income taxes	27,388	18,768	44,926	36,725
Provision for income taxes	(5,493)	(6,370)	(9,385)	(12,100)
Net income	$ 21,895	$ 12,398	$ 35,541	$ 24,625
Net income per share:
Basic (usd per share)	$ 0.59	$ 0.32	$ 0.96	$ 0.63
Diluted (usd per share)	$ 0.59	$ 0.32	$ 0.95	$ 0.62
Weighted average shares outstanding:
Basic (shares)	36,879,774	39,125,571	37,154,750	39,349,674
Diluted (shares)	37,027,997	39,210,219	37,314,947	39,454,928

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 21,895	$ 12,398	$ 35,541	$ 24,625
Foreign currency translation adjustment	(313)	440	(795)	564
Net gains/(losses) on derivatives, net of taxes	452	(598)	1,498	(578)
Other comprehensive income/(loss)	139	(158)	703	(14)
Comprehensive income	$ 22,034	$ 12,240	$ 36,244	$ 24,611

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Assets:
Cash and cash equivalents	$ 84,365	$ 72,521
Trade receivables, net	43,314	38,769
Inventories, net	27,662	24,882
Prepaid and other current assets	8,280	11,267
Total current assets	163,621	147,439
Property, plant and equipment, net	292,451	294,003
Customer relationships and other intangibles, net	66,284	70,807
Goodwill	119,945	119,945
Equity method investment	8,867	9,263
Debt issuance costs	387	477
Total Assets	651,555	641,934
Liabilities:
Accounts payable	30,437	30,809
Accrued and other liabilities	10,259	11,940
Notes payable, current portion	1,685	1,702
Total current liabilities	42,381	44,451
Deferred taxes and other long-term liabilities	15,456	15,847
Notes payable, non-current portion	262,807	263,610
Total Liabilities	320,644	323,908
Shareholders' Equity:
Undesignated preferred stock, par value $0.001 per share; 10,000,000 shares authorized, no shares issued and outstanding	0	0
Common stock, $0.001 par value per share; 190,000,000 shares authorized; 44,413,204 and 44,321,776 shares issued and 36,748,879 and 37,532,959 shares outstanding as of June 30, 2018 and December 31, 2017, respectively	44	44
Additional paid-in capital	326,594	325,391
Less: Treasury stock	(167,919)	(143,357)
Accumulated other comprehensive loss	(1,946)	(2,649)
Accumulated earnings	174,138	138,597
Total Shareholders' Equity	330,911	318,026
Total Liabilities and Shareholders' Equity	$ 651,555	$ 641,934

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Undesignated preferred stock, par value (usd per share)	$ 0.001	$ 0.001
Undesignated preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Undesignated preferred stock, shares issued (in shares)	0	0
Undesignated preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (usd per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	190,000,000	190,000,000
Common stock, shares issued (in shares)	44,413,204	44,321,776
Common stock, shares outstanding (in shares)	36,748,879	37,532,959

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net income	$ 35,541	$ 24,625
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	21,386	23,760
Amortization of debt issuance costs and debt discount	629	586
Losses/(income) from equity method investment	755	(175)
Amortization of deferred gain on terminated swaps	(317)	0
Loss on debt extinguishment	0	686
Share-based compensation	1,611	1,479
Deferred taxes	0	92
Change in assets and liabilities:
Trade receivables	(4,647)	(4,942)
Inventories	(2,896)	(1,811)
Prepaid expenses and other current assets	4,369	984
Accounts payable	(2,078)	(564)
Accrued and other current liabilities	(955)	(2,038)
Other long-term liabilities	(622)	(188)
Net cash provided by operating activities	52,776	42,494
Cash flows from investing activities:
Capital expenditures	(13,006)	(8,070)
Software purchased or developed	(790)	(133)
Capital contributions to equity method investment	(438)	(647)
Distributions from equity method investment	78	214
Net cash used in investing activities	(14,156)	(8,636)
Cash flows from financing activities:
Proceeds from exercise of stock options	11	230
Tax withholdings on share-based compensation	(547)	(240)
Proceeds from debt refinancing	0	273,625
Disbursements for debt refinancing	0	(273,625)
Payments of financing costs	0	(649)
Principal payments for debt	(1,358)	(1,368)
Payments to repurchase common stock	(24,562)	(27,836)
Net cash used in financing activities	(26,456)	(29,863)
Effect of foreign exchange rates on cash and cash equivalents	(320)	316
Net change in cash and cash equivalents	11,844	4,311
Cash, beginning of period	72,521	51,536
Cash, end of period	$ 84,365	$ 55,847

Background and Nature of Operat

Background and Nature of Operations	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Background and Nature of Operations	BACKGROUND AND NATURE OF OPERATIONS Description of Business Continental Building Products, Inc. (the "Company") is a Delaware corporation. Prior to the acquisition of the gypsum division of Lafarge North America Inc. ("Lafarge N.A.") described below, the Company had no operating activity. The Company manufactures gypsum wallboard related products for commercial and residential buildings and houses. The Company operates a network of three highly efficient wallboard facilities, all located in the eastern United States, and produces joint compound at one plant in the United States and at another plant in Canada. The Acquisition On June 24, 2013 , the Company's former controlling stockholder, entered into a definitive agreement with Lafarge N.A. to purchase the assets of its North American gypsum division for an aggregate purchase price of approximately $703 million (the "Acquisition") in cash. The closing of the Acquisition occurred on August 30, 2013 .

Significant Accounting Policies

Significant Accounting Policies	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Significant Accounting Policies	SIGNIFICANT ACCOUNTING POLICIES (a) Basis of Presentation The accompanying consolidated financial statements for the Company have been prepared in accordance with accounting principles generally accepted in the United States ("U.S. GAAP"). The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany transactions have been eliminated. (b) Basis of Presentation for Interim Periods Certain information and footnote disclosures normally included for the annual financial statements prepared in accordance with U.S. GAAP have been condensed or omitted for the interim periods presented. Management believes that the unaudited interim financial statements include all adjustments (which are normal and recurring in nature) necessary to present fairly the financial position of the Company and the results of operations and cash flows for the periods presented. The results of operations for the periods presented are not necessarily indicative of the results that may be expected for the year ending December 31, 2018. Seasonal changes and other conditions can affect the sales volumes of the Company's products. Therefore, the financial results for any interim period do not necessarily indicate the expected results for the year. The financial statements should be read in conjunction with Company's audited consolidated financial statements and the notes thereto for the year ended December 31, 2017 included in the Company's Annual Report on Form 10-K for the fiscal year then ended. The Company has continued to follow the accounting policies set forth in those financial statements. (c) Revenue Disclosure Revenue from the sale of gypsum products is recognized when control of the promised products is transferred to the Company's customers, in an amount that reflects the consideration the Company expects to be entitled to in exchange for those products (the transaction price). A performance obligation is a promise in a contract to transfer a distinct product to a customer and is the unit of account under Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") Topic 606. Control transfers to the customer at a point in time. To indicate the transfer of control, the Company must have a present right to payment, legal title must have passed to the customer and the customer must have the significant risks and rewards of ownership. Generally, the Company satisfies its performance obligations within a number of days from the time the contract is executed. The Company records estimated reductions to revenue for customer programs and incentive offerings, including promotions and other volume-based incentives, in the period in which the sale occurs. Amounts billed to a customer at the transaction price are included in net sales, and costs incurred for shipping and handling are treated as fulfillment costs and are classified as cost of goods sold in the Consolidated Statements of Operations. See Note 17, Segment reporting, for disaggregation of revenue by segment. As of June 30, 2018 , accounts receivables were $43.3 million . The Company had no material contract assets, contract liabilities or deferred contract costs recorded on the Consolidated Balance Sheets as of June 30, 2018 . We do not have any material payment terms as payment is received shortly after the point of sale. (d) Supplemental Cash Flow Disclosure Table 2.1: Certain Cash Transactions and Other Activity For the Six Months Ended June 30, 2018 June 30, 2017 (in thousands) Cash paid during the period for: Interest paid on term loan, net $ 5,241 $ 4,973 Income taxes paid, net 9,334 10,259 Other activity: Amounts in accounts payable for capital expenditures 1,762 1,899 (e) Recent Accounting Pronouncements Accounting Standards Recently Adopted In May 2014, the FASB issued ASU No. 2014-9, "Revenue from Contracts with Customers (Topic 606)," which provides accounting guidance for all revenue arising from contracts with customers and affects all entities that enter into contracts to provide goods or services to their customers. In August 2015, the FASB issued ASU No. 2015-14, "Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date," which deferred the effective date of ASU No. 2014-9 for all entities by one year to annual reporting periods beginning after December 15, 2017. The ASU requires retroactive application on either a full or modified basis. The Company adopted the standard on January 1, 2018 using the modified retrospective approach. Based on evaluation, the Company has concluded it has one revenue stream and the adoption of this new guidance did not have a material impact on its Consolidated Financial Statements. The Company updated its disclosures as required by this ASU. In August 2016, the FASB issued ASU 2016-15, "Classification of Certain Cash Receipts and Cash Payments." This ASU reduces existing diversity in the classification of certain cash receipts and cash payments on the statements of cash flows. ASU 2016-15 is effective for fiscal years beginning after December 15, 2017, and for interim periods within those fiscal years. The adoption of this standard did not have a material impact on the Company's Consolidated Financial Statements. In October 2016, the FASB issued ASU 2016-16, "Intra-Entity Transfers of Assets Other Than Inventory." The new standard requires companies to recognize the income tax effects of intercompany sales or transfers of assets, other than inventory, in the income statement as income tax expense (or benefit) in the period the sales or transfer occurs. The standard requires companies to apply a modified retrospective approach with a cumulative catch-up adjustment to opening retained earnings in the period of adoption. The provisions of this standard are effective for fiscal years beginning after December 15, 2017, and early adoption is permitted. The adoption of this standard did not have a material impact on the Company's Consolidated Financial Statements. Accounting Standards Not Yet Adopted In February 2016, the FASB issued ASU 2016-02, "Leases." ASU 2016-02 requires lessees to recognize a lease liability and a right-of-use asset on the balance sheet. ASU 2016-02 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. The Company is in the process of evaluating the impact of adoption, which is not expected to have a material impact on its Consolidated Financial Statements. In June 2016, the FASB issued ASU 2016-13, "Financial Instruments – Credit Losses: Measurement of Credit Losses on Financial Instruments." This ASU is intended to introduce a revised approach to the recognition and measurement of credit losses, emphasizing an updated model based on expected losses rather than incurred losses. The provisions of this standard are effective for reporting periods beginning after December 15, 2019 and early adoption is permitted. The Company is currently evaluating the impact that this guidance may have on its Consolidated Financial Statements. In August 2017, the FASB issued ASU 2017-12, "Derivatives and Hedging (Topic 815), Targeted Improvements to Accounting for Hedging Activities." This ASU expands an entity's ability to hedge non-financial and financial risk components and reduce complexity in fair value hedges of interest rate risk. The guidance eliminates the requirement to separately measure and report hedge ineffectiveness and generally requires the entire change in the fair value of a hedging instrument to be presented in the same income statement line as the hedged item. The provisions of this standard are effective in 2019 for calendar-year public business entities and in 2020 for all other calendar-year companies. Early adoption of the standard is permitted. The Company is currently evaluating the impact that this guidance may have on its Consolidated Financial Statements. In February 2018, the FASB issued ASU 2018-02, "Income Statement - Reporting Comprehensive Income (Topic 220), Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income." This ASU allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act. The provisions of this standard are effective for reporting periods beginning after December 15, 2018 and early adoption is permitted. The Company is currently evaluating the impact that this guidance may have on its Consolidated Financial Statements. (f) Reclassifications Certain reclassifications of prior year information were made to conform to the 2018 presentation. These reclassifications had no material impact on the Company's Consolidated Financial Statements.

Trade Receivables, Net

Trade Receivables, Net	6 Months Ended
	Jun. 30, 2018
Receivables [Abstract]
Trade Receivables, Net	TRADE RECEIVABLES, NET Table 3: Details of Trade Receivables, Net June 30, 2018 December 31, 2017 (in thousands) Trade receivables, gross $ 44,220 $ 39,577 Allowance for cash discounts and doubtful accounts (906 ) (808 ) Trade receivables, net $ 43,314 $ 38,769 Trade receivables are recorded net of credit memos issued during the normal course of business.

Inventories, Net

Inventories, Net	6 Months Ended
	Jun. 30, 2018
Inventory Disclosure [Abstract]
Inventories, Net	INVENTORIES, NET Table 4: Details of Inventories, Net June 30, 2018 December 31, 2017 (in thousands) Finished products $ 6,961 $ 5,893 Raw materials 13,388 11,663 Supplies and other 7,313 7,326 Inventories, net $ 27,662 $ 24,882

Property, Plant and Equipment,

Property, Plant and Equipment, Net	6 Months Ended
	Jun. 30, 2018
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment, Net	PROPERTY, PLANT AND EQUIPMENT, NET Table 5: Details of Property, Plant and Equipment, Net June 30, 2018 December 31, 2017 (in thousands) Land $ 13,187 $ 13,187 Buildings 115,288 114,051 Plant machinery 285,085 281,786 Mobile equipment 11,700 10,366 Construction in progress 28,154 20,291 Property, plant and equipment, at cost 453,414 439,681 Accumulated depreciation (160,963 ) (145,678 ) Property, plant and equipment, net $ 292,451 $ 294,003 Depreciation expense was $8.3 million and $16.3 million for the three and six months ended June 30, 2018 , respectively, compared to $9.4 million and $17.5 million for the three and six months ended June 30, 2017 , respectively.

Customer Relationships and Othe

Customer Relationships and Other Intangibles, Net	6 Months Ended
	Jun. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Customer Relationships and Other Intangibles, Net	CUSTOMER RELATIONSHIPS AND OTHER INTANGIBLES, NET Table 6.1: Details of Customer Relationships and Other Intangibles, Net June 30, 2018 December 31, 2017 Gross Accumulated Amortization Net Gross Accumulated Amortization Net (in thousands) Customer relationships $ 116,413 $ (61,926 ) $ 54,487 $ 116,711 $ (57,811 ) $ 58,900 Purchased and internally developed software 6,938 (5,174 ) 1,764 6,226 (4,871 ) 1,355 Trademarks 14,802 (4,769 ) 10,033 14,839 (4,287 ) 10,552 Total $ 138,153 $ (71,869 ) $ 66,284 $ 137,776 $ (66,969 ) $ 70,807 Amortization expense was $2.5 million and $5.1 million for the three and six months ended June 30, 2018 , respectively, compared to $3.1 million and $6.3 million for the three and six months ended June 30, 2017 , respectively. Table 6.2: Details of Future Amortization Expense of Customer Relationships and Other Intangibles As of June 30, 2018 (in thousands) July 1, 2018 through December 31, 2018 $ 5,138 2019 8,864 2020 7,951 2021 7,111 2022 6,568 Thereafter 30,652 Total $ 66,284

Investment in Seven Hills

Investment in Seven Hills	6 Months Ended
	Jun. 30, 2018
Equity Method Investments and Joint Ventures [Abstract]
Investment in Seven Hills	INVESTMENT IN SEVEN HILLS The Company is a party with an unaffiliated third party to a paperboard liner venture named Seven Hills Paperboard, LLC ("Seven Hills") that provides the Company with a continuous supply of high-quality recycled paperboard liner to meet its ongoing production requirements. The Company has evaluated the characteristics of its investment and determined that Seven Hills is a variable interest entity, but that it does not have the power to direct the principal activities most impacting the economic performance of Seven Hills, and is thus not the primary beneficiary. As such, the Company accounts for this investment in Seven Hills under the equity method of accounting. Paperboard liner purchased from Seven Hills was $12.9 million and $25.1 million for the three and six months ended June 30, 2018 , respectively, compared to $14.8 million and $26.8 million for the three and six months ended June 30, 2017 , respectively. As of June 30, 2018 , the Company had certain purchase commitments for paper totaling $32.1 million through 2021 .

Accrued and Other Liabilities

Accrued and Other Liabilities	6 Months Ended
	Jun. 30, 2018
Payables and Accruals [Abstract]
Accrued and Other Liabilities	ACCRUED AND OTHER LIABILITIES Table 8: Details of Accrued and Other Liabilities June 30, 2018 December 31, 2017 (in thousands) Employee-related costs $ 6,723 $ 9,258 Income taxes 373 — Other taxes 2,167 938 Other 996 1,744 Accrued and other liabilities $ 10,259 $ 11,940

Debt

Debt	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Debt	DEBT Table 9.1: Details of Debt June 30, 2018 December 31, 2017 (in thousands) Amended and Restated Credit Agreement ( 1 ) $ 270,215 $ 271,573 Less: Original issue discount (net of amortization) (1,510 ) (1,681 ) Less: Debt issuance costs (4,213 ) (4,580 ) Total debt 264,492 265,312 Less: Current portion of long-term debt (1,685 ) (1,702 ) Long-term debt $ 262,807 $ 263,610 (1) As of June 30, 2018 and December 31, 2017, the Amended and Restated Credit Agreement, as amended, had a maturity date of August 18, 2023 and an interest rate of LIBOR (with a 0.75% floor) plus 2.25% . On August 18, 2016, the Company, Continental Building Products Operating Company, LLC and Continental Building Products Canada Inc. and the lenders party thereto and Credit Suisse, as Administrative Agent, entered into an Amended and Restated Credit Agreement amending and restating the Company's First Lien Credit Agreement (the "Amended and Restated Credit Agreement"). The Amended and Restated Credit Agreement provides for a $275 million senior secured first lien term loan facility and a $75 million senior secured revolving credit facility (the "Revolver"), which mature on August 18, 2023 and August 18, 2021, respectively. The interest rate under the Amended and Restated Credit Agreement was a spread over LIBOR of 2.75% and floor of 0.75% . On February 21, 2017 , the Company repriced its term loan under the Amended and Restated Credit Agreement lowering its interest rate by 25 basis points to LIBOR plus 2.50% . Subsequently, on December 6, 2017 , the Company further repriced its term loan under the Amended and Restated Credit Agreement lowering its interest rate by an additional 25 basis points to LIBOR plus 2.25% . The Company may further reduce its interest rate to LIBOR plus 2.00% based on the attainment of a total leverage ratio of 1.1 or better. All other terms and conditions under the Amended and Restated Credit Agreement remained the same. During both the six months ended June 30, 2018 and 2017 , the Company made $1.4 million of scheduled mandatory principal payments. As of June 30, 2018 , the annual effective interest rate, including original issue discount and amortization of debt issuance costs, was 4.8% . There were no amounts outstanding under the Revolver as of June 30, 2018 or 2017 . During the six months ended June 30, 2018 and 2017 the Company did not have any draws under the Revolver. Interest under the Revolver is floating, based on LIBOR plus 2.25% . In addition, the Company pays a facility fee of 50 basis points per annum on the total capacity under the Revolver. Availability under the Revolver as of June 30, 2018 , based on draws and outstanding letters of credit and absence of violations of covenants, was $73.4 million . Table 9.2: Details of Future Minimum Principal Payments Due Under the Amended and Restated Credit Agreement Amount Due (in thousands) July 1, 2018 through December 31, 2018 $ 1,358 2019 2,716 2020 2,716 2021 2,716 2022 2,716 Thereafter 257,993 Total Payments $ 270,215 Under the terms of the Amended and Restated Credit Agreement, the Company is required to comply with certain covenants, including among others, the limitation of indebtedness, limitation on liens, and limitations on certain cash distributions. One single financial covenant governs all of the Company's debt and only applies if the outstanding borrowings of the Revolver plus outstanding letters of credit are greater than $22.5 million as of the end of the quarter. The financial covenant is a total leverage ratio calculation, in which total debt less outstanding cash is divided by adjusted earnings before interest, taxes, depreciation and amortization. As the sum of outstanding borrowings under the Revolver and outstanding letters of credit were less than $22.5 million at June 30, 2018 , the total leverage ratio of no greater than 5.0 under the financial covenant was not applicable at June 30, 2018 . The Company was in compliance with all applicable covenants under the Amended and Restated Credit Agreement as of June 30, 2018 .

Derivative Instruments

Derivative Instruments	6 Months Ended
	Jun. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	DERIVATIVE INSTRUMENTS Commodity Derivative Instruments As of June 30, 2018 , the Company had 2.9 million mmBTUs (millions of British Thermal Units) in aggregate notional amount outstanding natural gas swap contracts to manage commodity price exposures. All of these contracts mature by June 30, 2019 . The Company elected to designate these derivative instruments as cash flow hedges in accordance with ASC 815-20, "Derivatives – Hedging" . No ineffectiveness was recorded on these contracts during the three and six months ended June 30, 2018 and 2017 . Interest Rate Derivative Instrument In September 2016, the Company entered into interest rate swap agreements for a combined notional amount of $100.0 million with a term of four years , which hedged the floating LIBOR on a portion of the term loan under the Amended and Restated Credit Agreement to an average fixed rate of 1.323% and LIBOR floor of 0.75% . The Company elected to designate these interest rate swaps as cash flow hedges for accounting purposes. On March 29, 2018, the Company terminated its interest rate swap agreements that were previously designated as a cash flow hedge and received $3.2 million in cash, the fair value of the swap on the termination date. The unrealized gain at termination remains in accumulated other comprehensive income and will be amortized into interest expense over the life of the original hedged instrument. On the same date, the Company entered into new interest rate swap agreements for a combined notional amount of $100.0 million , which expire on September 30, 2020 and hedge the floating LIBOR on a portion of the term loan under the Amended and Restated Credit Agreement to an average fixed rate of 2.46% and LIBOR floor of 0.75% . The Company elected to designate these interest rate swaps as cash flow hedges for accounting purposes. No ineffectiveness was recorded on these contracts during the three and six months ended June 30, 2018 and 2017 . Table 10.1: Details of Derivatives Fair Value June 30, 2018 December 31, 2017 (in thousands) Assets Interest rate swap $ 414 $ 2,148 Commodity hedges 92 11 Total assets $ 506 $ 2,159 Liabilities Interest rate swap $ — $ — Commodity hedges 40 613 Total liabilities $ 40 $ 613 Table 10.2: Gains/(Losses) on Derivatives For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 2018 2017 2018 2017 Gain/(loss) recognized in Other comprehensive income on derivatives (effective portion), net of tax Gain/(loss) reclassified from Accumulated other comprehensive loss into income (effective portion), net of tax Gain/(loss) recognized in Other comprehensive income on derivatives (effective portion), net of tax Gain/(loss) reclassified from Accumulated other comprehensive loss into income (effective portion), net of tax (in thousands) Interest rate swap 297 (339 ) 139 (29 ) $ 1,268 $ (355 ) $ 209 $ (126 ) Commodity hedges 197 (234 ) (97 ) 54 245 (438 ) (194 ) (89 ) Total $ 494 $ (573 ) $ 42 $ 25 $ 1,513 $ (793 ) $ 15 $ (215 ) Counterparty Risk The Company is exposed to credit losses in the event of nonperformance by the counterparties to the Company's derivative instruments. As of June 30, 2018 , the Company's derivatives were in a $0.5 million net asset position and recorded in Other current assets. All of the Company's counterparties have investment grade credit ratings; accordingly, the Company anticipates that the counterparties will be able to fully satisfy their obligations under the contracts. The Company's agreements outline the conditions upon which it or the counterparties are required to post collateral. As of June 30, 2018 , the Company had no collateral posted with its counterparties related to the derivatives.

Treasury Stock

Treasury Stock	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Treasury Stock	TREASURY STOCK On November 4, 2015 , the Company announced that the Board of Directors approved a new stock repurchase program authorizing the Company to repurchase up to $50 million of its common stock, at such times and prices as determined by management as market conditions warrant, through December 31, 2016 . Pursuant to this authorization, the Company has repurchased shares of its common stock in the open market and in private transactions. During 2017 and 2018 , the Company announced two expansions and extensions of its stock repurchase program. The most recent authorization on February 21, 2018 expanded the program to a total of $300 million and also extended the expiration date to December 31, 2019 . All repurchased shares are held in treasury, reducing the number of shares of common stock outstanding and used in the Company's earnings per share calculation. Table 11: Details of Treasury Stock Activity June 30, 2018 June 30, 2017 Shares Amount (1) Average Share Price (1) Shares Amount (1) Average Share Price (1) (in thousands, except share data) For the Three Months Ended: Beginning Balance 7,319,417 $ 157,907 $ 21.57 4,716,778 $ 93,993 $ 19.93 Repurchases on open market 344,908 10,012 29.03 932,000 22,599 24.25 Ending Balance 7,664,325 $ 167,919 $ 21.91 5,648,778 $ 116,592 $ 20.64 For the Six Months Ended: Beginning Balance 6,788,817 $ 143,357 $ 21.12 4,499,655 $ 88,756 $ 19.73 Repurchases on open market 875,508 24,562 28.05 1,149,123 27,836 24.22 Ending Balance 7,664,325 $ 167,919 $ 21.91 5,648,778 $ 116,592 $ 20.64 ( 1 ) Includes commissions paid for repurchases on open market.

Share-Based Compensation

Share-Based Compensation	6 Months Ended
	Jun. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Compensation	SHARE-BASED COMPENSATION For the three and six months ended June 30, 2018 , the Company recognized share-based compensation expenses of $1.0 million and $1.6 million in expense, respectively, compared to $0.8 million and $1.5 million for the three and six months ended June 30, 2017 , respectively. The expenses related to share-based compensation awards were recorded in selling and administrative expenses. As of June 30, 2018 , there was $6.3 million of total unrecognized compensation cost related to non-vested stock options, restricted stock awards, restricted stock units and performance-based restricted stock units. This cost is expected to be recognized over a weighted average period of 2.4 years .

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Accumulated Other Comprehensive Loss	ACCUMULATED OTHER COMPREHENSIVE LOSS Table 13: Details of Changes in Accumulated Other Comprehensive Loss by Category Foreign currency translation adjustment Net unrealized gain on derivatives, net of tax Total (in thousands) Balance as of December 31, 2017 $ (3,636 ) $ 987 $ (2,649 ) Other comprehensive (loss)/income before reclassifications (795 ) 1,513 718 Amounts reclassified from accumulated other comprehensive loss — (15 ) (15 ) Net current period other comprehensive (loss)/income (795 ) 1,498 703 Balance as of June 30, 2018 $ (4,431 ) $ 2,485 $ (1,946 )

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES The Company’s estimated annual effective tax rate is 22.2% before discrete items. For the six months ended June 30, 2018 , discrete items result in a tax benefit of $0.6 million , consisting of a stock compensation windfall of $0.1 million and a non-recurring benefit of $0.5 million related to re-measurement of deferred taxes resulting from Kentucky tax law change. Due to the timing of the enactment and the complexity involved in applying the provisions of the Tax Cuts and Jobs Act of 2017 (the "Act"), the Company calculated its best estimate of the impact of the Act in its 2017 year end income tax provision in accordance with its understanding of the Act and guidance available as of the date of its Annual Report on Form 10-K for fiscal year 2017 and as a result had recorded a provisional $9.2 million reduction in income tax expense in the fourth quarter of 2017. No adjustment was made to the provisional amount as a result of additional information obtained for the six months ended June 30, 2018 . The accounting is expected to be complete when the 2017 U.S. federal and state corporate income tax returns are filed in late 2018. The Company is subject to audit examinations at federal, state and local levels by tax authorities in those jurisdictions. In addition, the Canadian operations are subject to audit examinations at federal and provincial levels by tax authorities in those jurisdictions. The tax matters challenged by the tax authorities are typically complex; therefore, the ultimate outcome of any challenges would be subject to uncertainty. The Company has not identified any issues that did not meet the recognition threshold or would be impacted by the measurement provisions of the uncertain tax position guidance.

Earnings Per Share

Earnings Per Share	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Earnings Per Share	EARNINGS PER SHARE The following table shows the weighted average number of shares used in computing earnings per share and the effect on the weighted average number of shares of potentially dilutive securities. Potentially dilutive common stock has no effect on income available to common stockholders. For the three and six months ended June 30, 2018 , zero and approximately 31,000 share-based compensation awards, respectively, were excluded from the weighted average shares outstanding because their impact would be anti-dilutive in the computation of dilutive earnings per share. Awards excluded for the same periods in 2017 were approximately 1,000 and 43,000 , respectively. Table 15: Details of Basic and Dilutive Earnings Per Share For the Three Months Ended For the Six Months Ended June 30, 2018 June 30, 2017 June 30, 2018 June 30, 2017 (dollars in thousands, except for per share amounts) Net income $ 21,895 $ 12,398 $ 35,541 $ 24,625 Weighted average number of shares outstanding - basic 36,879,774 39,125,571 37,154,750 39,349,674 Effect of dilutive securities: Restricted stock awards — 5,880 1,755 7,971 Restricted stock units 56,188 39,988 64,100 57,169 Performance restricted stock units 63,799 17,837 66,654 17,180 Stock options 28,236 20,943 27,688 22,934 Total effect of dilutive securities 148,223 84,648 160,197 105,254 Weighted average number of shares outstanding - diluted 37,027,997 39,210,219 37,314,947 39,454,928 Basic earnings per share $ 0.59 $ 0.32 $ 0.96 $ 0.63 Diluted earnings per share $ 0.59 $ 0.32 $ 0.95 $ 0.62

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES Commitments The Company leases certain buildings and equipment. The Company's facility and equipment leases may provide for escalations of rent or rent abatements and payment of pro rata portions of building operating expenses. Minimum lease payments are recognized on a straight-line basis over the minimum lease term. The total expenses under operating leases for the three and six months ended June 30, 2018 were $0.8 million and $1.6 million , respectively, compared to $0.9 million and $1.7 million for the same periods in 2017 , respectively. The Company also has non-capital purchase commitments that primarily relate to gas, gypsum, paper and other raw materials. The total amounts purchased under such commitments were $23.3 million and $43.5 million for the three and six months ended June 30, 2018 , respectively, compared to $21.7 million and $42.8 million for the three and six months ended June 30, 2017 , respectively. Table 16: Details of Future Minimum Lease Payments Due Under Noncancellable Operating Leases and Purchase Commitments Future Minimum Lease Payments Purchase Commitments (in thousands) July 1, 2018 - December 31, 2018 $ 360 $ 14,975 2019 1,658 28,178 2020 48 27,054 2021 — 8,828 2022 — 5,410 2023 — 5,572 Thereafter — 53,621 Total $ 2,066 $ 143,638 Contingent obligations Under certain circumstances, the Company provides letters of credit related to its natural gas and other supply purchases. As of June 30, 2018 and December 31, 2017 , the Company had outstanding letters of credit of approximately $1.6 million . Legal Matters In the ordinary course of business, the Company executes contracts involving indemnifications standard in the industry. These indemnifications might include claims relating to any of the following: environmental and tax matters; intellectual property rights; governmental regulations and employment-related matters; customer, supplier, and other commercial contractual relationships; and financial matters. While the maximum amount to which the Company may be exposed under such agreements cannot be estimated, it is the opinion of management that these guarantees and indemnifications are not expected to have a material adverse effect on the Company's financial condition, results of operations or liquidity. In the ordinary course of business, the Company is involved in certain legal actions and claims, including proceedings under laws and regulations relating to environmental and other matters. Because such matters are subject to many uncertainties and the outcomes are not predictable with assurance, the total liability for these legal actions and claims cannot be determined with certainty. When the Company determines that it is probable that a liability for environmental matters, legal actions or other contingencies has been incurred and the amount of the loss is reasonably estimable, an estimate of the costs to be incurred is recorded as a liability in the financial statements. As of June 30, 2018 and December 31, 2017 , such liabilities were not expected to have a material adverse effect on the Company's financial condition, results of operations or liquidity. While management believes its accruals for such liabilities are adequate, the Company may incur costs in excess of the amounts provided. Although the ultimate amount of liability that may result from these matters or actions is not ascertainable, any amounts exceeding the recorded accruals are not expected to have a material adverse effect on the Company's financial condition, results of operations or liquidity.

Segment Reporting

Segment Reporting	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Segment Reporting	SEGMENT REPORTING Segment information is presented in accordance with ASC 280, Segment Reporting, which establishes standards for reporting information about operating segments. It also establishes standards for related disclosures about products and geographic areas. The Company's primary reportable segment is wallboard, which represented approximately 97.4% and 97.1% of the Company's revenues for the three and six months ended June 30, 2018 , respectively, compared to 97.2% and 96.9% of the Company's revenues for the three and six months ended June 30, 2017 , respectively. This segment produces wallboard for the commercial and residential construction sectors. The Company also manufactures finishing products, which complement the Company's full range of wallboard products. Revenues from the major products sold to external customers include gypsum wallboard and finishing products. The Company's two geographic areas consist of the United States and Canada for which it reports net sales, fixed assets and total assets. The Company evaluates operating performance based on profit or loss from operations before certain adjustments as shown below. Revenues are attributed to geographic areas based on the location of the customer generating the revenue. The Company did not provide asset information by segment as its Chief Operating Decision Maker does not use such information for purposes of allocating resources and assessing segment performance. Table 17.1: Segment Reporting For the Three Months Ended For the Six Months Ended June 30, 2018 June 30, 2017 June 30, 2018 June 30, 2017 (in thousands) Net Sales: Wallboard $ 135,667 $ 117,194 $ 248,638 $ 233,670 Other 3,601 3,436 7,432 7,575 Total net sales $ 139,268 $ 120,630 $ 256,070 $ 241,245 Operating Income: Wallboard 31,122 21,819 $ 52,152 $ 43,411 Other (562 ) (199 ) (830 ) (104 ) Total operating income $ 30,560 $ 21,620 $ 51,322 $ 43,307 Adjustments: Interest expense (2,694 ) (3,062 ) $ (5,414 ) $ (5,978 ) (Losses)/income from equity investment (391 ) 345 (755 ) 175 Other expense, net (87 ) (135 ) (227 ) (779 ) Income before provision for income taxes $ 27,388 $ 18,768 $ 44,926 $ 36,725 Depreciation and Amortization: Wallboard 10,411 12,177 $ 20,717 $ 23,199 Other 394 297 669 561 Total depreciation and amortization $ 10,805 $ 12,474 $ 21,386 $ 23,760 Table 17.2: Details of Net Sales By Geographic Region For the Three Months Ended For the Six Months Ended June 30, 2018 June 30, 2017 June 30, 2018 June 30, 2017 (in thousands) United States $ 132,513 $ 113,665 $ 242,488 $ 224,051 Canada 6,755 6,965 13,582 17,194 Net sales $ 139,268 $ 120,630 $ 256,070 $ 241,245 Table 17.3: Details of Assets By Geographic Region Fixed Assets Total Assets June 30, 2018 December 31, 2017 June 30, 2018 December 31, 2017 (in thousands) United States $ 289,099 $ 290,324 $ 633,576 $ 622,836 Canada 3,352 3,679 17,979 19,098 Total $ 292,451 $ 294,003 $ 651,555 $ 641,934

Fair Value Disclosures

Fair Value Disclosures	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Disclosures	FAIR VALUE DISCLOSURES The Company estimates the fair value of its debt by discounting the future cash flows of each instrument using estimated market rates of debt instruments with similar maturities and credit profiles. These inputs are classified as Level 3 within the fair value hierarchy. As of June 30, 2018 and December 31, 2017 , the carrying value reported in the consolidated balance sheet for the Company's notes payable approximated its fair value. The only assets or liabilities the Company had at June 30, 2018 that are recorded at fair value on a recurring basis are the natural gas hedges and interest rate swaps. Generally, the Company obtains its Level 2 pricing inputs from its counterparties. Substantially all of these assumptions are observable in the marketplace throughout the full term of the instrument, can be derived from observable data or are supported by observable levels at which transactions are executed in the marketplace. Assets and liabilities that are measured at fair value on a non-recurring basis include intangible assets and goodwill. These items are recognized at fair value when they are considered to be impaired. There were no fair value adjustments for assets and liabilities measured on a non-recurring basis. The Company discloses fair value information about financial instruments for which it is practicable to estimate that value. Table 18.1: Fair Value Hierarchy - 2018 As of June 30, 2018 Level 1 Level 2 Level 3 Balance (in thousands) Asset Interest rate swap $ — $ 414 $ — $ 414 Commodity derivatives — 92 — 92 Total assets $ — $ 506 $ — $ 506 Liabilities Interest rate swap $ — $ — $ — $ — Commodity derivatives — 40 — 40 Total liabilities $ — $ 40 $ — $ 40 Table 18.2: Fair Value Hierarchy - 2017 As of December 31, 2017 Level 1 Level 2 Level 3 Balance (in thousands) Asset Interest rate swap $ — $ 2,148 $ — $ 2,148 Commodity derivatives — 11 — 11 Total assets $ — $ 2,159 $ — $ 2,159 Liabilities Interest rate swap $ — $ — $ — $ — Commodity derivatives — 613 — 613 Total liabilities $ — $ 613 $ — $ 613

Significant Accounting Polici25

Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements for the Company have been prepared in accordance with accounting principles generally accepted in the United States ("U.S. GAAP"). The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany transactions have been eliminated.
Revenue Recognition	Revenue Disclosure Revenue from the sale of gypsum products is recognized when control of the promised products is transferred to the Company's customers, in an amount that reflects the consideration the Company expects to be entitled to in exchange for those products (the transaction price). A performance obligation is a promise in a contract to transfer a distinct product to a customer and is the unit of account under Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") Topic 606. Control transfers to the customer at a point in time. To indicate the transfer of control, the Company must have a present right to payment, legal title must have passed to the customer and the customer must have the significant risks and rewards of ownership. Generally, the Company satisfies its performance obligations within a number of days from the time the contract is executed. The Company records estimated reductions to revenue for customer programs and incentive offerings, including promotions and other volume-based incentives, in the period in which the sale occurs. Amounts billed to a customer at the transaction price are included in net sales, and costs incurred for shipping and handling are treated as fulfillment costs and are classified as cost of goods sold in the Consolidated Statements of Operations. See Note 17, Segment reporting, for disaggregation of revenue by segment.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Accounting Standards Recently Adopted In May 2014, the FASB issued ASU No. 2014-9, "Revenue from Contracts with Customers (Topic 606)," which provides accounting guidance for all revenue arising from contracts with customers and affects all entities that enter into contracts to provide goods or services to their customers. In August 2015, the FASB issued ASU No. 2015-14, "Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date," which deferred the effective date of ASU No. 2014-9 for all entities by one year to annual reporting periods beginning after December 15, 2017. The ASU requires retroactive application on either a full or modified basis. The Company adopted the standard on January 1, 2018 using the modified retrospective approach. Based on evaluation, the Company has concluded it has one revenue stream and the adoption of this new guidance did not have a material impact on its Consolidated Financial Statements. The Company updated its disclosures as required by this ASU. In August 2016, the FASB issued ASU 2016-15, "Classification of Certain Cash Receipts and Cash Payments." This ASU reduces existing diversity in the classification of certain cash receipts and cash payments on the statements of cash flows. ASU 2016-15 is effective for fiscal years beginning after December 15, 2017, and for interim periods within those fiscal years. The adoption of this standard did not have a material impact on the Company's Consolidated Financial Statements. In October 2016, the FASB issued ASU 2016-16, "Intra-Entity Transfers of Assets Other Than Inventory." The new standard requires companies to recognize the income tax effects of intercompany sales or transfers of assets, other than inventory, in the income statement as income tax expense (or benefit) in the period the sales or transfer occurs. The standard requires companies to apply a modified retrospective approach with a cumulative catch-up adjustment to opening retained earnings in the period of adoption. The provisions of this standard are effective for fiscal years beginning after December 15, 2017, and early adoption is permitted. The adoption of this standard did not have a material impact on the Company's Consolidated Financial Statements. Accounting Standards Not Yet Adopted In February 2016, the FASB issued ASU 2016-02, "Leases." ASU 2016-02 requires lessees to recognize a lease liability and a right-of-use asset on the balance sheet. ASU 2016-02 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. The Company is in the process of evaluating the impact of adoption, which is not expected to have a material impact on its Consolidated Financial Statements. In June 2016, the FASB issued ASU 2016-13, "Financial Instruments – Credit Losses: Measurement of Credit Losses on Financial Instruments." This ASU is intended to introduce a revised approach to the recognition and measurement of credit losses, emphasizing an updated model based on expected losses rather than incurred losses. The provisions of this standard are effective for reporting periods beginning after December 15, 2019 and early adoption is permitted. The Company is currently evaluating the impact that this guidance may have on its Consolidated Financial Statements. In August 2017, the FASB issued ASU 2017-12, "Derivatives and Hedging (Topic 815), Targeted Improvements to Accounting for Hedging Activities." This ASU expands an entity's ability to hedge non-financial and financial risk components and reduce complexity in fair value hedges of interest rate risk. The guidance eliminates the requirement to separately measure and report hedge ineffectiveness and generally requires the entire change in the fair value of a hedging instrument to be presented in the same income statement line as the hedged item. The provisions of this standard are effective in 2019 for calendar-year public business entities and in 2020 for all other calendar-year companies. Early adoption of the standard is permitted. The Company is currently evaluating the impact that this guidance may have on its Consolidated Financial Statements. In February 2018, the FASB issued ASU 2018-02, "Income Statement - Reporting Comprehensive Income (Topic 220), Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income." This ASU allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act. The provisions of this standard are effective for reporting periods beginning after December 15, 2018 and early adoption is permitted. The Company is currently evaluating the impact that this guidance may have on its Consolidated Financial Statements.
Reclassifications	Reclassifications Certain reclassifications of prior year information were made to conform to the 2018 presentation. These reclassifications had no material impact on the Company's Consolidated Financial Statements.

Significant Accounting Polici26

Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2017
Accounting Policies [Abstract]
Schedule of Cash Flow, Supplemental Disclosures	Supplemental Cash Flow Disclosure Table 2.1: Certain Cash Transactions and Other Activity For the Six Months Ended June 30, 2018 June 30, 2017 (in thousands) Cash paid during the period for: Interest paid on term loan, net $ 5,241 $ 4,973 Income taxes paid, net 9,334 10,259 Other activity: Amounts in accounts payable for capital expenditures 1,762 1,899

Trade Receivables, Net (Tables)

Trade Receivables, Net (Tables)	6 Months Ended
	Jun. 30, 2018
Receivables [Abstract]
Detail of Receivables, Net	Table 3: Details of Trade Receivables, Net June 30, 2018 December 31, 2017 (in thousands) Trade receivables, gross $ 44,220 $ 39,577 Allowance for cash discounts and doubtful accounts (906 ) (808 ) Trade receivables, net $ 43,314 $ 38,769

Inventories, Net (Tables)

Inventories, Net (Tables)	6 Months Ended
	Jun. 30, 2018
Inventory Disclosure [Abstract]
Composition of Inventories	Table 4: Details of Inventories, Net June 30, 2018 December 31, 2017 (in thousands) Finished products $ 6,961 $ 5,893 Raw materials 13,388 11,663 Supplies and other 7,313 7,326 Inventories, net $ 27,662 $ 24,882

Property, Plant and Equipment29

Property, Plant and Equipment, Net (Tables)	6 Months Ended
	Jun. 30, 2018
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment Details	Table 5: Details of Property, Plant and Equipment, Net June 30, 2018 December 31, 2017 (in thousands) Land $ 13,187 $ 13,187 Buildings 115,288 114,051 Plant machinery 285,085 281,786 Mobile equipment 11,700 10,366 Construction in progress 28,154 20,291 Property, plant and equipment, at cost 453,414 439,681 Accumulated depreciation (160,963 ) (145,678 ) Property, plant and equipment, net $ 292,451 $ 294,003

Customer Relationships and Ot30

Customer Relationships and Other Intangibles, Net (Tables)	6 Months Ended
	Jun. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Details of Customer Relationships and Other Intangibles, Net	Table 6.1: Details of Customer Relationships and Other Intangibles, Net June 30, 2018 December 31, 2017 Gross Accumulated Amortization Net Gross Accumulated Amortization Net (in thousands) Customer relationships $ 116,413 $ (61,926 ) $ 54,487 $ 116,711 $ (57,811 ) $ 58,900 Purchased and internally developed software 6,938 (5,174 ) 1,764 6,226 (4,871 ) 1,355 Trademarks 14,802 (4,769 ) 10,033 14,839 (4,287 ) 10,552 Total $ 138,153 $ (71,869 ) $ 66,284 $ 137,776 $ (66,969 ) $ 70,807
Future Amortization Expense of Customer Relationships and Other Intangibles	Table 6.2: Details of Future Amortization Expense of Customer Relationships and Other Intangibles As of June 30, 2018 (in thousands) July 1, 2018 through December 31, 2018 $ 5,138 2019 8,864 2020 7,951 2021 7,111 2022 6,568 Thereafter 30,652 Total $ 66,284

Accrued and Other Liabilities (

Accrued and Other Liabilities (Tables)	6 Months Ended
	Jun. 30, 2018
Payables and Accruals [Abstract]
Details of Accrued and Other Liabilities	Table 8: Details of Accrued and Other Liabilities June 30, 2018 December 31, 2017 (in thousands) Employee-related costs $ 6,723 $ 9,258 Income taxes 373 — Other taxes 2,167 938 Other 996 1,744 Accrued and other liabilities $ 10,259 $ 11,940

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Details of Debt	Table 9.1: Details of Debt June 30, 2018 December 31, 2017 (in thousands) Amended and Restated Credit Agreement ( 1 ) $ 270,215 $ 271,573 Less: Original issue discount (net of amortization) (1,510 ) (1,681 ) Less: Debt issuance costs (4,213 ) (4,580 ) Total debt 264,492 265,312 Less: Current portion of long-term debt (1,685 ) (1,702 ) Long-term debt $ 262,807 $ 263,610
Future Minimum Principal Payments Due Under the Credit Agreements	Table 9.2: Details of Future Minimum Principal Payments Due Under the Amended and Restated Credit Agreement Amount Due (in thousands) July 1, 2018 through December 31, 2018 $ 1,358 2019 2,716 2020 2,716 2021 2,716 2022 2,716 Thereafter 257,993 Total Payments $ 270,215

Derivative Instruments (Tables)

Derivative Instruments (Tables)	6 Months Ended
	Jun. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	Table 10.1: Details of Derivatives Fair Value June 30, 2018 December 31, 2017 (in thousands) Assets Interest rate swap $ 414 $ 2,148 Commodity hedges 92 11 Total assets $ 506 $ 2,159 Liabilities Interest rate swap $ — $ — Commodity hedges 40 613 Total liabilities $ 40 $ 613
Derivative Instruments, Gain (Loss)	Table 10.2: Gains/(Losses) on Derivatives For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 2018 2017 2018 2017 Gain/(loss) recognized in Other comprehensive income on derivatives (effective portion), net of tax Gain/(loss) reclassified from Accumulated other comprehensive loss into income (effective portion), net of tax Gain/(loss) recognized in Other comprehensive income on derivatives (effective portion), net of tax Gain/(loss) reclassified from Accumulated other comprehensive loss into income (effective portion), net of tax (in thousands) Interest rate swap 297 (339 ) 139 (29 ) $ 1,268 $ (355 ) $ 209 $ (126 ) Commodity hedges 197 (234 ) (97 ) 54 245 (438 ) (194 ) (89 ) Total $ 494 $ (573 ) $ 42 $ 25 $ 1,513 $ (793 ) $ 15 $ (215 )

Treasury Stock (Tables)

Treasury Stock (Tables)	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Treasury Stock Activity	All repurchased shares are held in treasury, reducing the number of shares of common stock outstanding and used in the Company's earnings per share calculation. Table 11: Details of Treasury Stock Activity June 30, 2018 June 30, 2017 Shares Amount (1) Average Share Price (1) Shares Amount (1) Average Share Price (1) (in thousands, except share data) For the Three Months Ended: Beginning Balance 7,319,417 $ 157,907 $ 21.57 4,716,778 $ 93,993 $ 19.93 Repurchases on open market 344,908 10,012 29.03 932,000 22,599 24.25 Ending Balance 7,664,325 $ 167,919 $ 21.91 5,648,778 $ 116,592 $ 20.64 For the Six Months Ended: Beginning Balance 6,788,817 $ 143,357 $ 21.12 4,499,655 $ 88,756 $ 19.73 Repurchases on open market 875,508 24,562 28.05 1,149,123 27,836 24.22 Ending Balance 7,664,325 $ 167,919 $ 21.91 5,648,778 $ 116,592 $ 20.64 ( 1 ) Includes commissions paid for repurchases on open market.

Accumulated Other Comprehensi35

Accumulated Other Comprehensive Loss (Tables)	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Changes in Accumulated Other Comprehensive (Loss)/Income by Category	Table 13: Details of Changes in Accumulated Other Comprehensive Loss by Category Foreign currency translation adjustment Net unrealized gain on derivatives, net of tax Total (in thousands) Balance as of December 31, 2017 $ (3,636 ) $ 987 $ (2,649 ) Other comprehensive (loss)/income before reclassifications (795 ) 1,513 718 Amounts reclassified from accumulated other comprehensive loss — (15 ) (15 ) Net current period other comprehensive (loss)/income (795 ) 1,498 703 Balance as of June 30, 2018 $ (4,431 ) $ 2,485 $ (1,946 )

Earnings Per Share (Tables)

Earnings Per Share (Tables)	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Basic and Dilutive Earnings Per Share	The following table shows the weighted average number of shares used in computing earnings per share and the effect on the weighted average number of shares of potentially dilutive securities. Potentially dilutive common stock has no effect on income available to common stockholders. For the three and six months ended June 30, 2018 , zero and approximately 31,000 share-based compensation awards, respectively, were excluded from the weighted average shares outstanding because their impact would be anti-dilutive in the computation of dilutive earnings per share. Awards excluded for the same periods in 2017 were approximately 1,000 and 43,000 , respectively. Table 15: Details of Basic and Dilutive Earnings Per Share For the Three Months Ended For the Six Months Ended June 30, 2018 June 30, 2017 June 30, 2018 June 30, 2017 (dollars in thousands, except for per share amounts) Net income $ 21,895 $ 12,398 $ 35,541 $ 24,625 Weighted average number of shares outstanding - basic 36,879,774 39,125,571 37,154,750 39,349,674 Effect of dilutive securities: Restricted stock awards — 5,880 1,755 7,971 Restricted stock units 56,188 39,988 64,100 57,169 Performance restricted stock units 63,799 17,837 66,654 17,180 Stock options 28,236 20,943 27,688 22,934 Total effect of dilutive securities 148,223 84,648 160,197 105,254 Weighted average number of shares outstanding - diluted 37,027,997 39,210,219 37,314,947 39,454,928 Basic earnings per share $ 0.59 $ 0.32 $ 0.96 $ 0.63 Diluted earnings per share $ 0.59 $ 0.32 $ 0.95 $ 0.62

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Future Minimum Lease Payments Due Under Non-Cancelable Operating Leases and Purchase Commitments by Year	Table 16: Details of Future Minimum Lease Payments Due Under Noncancellable Operating Leases and Purchase Commitments Future Minimum Lease Payments Purchase Commitments (in thousands) July 1, 2018 - December 31, 2018 $ 360 $ 14,975 2019 1,658 28,178 2020 48 27,054 2021 — 8,828 2022 — 5,410 2023 — 5,572 Thereafter — 53,621 Total $ 2,066 $ 143,638

Segment Reporting (Tables)

Segment Reporting (Tables)	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Segment Reporting	Table 17.1: Segment Reporting For the Three Months Ended For the Six Months Ended June 30, 2018 June 30, 2017 June 30, 2018 June 30, 2017 (in thousands) Net Sales: Wallboard $ 135,667 $ 117,194 $ 248,638 $ 233,670 Other 3,601 3,436 7,432 7,575 Total net sales $ 139,268 $ 120,630 $ 256,070 $ 241,245 Operating Income: Wallboard 31,122 21,819 $ 52,152 $ 43,411 Other (562 ) (199 ) (830 ) (104 ) Total operating income $ 30,560 $ 21,620 $ 51,322 $ 43,307 Adjustments: Interest expense (2,694 ) (3,062 ) $ (5,414 ) $ (5,978 ) (Losses)/income from equity investment (391 ) 345 (755 ) 175 Other expense, net (87 ) (135 ) (227 ) (779 ) Income before provision for income taxes $ 27,388 $ 18,768 $ 44,926 $ 36,725 Depreciation and Amortization: Wallboard 10,411 12,177 $ 20,717 $ 23,199 Other 394 297 669 561 Total depreciation and amortization $ 10,805 $ 12,474 $ 21,386 $ 23,760
Net Sales By Geographic Region	Table 17.2: Details of Net Sales By Geographic Region For the Three Months Ended For the Six Months Ended June 30, 2018 June 30, 2017 June 30, 2018 June 30, 2017 (in thousands) United States $ 132,513 $ 113,665 $ 242,488 $ 224,051 Canada 6,755 6,965 13,582 17,194 Net sales $ 139,268 $ 120,630 $ 256,070 $ 241,245
Assets By Geographic Region	Table 17.3: Details of Assets By Geographic Region Fixed Assets Total Assets June 30, 2018 December 31, 2017 June 30, 2018 December 31, 2017 (in thousands) United States $ 289,099 $ 290,324 $ 633,576 $ 622,836 Canada 3,352 3,679 17,979 19,098 Total $ 292,451 $ 294,003 $ 651,555 $ 641,934

Fair Value Disclosures (Tables)

Fair Value Disclosures (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	Table 18.1: Fair Value Hierarchy - 2018 As of June 30, 2018 Level 1 Level 2 Level 3 Balance (in thousands) Asset Interest rate swap $ — $ 414 $ — $ 414 Commodity derivatives — 92 — 92 Total assets $ — $ 506 $ — $ 506 Liabilities Interest rate swap $ — $ — $ — $ — Commodity derivatives — 40 — 40 Total liabilities $ — $ 40 $ — $ 40 Table 18.2: Fair Value Hierarchy - 2017 As of December 31, 2017 Level 1 Level 2 Level 3 Balance (in thousands) Asset Interest rate swap $ — $ 2,148 $ — $ 2,148 Commodity derivatives — 11 — 11 Total assets $ — $ 2,159 $ — $ 2,159 Liabilities Interest rate swap $ — $ — $ — $ — Commodity derivatives — 613 — 613 Total liabilities $ — $ 613 $ — $ 613

Background and Nature of Oper40

Background and Nature of Operations - Description of Business and Acquisition (Detail) $ in Millions	Aug. 30, 2013USD ($)	Jun. 30, 2018facility
Lone Star Fund VIII (U.S.), L.P. | Lafarge N.A.
Business Acquisition [Line Items]
Total purchase price | $	$ 703
Wallboard
Business Acquisition [Line Items]
Number of operating facilities (facility)		3
Joint Compound
Business Acquisition [Line Items]
Number of operating facilities (facility)		1

Significant Accounting Polici41

Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Accounts receivable	$ 43,314	$ 38,769

Significant Accounting Polici42

Significant Accounting Policies - Certain Cash and Non-Cash Transactions (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Accounting Policies [Abstract]
Interest paid on term loan, net	$ 5,241	$ 4,973
Income taxes paid, net	9,334	10,259
Other activity:	$ 1,762	$ 1,899

Trade Receivables, Net - Detail

Trade Receivables, Net - Detail of Receivables, Net (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Receivables [Abstract]
Trade receivables, gross	$ 44,220	$ 39,577
Allowance for cash discounts and doubtful accounts	(906)	(808)
Trade receivables, net	$ 43,314	$ 38,769

Inventories, Net (Detail)

Inventories, Net (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Finished products	$ 6,961	$ 5,893
Raw materials	13,388	11,663
Supplies and other	7,313	7,326
Inventories, net	$ 27,662	$ 24,882

Property, Plant and Equipment45

Property, Plant and Equipment, Net - Property, Plant and Equipment Details (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	$ 453,414	$ 439,681
Accumulated depreciation	(160,963)	(145,678)
Property, plant and equipment, net	292,451	294,003
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	13,187	13,187
Buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	115,288	114,051
Plant machinery
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	285,085	281,786
Mobile equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	11,700	10,366
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	$ 28,154	$ 20,291

Property, Plant and Equipment46

Property, Plant and Equipment, Net - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 8.3	$ 9.4	$ 16.3	$ 17.5

Investment in Seven Hills - Add

Investment in Seven Hills - Additional Information (Detail) - Seven Hills - Variable Interest Entity, Not Primary Beneficiary - Equity Method Investee - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Schedule of Equity Method Investments [Line Items]
Cost of paperboard	$ 12.9	$ 14.8	$ 25.1	$ 26.8
Purchase commitments			$ 32.1

Customer Relationships and Ot48

Customer Relationships and Other Intangibles, Net - Details of Customer Relationships and Other Intangibles, Net (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross	$ 138,153	$ 137,776
Accumulated Amortization	(71,869)	(66,969)
Net	66,284	70,807
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross	116,413	116,711
Accumulated Amortization	(61,926)	(57,811)
Net	54,487	58,900
Purchased and internally developed software
Finite-Lived Intangible Assets [Line Items]
Gross	6,938	6,226
Accumulated Amortization	(5,174)	(4,871)
Net	1,764	1,355
Trademarks
Finite-Lived Intangible Assets [Line Items]
Gross	14,802	14,839
Accumulated Amortization	(4,769)	(4,287)
Net	$ 10,033	$ 10,552

Customer Relationships and Ot49

Customer Relationships and Other Intangibles, Net - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense	$ 2.5	$ 3.1	$ 5.1	$ 6.3

Customer Relationships and Ot50

Customer Relationships and Other Intangibles, Net - Future Amortization Expense of Customer Relationships and Other Intangibles (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
July 1, 2018 through December 31, 2018	$ 5,138
2,019	8,864
2,020	7,951
2,021	7,111
2,022	6,568
Thereafter	30,652
Net	$ 66,284	$ 70,807

Accrued and Other Liabilities51

Accrued and Other Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Employee-related costs	$ 6,723	$ 9,258
Income taxes	373	0
Other taxes	2,167	938
Other	996	1,744
Accrued and other liabilities	$ 10,259	$ 11,940

Debt - Details of Debt (Detail)

Debt - Details of Debt (Detail) - USD ($) $ in Thousands	Aug. 18, 2016	Jun. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Amended and Restated Credit Agreement		$ 270,215
Less: Original issue discount (net of amortization)		(1,510)	$ (1,681)
Less: Debt issuance costs		(4,213)	(4,580)
Total debt		264,492	265,312
Less: Current portion of long-term debt		(1,685)	(1,702)
Long-term debt		262,807	263,610
Term Loan Facility | First Lien Credit Agreement
Debt Instrument [Line Items]
Amended and Restated Credit Agreement		$ 270,215	$ 271,573
Term Loan Facility | First Lien Credit Agreement | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Floor rate	0.75%	0.75%
Debt, variable interest rate (as a percent)	2.75%	2.25%

Debt - Additional Information (

Debt - Additional Information (Detail)	Dec. 06, 2017	Feb. 21, 2017	Aug. 18, 2016USD ($)	Jun. 30, 2018USD ($)covenant	Jun. 30, 2017USD ($)	Dec. 31, 2017USD ($)
Debt Instrument [Line Items]
Scheduled mandatory principal payments				$ 1,400,000	$ 1,400,000
First Lien Credit Agreement
Debt Instrument [Line Items]
Number of covenants | covenant				1
Debt covenant trigger, line of credit facility amount less letters of credit threshold				$ 22,500,000
First Lien Credit Agreement | Maximum
Debt Instrument [Line Items]
Leverage ratio (no greater than)				5
Amended and Restated Credit Agreement
Debt Instrument [Line Items]
Decrease in basis spread, percentage	25.00%	0.25%
Leverage ratio (no greater than)	1.1
Amended and Restated Credit Agreement | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt, variable interest rate (as a percent)	2.25%	2.50%
Debt, variable interest rate if leverage ratio met	2.00%
Term Loan Facility | First Lien Credit Agreement
Debt Instrument [Line Items]
Debt principal amount			$ 275,000,000
Effective interest rate				4.80%
Term Loan Facility | First Lien Credit Agreement | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt, variable interest rate (as a percent)			2.75%	2.25%
Floor rate			0.75%	0.75%
Line of Credit | First Lien Credit Agreement | Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility borrowing capacity			$ 75,000,000
Debt, variable interest rate (as a percent)				2.25%
Outstanding amount				$ 0		$ 0
Proceeds from line of credit				$ 0	$ 0
Facility fee, basis points				0.50%
Remaining outstanding				$ 73,400,000

Debt - Future Minimum Principal

Debt - Future Minimum Principal Payments Due Under the Credit Agreements (Detail) $ in Thousands	Jun. 30, 2018USD ($)
Long-term Debt, Fiscal Year Maturity [Abstract]
July 1, 2018 through December 31, 2018	$ 1,358
2,019	2,716
2,018	2,716
2,020	2,716
2,021	2,716
Thereafter	257,993
Total Payments	$ 270,215

Derivative Instruments - Additi

Derivative Instruments - Additional Information (Detail)	Mar. 29, 2018USD ($)	Sep. 30, 2016USD ($)	Jun. 30, 2018USD ($)MMBTU
Derivative [Line Items]
Proceeds from derivative hedges	$ 3,200,000
Derivatives, net liability position			$ 500,000
Collateral posted with counterparties related to derivatives			$ 0
Natural Gas Swap | Cash Flow Hedging | Designated as Hedging Instrument
Derivative [Line Items]
Aggregate notional amount outstanding (in mmBTUs) | MMBTU			2,905,000
Interest rate swap | Cash Flow Hedging | Designated as Hedging Instrument
Derivative [Line Items]
Aggregate notional amount outstanding	$ 100,000,000	$ 100,000,000
Derivative instrument term (not beyond)		4 years
Average fixed rate (as a percent)	2.46%	1.323%
Interest rate swap | Cash Flow Hedging | Designated as Hedging Instrument | London Interbank Offered Rate (LIBOR)
Derivative [Line Items]
Floor rate (as a percent)	0.75%	0.75%

Derivative Instruments - Deriva

Derivative Instruments - Derivatives at Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Derivative [Line Items]
Derivative asset	$ 506	$ 2,159
Derivative liability	40	613
Interest rate swap
Derivative [Line Items]
Derivative asset	414	2,148
Derivative liability	0	0
Commodity derivatives
Derivative [Line Items]
Derivative asset	92	11
Derivative liability	$ 40	$ 613

Derivative Instruments - Gains

Derivative Instruments - Gains (losses) on derivatives (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(loss) recognized in Other comprehensive income on derivatives (effective portion), net of tax	$ 494	$ (573)	$ 1,513	$ (793)
Gain/(loss) reclassified from Accumulated other comprehensive loss into income (effective portion), net of tax	42	25	15	(215)
Interest rate swap
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(loss) recognized in Other comprehensive income on derivatives (effective portion), net of tax	297	(339)	1,268	(355)
Gain/(loss) reclassified from Accumulated other comprehensive loss into income (effective portion), net of tax	139	(29)	209	(126)
Commodity derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(loss) recognized in Other comprehensive income on derivatives (effective portion), net of tax	197	(234)	245	(438)
Gain/(loss) reclassified from Accumulated other comprehensive loss into income (effective portion), net of tax	$ (97)	$ 54	$ (194)	$ (89)

Treasury Stock - Additional Inf

Treasury Stock - Additional Information (Detail)	27 Months Ended
	Mar. 31, 2018expansion	Feb. 21, 2018USD ($)	Nov. 04, 2015USD ($)
Equity [Abstract]
Stock repurchase program authorized amount (up to) | $		$ 300,000,000	$ 50,000,000
Number of expansions to stock repurchase program | expansion	2

Treasury Stock - Treasury Stock

Treasury Stock - Treasury Stock Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended		12 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Treasury Stock [Roll Forward]
Beginning balance (shares)	7,319,417	6,788,817	4,716,778	4,499,655	6,788,817	4,499,655	4,499,655
Ending balance (shares)	7,664,325	7,319,417	5,648,778	4,716,778	7,664,325	5,648,778	6,788,817	4,499,655
Beginning balance	$ 157,907	$ 143,357	$ 93,993	$ 88,756	$ 143,357	$ 88,756	$ 88,756
Ending balance	$ 167,919	$ 157,907	$ 116,592	$ 93,993	$ 167,919	$ 116,592	$ 143,357	$ 88,756
Average share price (usd per share)	$ 21.91	$ 21.57	$ 20.64	$ 19.93	$ 21.91	$ 20.64	$ 21.12	$ 19.73
Repurchases on open market
Treasury Stock [Roll Forward]
Shares repurchased (shares)	344,908		932,000		875,508	1,149,123
Shares repurchased	$ 10,012		$ 22,599		$ 24,562	$ 27,836
Average share price (usd per share)	$ 29.03		$ 24.25		$ 28.05	$ 24.22

Share-Based Compensation - Addi

Share-Based Compensation - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Compensation expense	$ 1	$ 0.8	$ 1.6	$ 1.5
Unrecognized compensation expense	$ 6.3		$ 6.3
Unrecognized compensation expense, weighted average remaining period			2 years 4 months 20 days

Accumulated Other Comprehensi61

Accumulated Other Comprehensive Loss (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018USD ($)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 318,026
Ending Balance	330,911
Foreign currency translation adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(3,636)
Other comprehensive (loss)/income before reclassifications	(795)
Amounts reclassified from accumulated other comprehensive loss	0
Net current period other comprehensive (loss)/income	(795)
Ending Balance	(4,431)
Net unrealized gain on derivatives, net of tax
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	987
Other comprehensive (loss)/income before reclassifications	1,513
Amounts reclassified from accumulated other comprehensive loss	(15)
Net current period other comprehensive (loss)/income	1,498
Ending Balance	2,485
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(2,649)
Other comprehensive (loss)/income before reclassifications	718
Amounts reclassified from accumulated other comprehensive loss	(15)
Net current period other comprehensive (loss)/income	703
Ending Balance	$ (1,946)

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Dec. 31, 2017	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Effective rate (as a percent)		22.20%
Discrete tax benefit		$ 0.6
Discrete tax benefit from stock compensation windfall		0.1
Discrete tax benefit related to re-measurement of deferred taxes		$ 0.5
Reduction in income tax expense due to Tax Cuts and Jobs Act of 2017	$ (9.2)

Earnings Per Share - Additional

Earnings Per Share - Additional Information (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share-based compensation awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (shares)	0	1,000	31,000	43,000

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net income	$ 21,895	$ 12,398	$ 35,541	$ 24,625
Weighted average number of shares outstanding- basic (shares)	36,879,774	39,125,571	37,154,750	39,349,674
Effect of dilutive securities:
Total effect of dilutive securities (shares)	148,223	84,648	160,197	105,254
Weighted average number of shares outstanding - diluted (shares)	37,027,997	39,210,219	37,314,947	39,454,928
Basic earnings per share (usd per share)	$ 0.59	$ 0.32	$ 0.96	$ 0.63
Diluted earnings per share (usd per share)	$ 0.59	$ 0.32	$ 0.95	$ 0.62
Restricted stock awards
Effect of dilutive securities:
Effect of dilutive securities (shares)	0	5,880	1,755	7,971
Restricted stock units
Effect of dilutive securities:
Effect of dilutive securities (shares)	56,188	39,988	64,100	57,169
Performance restricted stock units
Effect of dilutive securities:
Effect of dilutive securities (shares)	63,799	17,837	66,654	17,180
Stock options
Effect of dilutive securities:
Effect of dilutive securities (shares)	28,236	20,943	27,688	22,934

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Rent expense	$ 0.8	$ 0.9	$ 1.6	$ 1.7
Letter of Credit
Long-term Purchase Commitment [Line Items]
Outstanding amount of letters of credit	1.6		1.6		$ 1.6
Gas, Gypsum, Paper, and Other Raw Materials
Long-term Purchase Commitment [Line Items]
Non capital purchased under commitments	$ 23.3	$ 21.7	$ 43.5	$ 42.8

Commitments and Contingencies66

Commitments and Contingencies - Future Minimum Lease Payments Due Under Non-Cancelable Operating Leases and Purchase Commitments by Year (Detail) $ in Thousands	Jun. 30, 2018USD ($)
Future Minimum Lease Payments
July 1, 2018 - December 31, 2018	$ 360
2,019	1,658
2,020	48
2,021	0
2,022	0
2,023	0
Thereafter	0
Total	2,066
Purchase Commitments
July 1, 2018 - December 31, 2018	14,975
2,019	28,178
2,020	27,054
2,021	8,828
2,022	5,410
2,023	5,572
Thereafter	53,621
Total	$ 143,638

Segment Reporting - Additional

Segment Reporting - Additional Information (Detail) - geographic_area	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Number of geographical areas (geographic area)	2		2
Wallboard | Sales Revenue, Net | Product Concentration Risk
Segment Reporting Information [Line Items]
Percentage of revenues	97.40%	97.20%	97.10%	96.90%

Segment Reporting - Segment Rep

Segment Reporting - Segment Reporting (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net Sales:
Net Sales	$ 139,268	$ 120,630	$ 256,070	$ 241,245
Operating Income:
Operating income	30,560	21,620	51,322	43,307
Adjustments:
Interest expense	(2,694)	(3,062)	(5,414)	(5,978)
(Losses)/income from equity investment	(391)	345	(755)	175
Other expense, net	(87)	(135)	(227)	(779)
Income before provision for income taxes	27,388	18,768	44,926	36,725
Depreciation and Amortization
Total depreciation and amortization	10,805	12,474	21,386	23,760
Operating Segments | Wallboard
Net Sales:
Net Sales	135,667	117,194	248,638	233,670
Operating Income:
Operating income	31,122	21,819	52,152	43,411
Depreciation and Amortization
Total depreciation and amortization	10,411	12,177	20,717	23,199
Operating Segments | Other
Net Sales:
Net Sales	3,601	3,436	7,432	7,575
Operating Income:
Operating income	(562)	(199)	(830)	(104)
Depreciation and Amortization
Total depreciation and amortization	394	297	669	561
Adjustments
Adjustments:
Interest expense	(2,694)	(3,062)	(5,414)	(5,978)
(Losses)/income from equity investment	(391)	345	(755)	175
Other expense, net	$ (87)	$ (135)	$ (227)	$ (779)

Segment Reporting - Net Sales b

Segment Reporting - Net Sales by Geographic Region (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	$ 139,268	$ 120,630	$ 256,070	$ 241,245
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	132,513	113,665	242,488	224,051
Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	$ 6,755	$ 6,965	$ 13,582	$ 17,194

Segment Reporting - Assets by G

Segment Reporting - Assets by Geographic Region (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Fixed Assets	$ 292,451	$ 294,003
Total Assets	651,555	641,934
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Fixed Assets	289,099	290,324
Total Assets	633,576	622,836
Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Fixed Assets	3,352	3,679
Total Assets	$ 17,979	$ 19,098

Fair Value Disclosures (Details

Fair Value Disclosures (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	$ 506	$ 2,159
Derivative liability	40	613
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	506	2,159
Derivative liability	40	613
Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liability	0	0
Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	506	2,159
Derivative liability	40	613
Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liability	0	0
Interest rate swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	414	2,148
Derivative liability	0	0
Interest rate swap | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	414	2,148
Derivative liability	0	0
Interest rate swap | Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liability	0	0
Interest rate swap | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	414	2,148
Derivative liability	0	0
Interest rate swap | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liability	0	0
Commodity derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	92	11
Derivative liability	40	613
Commodity derivatives | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	92	11
Derivative liability	40	613
Commodity derivatives | Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liability	0	0
Commodity derivatives | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	92	11
Derivative liability	40	613
Commodity derivatives | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liability	$ 0	$ 0