Document and Entity Information - USD ($) $ in Billions	12 Months Ended
Document and Entity Information - USD ($) $ in Billions	Dec. 31, 2016	Feb. 07, 2017	Jun. 30, 2016
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2016
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	FY
Trading Symbol	TREX
Entity Registrant Name	TREX CO INC
Entity Central Index Key	0001069878
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		29,384,211
Entity Public Float			$ 1.3

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
Net sales	$ 479,616	$ 440,804	$ 391,660
Cost of sales	292,521	285,935	251,464
Gross profit	187,095	154,869	140,196
Selling, general and administrative expenses	83,140	77,463	72,370
Income from operations	103,955	77,406	67,826
Interest expense, net	1,125	619	878
Income before income taxes	102,830	76,787	66,948
Provision for income taxes	34,983	28,689	25,427
Net income	$ 67,847	$ 48,098	$ 41,521
Basic earnings per common share	$ 2.31	$ 1.53	$ 1.28
Basic weighted average common shares outstanding	29,394,559	31,350,542	32,319,649
Diluted earnings per common share	$ 2.29	$ 1.52	$ 1.27
Diluted weighted average common shares outstanding	29,612,669	31,682,509	32,751,074
Comprehensive income	$ 67,847	$ 48,098	$ 41,521

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current Assets:
Cash and cash equivalents	$ 18,664	$ 5,995
Accounts receivable, net	48,039	47,386
Inventories	28,546	23,104
Prepaid expenses and other assets	10,400	13,409
Deferred income taxes		9,136
Total current assets	105,649	99,030
Property, plant and equipment, net	103,286	100,924
Goodwill and other intangibles	10,523	10,526
Other assets	1,972	1,518
Total Assets	221,430	211,998
Current Liabilities:
Accounts payable	10,767	17,733
Accrued expenses	34,693	28,891
Accrued warranty	5,925	6,825
Line of Credit		7,000
Total current liabilities	51,385	60,449
Deferred income taxes	894	4,597
Non-current accrued warranty	31,767	26,698
Other long-term liabilities	3,223	3,791
Total Liabilities	87,269	95,535
Commitments and contingencies
Stockholders' Equity:
Preferred stock, $0.01 par value, 3,000,000 shares authorized; none issued and outstanding
Common stock, $0.01 par value, 80,000,000 shares authorized; 34,894,233 and 34,819,259 shares issued and 29,400,552 and 30,904,530 shares outstanding at December 31, 2016 and 2015, respectively	349	348
Additional paid-in capital	120,082	116,947
Retained earnings	187,242	119,395
Treasury stock, at cost, 5,493,681 and 3,914,729 shares at December 31, 2016 and 2015, respectively	(173,512)	(120,227)
Total Stockholders' Equity	134,161	116,463
Total Liabilities and Stockholders' Equity	$ 221,430	$ 211,998

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	3,000,000	3,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	80,000,000	80,000,000
Common stock, shares issued	34,894,233	34,819,259
Common stock, shares outstanding	29,400,552	30,904,530
Treasury stock, shares	5,493,681	3,914,729

Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings (Deficit) [Member]	Treasury Stock [Member]
Beginning Balance at Dec. 31, 2013	$ 106,616	$ 346	$ 101,494	$ 29,776	$ (25,000)
Beginning Balance, Shares at Dec. 31, 2013		33,475,614			1,122,510
Net income	41,521			41,521
Employee stock purchase and option plans	747	$ 1	746
Employee stock purchase and option plans, Shares		133,133
Shares withheld for taxes on share-based payment awards	(3,189)		(3,189)
Shares withheld for taxes on share-based payment awards, Shares		(36,610)
Stock-based compensation	4,807	$ 1	4,806
Stock-based compensation, Shares		105,905
Excess tax benefits from stock compensation	12,883		12,883
Shares repurchased under our publicly announced share repurchase programs	(50,000)				$ (50,000)
Shares repurchased under our publicly announced share repurchase programs, Shares					1,657,919
Shares repurchased under our publicly announced share repurchase programs, Shares		(1,657,919)
Ending Balance at Dec. 31, 2014	113,385	$ 348	116,740	71,297	$ (75,000)
Ending Balance, Shares at Dec. 31, 2014		32,020,123			2,780,429
Net income	48,098			48,098
Employee stock purchase and option plans	315	$ 1	314
Employee stock purchase and option plans, Shares		113,996
Shares withheld for taxes on share-based payment awards	(8,086)	$ (1)	(8,085)
Shares withheld for taxes on share-based payment awards, Shares		(115,453)
Stock-based compensation	4,861		4,861
Stock-based compensation, Shares		20,164
Excess tax benefits from stock compensation	3,117		3,117
Shares repurchased under our publicly announced share repurchase programs	(45,227)				$ (45,227)
Shares repurchased under our publicly announced share repurchase programs, Shares					1,134,300
Shares repurchased under our publicly announced share repurchase programs, Shares		(1,134,300)
Ending Balance at Dec. 31, 2015	116,463	$ 348	116,947	119,395	$ (120,227)
Ending Balance, Shares at Dec. 31, 2015		30,904,530			3,914,729
Net income	67,847			67,847
Employee stock purchase and option plans	280	$ 1	279
Employee stock purchase and option plans, Shares		79,175
Shares withheld for taxes on share-based payment awards	(1,933)	$ (1)	(1,932)
Shares withheld for taxes on share-based payment awards, Shares		(13,193)
Stock-based compensation	4,789	$ 1	4,788
Stock-based compensation, Shares		8,992
Shares repurchased under our publicly announced share repurchase programs	(53,285)				$ (53,285)
Shares repurchased under our publicly announced share repurchase programs, Shares					1,578,952
Shares repurchased under our publicly announced share repurchase programs, Shares		(1,578,952)
Ending Balance at Dec. 31, 2016	$ 134,161	$ 349	$ 120,082	$ 187,242	$ (173,512)
Ending Balance, Shares at Dec. 31, 2016		29,400,552			5,493,681

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Activities
Net income	$ 67,847	$ 48,098	$ 41,521
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	14,498	14,384	15,204
Deferred income taxes	5,433	1,024	3,574
Stock-based compensation	4,788	4,861	4,807
(Gain) Loss on disposal of property, plant and equipment	(185)	649	158
Excess tax benefits from stock compensation		(3,147)	(12,898)
Other non-cash adjustments	(284)	(271)	(245)
Changes in operating assets and liabilities:
Accounts receivable	(653)	(10,995)	867
Inventories	(5,442)	643	(1,319)
Prepaid expenses and other assets	(4,256)	905	(624)
Accounts payable	(6,966)	(2,317)	5,159
Accrued expenses and other liabilities	9,403	7,554	(7,535)
Income taxes receivable/payable	1,110	1,246	9,973
Net cash provided by operating activities	85,293	62,634	58,642
Investing Activities
Expenditures for property, plant and equipment	(14,551)	(23,333)	(12,974)
Proceeds from sales of property, plant and equipment	4,349	35	66
Purchase of acquired company, net of cash acquired		(31)	(44)
Notes receivable, net			79
Net cash used in investing activities	(10,202)	(23,329)	(12,873)
Financing Activities
Financing costs	(485)	(3)	(453)
Borrowings under line of credit	242,700	225,500	143,000
Principal payments under line of credit	(249,700)	(218,500)	(143,000)
Repurchases of common stock	(55,216)	(53,313)	(53,189)
Proceeds from employee stock purchase and option plans	279	315	747
Excess tax benefits from stock compensation		3,147	12,898
Net cash used in financing activities	(62,422)	(42,854)	(39,997)
Net increase (decrease) in cash and cash equivalents	12,669	(3,549)	5,772
Cash and cash equivalents at beginning of year	5,995	9,544	3,772
Cash and cash equivalents at end of year	18,664	5,995	9,544
Supplemental disclosures of cash flow information:
Cash paid for interest	852	625	520
Cash paid for income taxes, net	$ 28,626	$ 26,327	$ 11,919

Business and Organization

12 Months Ended

Dec. 31, 2016

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Business and Organization

1.	BUSINESS AND ORGANIZATION

Trex Company, Inc. (together with its subsidiary, the Company), a Delaware corporation, was incorporated on September 4, 1998. The Company manufactures and distributes wood/plastic composite products, as well as related accessories, primarily for residential and commercial decking and railing applications. A majority of its products are manufactured in a proprietary process that combines reclaimed wood fibers and scrap polyethylene. The Company operates in a single reportable segment.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2016

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2.	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Basis of Accounting

The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States and include the accounts of the Company and its wholly-owned subsidiary, Trex Wood-Polymer Espana, S.L. (TWPE). Intercompany accounts and transactions have been eliminated in consolidation.

TWPE was formed to hold the Company’s 35% equity interest in Denplax, S.A. (Denplax), a venture with a Spanish company responsible for public environmental programs in southern Spain and with an Italian equipment manufacturer. The venture was formed to recycle polyethylene at a facility in El Ejido, Spain. The Company’s investment in Denplax is accounted for using the equity method. During 2010, the Company determined that its investment in Denplax and a related note receivable were no longer recoverable and recorded a $2.4 million charge to earnings to fully reserve the equity investment and note. Both the equity investment and note remain fully reserved as of December 31, 2016.

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and the accompanying notes. Actual results could differ from those estimates.

Cash and Cash Equivalents

Cash equivalents consist of highly liquid investments purchased with original maturities of three months or less.

Concentrations and Credit Risk

The Company’s financial instruments that are exposed to concentrations of credit risk consist primarily of cash and cash equivalents and trade accounts receivable. The Company from time to time may have bank deposits in excess of insurance limits of the Federal Deposit Insurance Corporation. As of December 31, 2016, substantially all deposits are maintained in one financial institution. The Company has not experienced any losses in such accounts and believes it is not exposed to any significant credit risk related to its cash and cash equivalents.

The Company routinely assesses the financial strength of its customers and believes that its trade receivables credit risk exposure is limited. Trade receivables are carried at the original invoice amount less an estimate made for payment discounts and doubtful accounts. A valuation allowance is provided for known and anticipated credit losses and disputed amounts, as determined by management in the course of regularly evaluating individual customer receivables. This evaluation takes into consideration a customer’s financial condition and credit history, as well as current economic conditions. There was no valuation allowance recorded as of December 31, 2016 and 2015.

In the years ended December 31, 2016, 2015 and 2014, sales to certain customers accounted for 10% or more of the Company’s total net sales. For the year ended December 31, 2016, two customers of the Company represented approximately 39% of the Company’s net sales. For the year ended December 31, 2015, one customer of the Company represented approximately 27% of the Company’s net sales. For the year ended December 31, 2014, one customer of the Company represented approximately 24% of the Company’s net sales. At December 31, 2016, four customers represented 30%, 16%, 14%, and 13%, respectively, of the Company’s accounts receivable balance.

Approximately 33%, 35%, and 38% of the Company’s materials purchases for the years ended December 31, 2016, 2015 and 2014, respectively, were purchased from its four largest suppliers.

Inventories

Inventories are stated at the lower of cost (last-in, first-out, or LIFO, method) or market value. The Company periodically reviews its inventory for slow moving or obsolete items and writes down the related products to estimated realizable value. The Company’s reserves for estimated slow moving products or obsolescence are not material. At December 31, 2016, the excess of the replacement cost of inventory over the LIFO value of inventory was approximately $21.4 million. Due to the nature of the LIFO valuation methodology, liquidations of inventories will result in a portion of the Company’s cost of sales being based on historical rather than current year costs.

A majority of the Company’s products are made in a proprietary process that combines reclaimed wood fibers and scrap polyethylene. The Company grinds up scrap materials generated from its manufacturing process and inventories deemed no longer salable and reintroduces the reclaimed material into the manufacturing process as a substitute for raw materials. The reclaimed material is valued at the costs of the raw material components of the material.

Property, Plant and Equipment

Property, plant and equipment are stated at historical cost. The costs of additions and improvements are capitalized, while maintenance and repairs are expensed as incurred. Depreciation is provided using the straight-line method over the following estimated useful lives:


Buildings			40 years
Machinery and equipment			3-11 years
Furniture and equipment			10 years
Forklifts and tractors			5 years
Computer equipment and software			5 years

Leasehold improvements are amortized over the shorter of the lease term or the estimated useful life of the asset.

The Company reviews its long-lived assets, including property, plant and equipment, whenever events or changes in circumstances indicate that the carrying amount of the assets may not be fully recoverable. To determine the recoverability of its long-lived assets, the Company evaluates the probability that future estimated undiscounted net cash flows will be less than the carrying amount of the long-lived assets. If the estimated cash flows are less than the carrying amount of the long-lived assets, the assets are written down to their fair value. The Company’s estimates of anticipated cash flows and the remaining estimated useful lives of long-lived assets could be reduced in the future. As a result, the carrying amount of long-lived assets could be reduced in the future. Long-lived assets held for sale are stated at the lower of cost or fair value less cost to sell.

Fair Value Measurement

Assets and liabilities measured at fair value are measured at the amount that would be received for selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date and classified into one of the following fair value hierarchy:

•

Level 1 – Quoted prices for identical instruments in active markets.

•

Level 2 – Quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and model derived valuations in which all significant inputs and significant value drivers are observable in active markets.

•

Level 3 – Valuations derived from management’s best estimate of what market participants would use in pricing the asset or liability at the measurement date. Consideration is given to the risk inherent in the valuation technique and the risk inherent in the inputs to the model.

Contract Termination Costs

The Company leases 55,047 square feet of office and storage space in Dulles, Virginia, that it does not occupy, but has sublet all of the office space for the remainder of the term of its lease obligation, which ends June 30, 2019. The future sublease receipts are less than the remaining minimum lease payment obligations under the Company’s lease. Accordingly, the Company has recorded a liability for the present value of the shortfall.

Goodwill

Goodwill represents the excess of cost over net assets acquired resulting from the Company’s 1996 purchase of the Mobil Composite Products Division and the 2011 purchase of the assets of the Iron Deck Corporation. The Company evaluates the recoverability of goodwill in accordance with Accounting Standard Codification Topic 350, “Intangibles – Goodwill and Other,” annually or more frequently if an event occurs or circumstances change in the interim that would more likely than not reduce the fair value of the asset below its carrying amount. Goodwill is considered to be impaired when the net book value of the reporting unit exceeds its estimated fair value.

The Company first assesses qualitative factors to determine if it is more likely than not that the fair value of the reporting unit is less than its carrying amount to determine if it should proceed with the evaluation of goodwill for impairment. If the Company proceeds with the two-step impairment test, the Company first compares the fair value of the reporting unit to its carrying value. If the carrying value of a reporting unit exceeds its fair value, the goodwill of that reporting unit is potentially impaired and step two of the impairment analysis is performed. In step two of the analysis, an impairment loss is recorded equal to the excess of the carrying value of the reporting unit’s goodwill over its implied fair value should such a circumstance arise.

The Company measures fair value of the reporting unit based on a present value of future discounted cash flows and a market valuation approach. The discounted cash flows model indicates the fair value of the reporting unit based on the present value of the cash flows that the reporting unit is expected to generate in the future. Significant estimates in the discounted cash flows model include: the weighted average cost of capital; long-term rate of growth and profitability of the business; and working capital effects. The market valuation approach indicates the fair value of the business based on a comparison of the Company against certain market information. Significant estimates in the market approach model include identifying appropriate market multiples and assessing earnings before interest, income taxes, depreciation and amortization (EBITDA) in estimating the fair value of the reporting unit.

For the years ended December 31, 2016, 2015 and 2014, the Company completed its annual impairment test of goodwill and noted no impairment. The Company performs the annual impairment testing of its goodwill as of October 31 of each year. However, actual results could differ from the Company’s estimates and projections, which would affect the assessment of impairment. As of December 31, 2016, the Company had goodwill of $10.5 million that is reviewed annually for impairment.

Product Warranty

The Company warrants that its products will be free from material defects in workmanship and materials. This warranty generally extends for a period of 25 years for residential use and 10 years for commercial use. With respect to Trex Signature^® Railing, the warranty period is 25 years for both residential and commercial use. With respect to the Company’s Transcend^®, Enhance^®, Select^® and Universal Fascia product, the Company further warrants that the product will not fade in color more than a certain amount and will be resistant to permanent staining from food substances or mold, provided the stain is cleaned within seven days of appearance. This warranty extends for a period of 25 years for residential use and 10 years for commercial use. If there is a breach of such warranties, the Company has an obligation either to replace the defective product or refund the purchase price. The Company establishes warranty reserves to provide for estimated future expenses as a result of product defects that result in claims. Reserve estimates are based on management’s judgment, considering such factors as cost per claim, historical experience, anticipated rates of claims, and other available information. Management reviews and adjusts these estimates, if necessary, on a quarterly basis based on the differences between actual experience and historical estimates.

Treasury Stock

The Company records the repurchase of shares of its common stock at cost. These shares are considered treasury stock, which is a reduction to stockholders’ equity. Treasury stock is included in authorized and issued shares but excluded from outstanding shares.

Revenue Recognition

The Company recognizes revenue when title is transferred to customers, which is generally upon shipment of the product to the customer. The Company does not grant contractual product return rights to customers other than pursuant to its product warranty. The Company does not expect future product returns to be material and, consequently, does not maintain an allowance for product returns.

The Company records all shipping and handling fees in sales and records all of the related costs in cost of sales. The Company offers sales incentive programs to dealers and distributors, including rebates, pricing discounts, favorable payment terms and cooperative advertising, many of which result in cash consideration made to dealers and distributors. The Company accounts for consideration made pursuant to these programs in accordance with accounting guidance that governs consideration given by a vendor to a customer. With the exception of cooperative advertising, the Company classifies sales incentives as a reduction in revenue in “Net sales.” Sales incentives are recorded in the period in which they are earned by customers. The Company’s cooperative advertising program meets the requirements for exclusion from net sales and the costs are recorded as expenses in “Selling, general and administrative expenses” in the accompanying Consolidated Statements of Comprehensive Income. Cooperative advertising costs are expensed as incurred.

Stock-Based Compensation

The Company measures stock-based compensation at the grant date of the award based on the fair value. For stock options, stock appreciation rights and time-based restricted stock and time-based restricted stock units, stock-based compensation is recognized on a straight line basis over the vesting periods of the award. The Company recognizes forfeitures as they occur. For performance-based restricted stock and performance-based restricted stock units, expense is recognized ratably over the performance and vesting period of each tranche based on management’s judgment of the ultimate award that is probable to be paid out based on the achievement of predetermined performance measures. Stock-based compensation expense is included in “Selling, general and administrative expenses” in the accompanying Consolidated Statements of Comprehensive Income.

Income Taxes

The Company recognizes deferred tax assets and liabilities based on the difference between the financial statement basis and tax basis of assets and liabilities using enacted rates expected to be in effect during the year in which the differences reverse. The Company assesses the likelihood that its deferred tax assets will be realized. Deferred tax assets are reduced by a valuation allowance when, after considering all available positive and negative evidence, it is determined that it is more likely than not that some portion, or all, of the deferred tax asset will not be realized. As of December 31, 2016, the Company has a valuation allowance of $4.1 million against these deferred tax assets. The Company analyzes its position in subsequent reporting periods, considering all available positive and negative evidence, in determining the expected realization of its deferred tax assets.

Research and Development Costs

Research and development costs are expensed as incurred. For the years ended December 31, 2016, 2015 and 2014, research and development costs were $3.7 million, $1.5 million and $2.3 million, respectively, and have been included in “Selling, general and administrative expenses” in the accompanying Consolidated Statements of Comprehensive Income.

Advertising Costs

The Company expenses its branding and advertising communication costs as incurred. Significant production costs are deferred and recognized as expense in the period that the related advertisement is first used. At December 31, 2016 and December 31, 2015, $2.4 million and $0.8 million, respectively, were included in prepaid expenses for production costs.

For the years ended December 31, 2016, 2015 and 2014, branding expenses, including advertising expenses as described above, were $24.8 million, $23.4 million and $20.8 million, respectively.

Fair Value of Financial Instruments

The Company considers the recorded value of its financial assets and liabilities, consisting primarily of cash and cash equivalents, accounts receivable, accounts payable, accrued expenses and other current liabilities to approximate the fair value of the respective assets and liabilities at December 31, 2016 and 2015.

Recently Adopted Accounting Standards

In November 2015, the Financial Accounting Standards Board issued Accounting Standards Update (ASU) No. 2015-17, “Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes.” The standard requires that all deferred tax assets and liabilities for a particular tax-paying component of an entity and within a particular tax jurisdiction, along with any valuation allowance, be offset and classified as a single noncurrent deferred tax asset or liability regardless of their nature or expected timing of reversal or recovery. The standard may be applied either prospectively, for all deferred tax assets and liabilities, or retrospectively. The standard is effective for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years. Early adoption is permitted. The Company elected to early adopt the standard in the quarterly period ended December 31, 2016. The Company applied the standard prospectively in the fourth quarter of fiscal 2016 and, accordingly, prior periods were not adjusted. Adoption of the standard will not impact the Company’s financial debt covenants or restrictions, and deferred tax assets and deferred tax liabilities are no longer reported in current assets or current liabilities.

In March 2016, the FASB issued ASU No. 2016-09, “Compensation – Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting.” The standard amends certain aspects of accounting for employee share-based payment transactions, including the accounting for income taxes related to those transactions and forfeitures. The standard requires recognizing excess tax benefits and deficiencies on share-based awards in the tax provision, instead of in equity. Also, the standard requires these amounts to be classified as an operating activity, and shares withheld to satisfy employee taxes to be classified as a financing activity in the statement of cash flows, rather than as currently classified as financing and operating activities, respectively. The standard is effective for annual reporting periods beginning after December 15, 2016 and interim periods within that reporting period, with early adoption permitted. The Company elected to early adopt the standard in fiscal year 2016. The impact of the early adoption resulted in the following:

•

The Company recorded a tax benefit of $1.7 million within income tax expense related to the excess tax benefits of the settlement or vesting of time-based restricted stock or time-based restricted stock units and performance-based restricted stock or performance-based restricted stock units. The Company applied this guidance prospectively as of January 1, 2016 and, accordingly, data for the prior years ended December 31, 2015 and 2014 were not adjusted. Prior to adoption this amount would have been recorded as an increase in additional paid-in capital. Going forward, this change could create volatility in the Company’s effective tax rate.

•

The Company elected to change its policy on accounting for forfeitures and recognize forfeitures as they occur. The Company applied this guidance on a modified retrospective transition method. The Company determined that the cumulative effect of applying the guidance under the modified retrospective transition method was not material to its Consolidated Financial Statements

•

Excess tax benefits are now reported as an operating activity in the Company’s Consolidated Statements of Cash Flows, rather than as a financing activity as was previously reported. As the Company applied this guidance prospectively as of January 1, 2016, excess tax benefits for the years ended December 31, 2015 and December 31, 2014 were not adjusted and continue to be reported in financing activities in the Consolidated Statements of Cash Flows.

•

The standard requires the presentation of employee taxes as a financing activity in the Consolidated Statements of Cash Flows. This provision did not impact the Company’s Consolidated Financial Statements as the Company currently presents employee taxes as a financing activity in its Consolidated Statements of Cash Flows.

The Company excluded the excess tax benefits from the assumed proceeds available to repurchase shares in the computation of diluted earnings per share for 2016, which did not materially increase the diluted weighted average common shares outstanding. Data reported in Note 14, “Interim Financial Data (Unaudited),“for net income, diluted net income per share and diluted weighted average common shares outstanding for the each quarterly period in the fiscal year ended December 31, 2016, reflect adoption of the new standard.

New Accounting Standards Not Yet Adopted

In May 2014, the FASB issued ASU No. 2014-09, “Revenue from Contracts with Customers,” and issued subsequent amendments to the initial guidance in August 2015 within ASU 2015-14, in March 2016 within ASU 2016-08, in April 2016 within ASU 2016-10, and in May 2016 within ASU 2016-12 (collectively, the new standard). The new standard provides a single, comprehensive model for revenue arising from contracts with customers and supersedes most current revenue recognition guidance. The new standard requires an entity to recognize revenue at an amount that reflects the consideration to which the company expects to be entitled in exchange for transferring goods or services to a customer. The Company intends to adopt the new standard in the first quarterly period of fiscal 2018. Currently, the Company intends to use the retrospective application to each reporting period presented, with the option to elect certain practical expedients as defined in the new standard. The Company does not believe adoption of the new standard will have a material impact on its Consolidated Statements of Comprehensive Income, but expects expanded financial statement footnote disclosure. The Company is continuing to evaluate the impacts of the pending adoption. As such, the Company’s preliminary assessments are subject to change.

In February 2016, the FASB issued ASU No. 2016-02, “Leases (Topic 842).” The standard requires lessees to recognize leases on the balance sheet as a right-of-use asset and a lease liability, other than leases that meet the definition of a short-term lease. The liability will be equal to the present value of the lease payments. The asset will be based on the liability, subject to adjustment. For income statement purposes, the leases will continue to be classified as either operating or finance. Operating leases will result in straight-line expense (similar to current operating leases) and finance leases will result in a front-loaded expense pattern (similar to current capital leases). The standard is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted. The standard must be adopted using the modified retrospective transition method and provides for the option to elect a package of practical expedients upon adoption. The Company intends to adopt the standard in the first quarterly period of fiscal 2019, and is currently assessing the impact of adoption of the standard on its consolidated financial statements and related note disclosures. The Company has not made any decision on the option to elect adoption of the practical expedients.

In August 2016, the FASB issued ASU No. 2016-15, “Statement of Cash flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments.” The guidance is intended to reduce diversity in practice across all industries in how certain transactions are classified in the statement of cash flows. The standard is effective for financial statements issued for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted. The guidance requires application using a retrospective translation method. The Company is assessing the impact of adoption of the new standard on its consolidated financial statements and related note disclosures.

Reclassifications

Certain prior year amounts have been reclassified to conform to the current year presentation.

Inventories

12 Months Ended

Dec. 31, 2016

Inventory Disclosure [Abstract]

Inventories

3.	INVENTORIES

Inventories (at LIFO value) consist of the following as of December 31 (in thousands):


	2016			2015
Finished goods	$	29,686		$	24,961
Raw materials		20,231			21,384

Total FIFO (first-in, first out) inventories		49,917			46,345
Reserve to adjust inventories to LIFO value		(21,371	)		(23,241	)

Total LIFO inventories	$	28,546		$	23,104

Inventory is stated at the lower of LIFO cost or net realizable value. The Company periodically reviews its inventory for slow moving or obsolete items and writes down the related products to estimated net realizable value.

Under the LIFO method, reductions in inventory cause a portion of the Company’s cost of sales to be based on historical costs rather than current year costs. There was no inventory reduction during 2016. There was an inventory reduction in 2015. However, the impact on the Company’s cost of sales was not material due the fact that the historical costs expensed during 2015 closely approximated the current year costs.

Prepaid Expenses and Other Assets

12 Months Ended

Dec. 31, 2016

Text Block [Abstract]

Prepaid Expenses and Other Assets

4.	PREPAID EXPENSES AND OTHER ASSETS

Prepaid expenses and other assets consist of the following as of December 31 (in thousands):


	2016		2015
Prepaid expenses	$	6,209	$	1,897
Income tax receivable		4,024		5,134
Assets held for sale		—		6,154
Other		167		224

Total prepaid expenses and other assets	$	10,400	$	13,409

At December 31, 2015, assets held for sale consisted of assets at the idle Olive Branch, Mississippi facility (Olive Branch assets) consisting of land and buildings and measured at the lower of their carrying amount or fair value less cost to sell. Fair value was determined using the Level 3 fair value hierarchy classification and was based on management’s best estimate of market participants’ pricing of the assets, including input from broker and industry specialists, and considered the condition of the assets.

Property, Plant and Equipment

12 Months Ended

Dec. 31, 2016

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

5.	PROPERTY, PLANT AND EQUIPMENT

Property, plant and equipment consist of the following as of December 31 (in thousands):


	2016			2015
Building and improvements	$	47,859		$	47,209
Machinery and equipment		223,450			210,880
Furniture and fixtures		2,710			2,221
Forklifts and tractors		10,167			7,607
Computer equipment		10,481			9,575
Construction in process		4,172			11,032
Land		11,417			8,532

Total property, plant and equipment		310,256			297,056
Accumulated depreciation		(206,970	)		(196,132	)

Total property, plant and equipment, net	$	103,286		$	100,924

The Company had construction in process as of December 31, 2016 of approximately $4.2 million. The Company expects that the construction in process will be completed and put into service in the year ending December 31, 2017.

Depreciation expense for the years ended December 31, 2016, 2015, and 2014 totaled $14.2 million, $14.3 million and $14.8 million, respectively.

During December 2015, the Company reclassified the Olive Branch assets from “Property, plant and equipment, net,” to assets held for sale in “Prepaid expenses and other assets” in the Consolidated Balance Sheet. The transfer to a held for sale category was due to the signing of letters of intent to sell certain of the Olive Branch assets. Upon transfer during December 2015, the Company measured the Olive Branch assets at the lower of their carrying amount or fair value less cost to sell, and recognized a loss of $0.5 million, which is reported in “Selling, general and administrative expenses” in the Consolidated Statements of Comprehensive Income for the year ended December 31, 2015. In January 2016, the Company sold a portion of the Olive Branch facility that contained the buildings for $4.2 million and recognized a $0.1 million gain on sale, which is reported in “Selling, general and administrative expenses” in the Consolidated Statements of Comprehensive Income. As of December 31, 2016, the Company continues to own approximately 62 acres of undeveloped land that is reported in “Property, plant and equipment, net” in the Consolidated Balance Sheet.

Accrued Expenses

12 Months Ended

Dec. 31, 2016

Payables and Accruals [Abstract]

Accrued Expenses

6.	ACCRUED EXPENSES

Accrued expenses consist of the following (in thousands):


	2016		2015
Sales and marketing costs	$	16,707	$	11,928
Compensation and benefits		13,298		11,217
Manufacturing costs		1,799		1,732
Rent obligations		632		664
Other		2,257		3,350

Total accrued expenses	$	34,693	$	28,891

Debt

12 Months Ended

Dec. 31, 2016

Debt Disclosure [Abstract]

Debt

DEBT

The Company’s debt consists of a revolving credit facility. At December 31, 2016, the Company had no outstanding indebtedness. Available borrowing capacity at December 31, 2016, was $200 million. At December 31, 2015, the Company had $7.0 million of outstanding indebtedness, and the interest rate on the revolving credit facility was 1.39%.

Revolving Credit Facility

Indebtedness after December 31, 2015. On January 12, 2016, the Company entered into a Third Amended and Restated Credit Agreement and also the First Amendment to the Third Amended and Restated Credit Agreement (together, the Third Amended Credit Agreement) with Bank of America, N.A. (BOA) as Lender, Administrative Agent, Swing Line Lender and Letter of Credit Issuer; and certain other lenders including Citibank, N.A., Capital One, N.A., and SunTrust Bank (collectively, Lenders) arranged by Bank of America Merrill Lynch as Sole Lead Arranger and Sole Bookrunner. The Third Amended Credit Agreement amended and restated the Second Amended Credit Agreement.

Under the Third Amended Credit Agreement, the Lenders agree to provide the Company with one or more revolving loans in a collective maximum principal amount of $250 million from January 1 through June 30 of each year and a maximum principal amount of $200 million from July 1 through December 31 of each year throughout the term, which ends January 12, 2021. Included within the revolving loan limit are sublimits for a letter of credit facility in an amount not to exceed $15 million and swing line loans in an aggregate principal amount at any time outstanding not to exceed $5 million. The revolving loans, the letter of credit facility and the swing line loans are for the purpose of funding working capital needs and supporting general business operations. Additionally, within the Revolving Loan Limit, the Company could borrow, repay, and reborrow, at any time or from time to time while the Third Amended Credit Agreement is in effect.

The Company has the option to select interest rates for each loan request at the Base Rate or Eurodollar Rate. Base rate loans under the revolving loans and the swing line loans accrue interest at the Base Rate plus the Applicable Rate. Eurodollar Rate Loans for the revolving loans and swing line loans accrue interest at the Adjusted London InterBank Offered Rate plus the Applicable Rate. The Base Rate for any day is a fluctuating rate per annum equal to the highest of (a) the Federal Funds Rate plus 0.50%, (b) the rate of interest in effect for such day as publicly announced from time to time by BOA as its prime rate, and (c) the Eurodollar Rate plus 1.0%. Repayment of all then outstanding principal, interest, fees and costs is due on January 12, 2021.

The Company shall reimburse BOA for all amounts payable, including interest, under a letter of credit at the earlier of (i) the date set forth in the application, or (ii) one business day after the payment under such letter of credit by BOA.

The Third Amended Credit Agreement is secured by property with respect to which liens in favor of the Administrative Agent, for the benefit of itself and the other holders of the obligations, are purported to be granted pursuant to and in accordance with the terms of the collateral documents as referenced in the Third Amended Credit Agreement.

Indebtedness through December 31, 2015. On November 20, 2014, the Company entered into a Second Amended and Restated Credit Agreement (Second Amended Credit Agreement) with Branch Banking and Trust Company (BB&T), as a Lender, Administrative Agent, Swing Line Lender and Letter of Credit Issuer; Citibank, N.A. and Bank of America, N.A., each as a Lender, and BB&T Capital Markets, as Lead Arranger. The Second Amended Credit Agreement amended and restated the Amended and Restated Credit Agreement (Prior Credit Agreement) dated as of January 6, 2012 by and among the Company, as borrower; BB&T as Lender, Administrative Agent, Swing Line Lender, Letter of Credit Issuer and a Collateral Agent; Wells Fargo Capital Finance, LLC, as a Lender and a Collateral Agent; and BB&T Capital Markets, as Lead Arranger, and as further amended. Under the Prior Credit Agreement, BB&T and Wells Fargo provided the Company with one or more revolving loans in a collective maximum principal amount of $100 million. The Second Amended Credit Agreement terminated the Revolver Notes and Swing Advance Notes under the Prior Credit Agreement. No additional fees were due or owing as a result of the termination of the aforementioned agreements.

The Second Amended Credit Agreement provided the Company with one or more revolving loans in a collective maximum principal amount of $150 million from January 1 through June 30 of each year and a maximum principal amount of $100 million from July 1 through December 31 of each year (Revolving Loan Limit) throughout the term of November 20, 2019.

Included within the Revolving Loan Limit were sublimits for a letter of credit facility in an amount not to exceed $15 million and swing advances in an aggregate principal amount at any time outstanding not to exceed $5 million. The Revolver Loans, the Letter of Credit Facility and the Swing Advance loans were for the purpose of raising working capital and supporting general business operations. The Company was not obligated to borrow any amount under the Revolving Loan Limit. Additionally, within the Revolving Loan Limit, the Company could borrow, repay, and reborrow, at any time or from time to time while the Second Amended Credit Agreement is in effect.

Base Rate Advances (as defined in the Second Amended Credit Agreement) under the Revolver Loans and the Swing Advances accrued interest at the Base Rate plus the Applicable Margin (as defined in the Second Amended Credit Agreement) and Euro-dollar Advances for the Revolver Loans and Swing Advances accrued interest at the Adjusted London InterBank Offered Rate plus the Applicable Margin (as defined in the Second Amended Credit Agreement).

The Company was required to reimburse BB&T for all amounts payable, including interest, under a Letter of Credit at the earlier of (i) the date set forth in the application, or (ii) one business day after the payment under such Letter of Credit by BB&T.

The Second Amended Credit Agreement was secured by interest in real property owned by us and certain collateral (as described in the Second Amended and Restated Security Agreement and Intellectual Property Security Agreement).

Compliance with Debt Covenants and Restrictions. The Company’s ability to make scheduled principal and interest payments, borrow and repay amounts under any outstanding revolving credit facility and continue to comply with any loan covenants depends primarily on its ability to generate sufficient cash flows from operations. To remain in compliance with financial covenants, the Company is required to maintain specified financial ratios based on levels of debt, fixed charges, and earnings (excluding extraordinary gains and extraordinary non-cash losses) before interest, taxes, depreciation and amortization, all of which are subject to the risks of the business, some of which are discussed in this report under “Risk Factors.” The material financial covenants and restrictions do not permit the Company’s fixed charge coverage ratio to be less than 1.5 to 1.0 and do not permit the Company’s consolidated debt to consolidated EBITDA ratio to exceed 3.0 to 1.0, measured as of the end of each fiscal quarter (and in the case of Consolidated EBITDA, for the four-quarter period ending on such date). The Company was in compliance with all covenants contained in the Third Amended Credit Agreement at December 31, 2016. Failure to comply with the financial covenants could be considered a default of repayment obligations and, among other remedies, could accelerate payment of any amounts outstanding.

Stockholders' Equity

12 Months Ended

Dec. 31, 2016

Equity [Abstract]

Stockholders' Equity

8.	STOCKHOLDERS’ EQUITY

Earnings Per Share

The following table sets forth the computation of basic and diluted earnings per share (in thousands, except share and per share data):


	Year Ended December 31,
	2016		2015		2014
Numerator:
Net income	$	67,847	$	48,098	$	41,521

Denominator:
Basic weighted average shares outstanding		29,394,559		31,350,542		32,319,649
Effect of dilutive securities:
SARS and options		125,119		197,299		262,730
Restricted stock		92,991		134,668		168,695

Diluted weighted average shares outstanding		29,612,669		31,682,509		32,751,074

Basic earnings per share	$	2.31	$	1.53	$	1.28

Diluted earnings per share	$	2.29	$	1.52	$	1.27

Diluted earnings per share is computed using the weighted average number of shares determined for the basic earnings per share computation plus the dilutive effect of common stock equivalents using the treasury stock method. The computation of diluted earnings per share excludes the following potentially dilutive securities because the effect would be anti-dilutive:


	Year Ended December 31,
	2016		2015		2014
Restricted stock and stock options		12		501		2,633
Stock appreciation rights		4,631		5,828		1,969

Stock Repurchase Programs

On February 19, 2014, the Board of Directors authorized a common stock repurchase program of up to $50 million shares of the Company’s outstanding common stock (February 2014 Stock Repurchase Program). This authorization had no expiration date. During 2014, the Company repurchased 1,657,919 shares for $50.0 million, which completed the authorization under the February 2014 Stock Repurchase Program.

On October 23, 2014, the Board of Directors authorized a common stock repurchase program of up to 2.0 million shares of the Company’s outstanding common stock (October 2014 Stock Repurchase Program). This authorization had no expiration date. During 2015, the Company repurchased 1,134,300 shares for $45.2 million under the October 2014 Stock Repurchase Program. On October 22, 2015, the Board of Directors terminated the October 2014 Stock Repurchase Program and adopted a new stock repurchase program of up to 3.15 million shares of the Company’s outstanding common stock (October 2015 Stock Repurchase Program). This authorization terminated on December 31, 2016. During 2016, the Company repurchased 1,578,952 shares for $53.3 million under the October 2015 Stock Repurchase Program.

On February 16, 2017, the Board of Directors authorized a common stock repurchase program of up to 2.961 million shares of the Company’s outstanding common stock (February 2017 Stock Repurchase Program). As of the date of this report, the Company has made no repurchases under the February 2017 Stock Repurchase Program.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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-Subparagraph (SX 210.5-02(31))
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 4
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
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-Name Accounting Standards Codification
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Reference 12: http://www.xbrl.org/2003/role/presentationRef
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Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Preferred Stock
-URI http://asc.fasb.org/extlink&oid=6521494

Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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+ Details

Stock-Based Compensation

12 Months Ended

Dec. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation

9.	STOCK-BASED COMPENSATION

On April 30, 2014, the Company’s stockholders approved the Trex Company, Inc. 2014 Stock Incentive Plan (Plan), which was previously approved by the Board of Directors on February 19, 2014. The Plan amended and restated in its entirety the Trex Company, Inc. 2005 Stock Incentive Plan, as previously disclosed. The Plan is administered by the Compensation Committee of the Company’s Board of Directors. Stock-based compensation is granted to officers, directors and certain key employees in accordance with the provisions of the Plan. The Plan provides for grants of stock options, restricted stock, restricted stock units, stock appreciation rights (SARs), and unrestricted stock. The total aggregate number of shares of the Company’s common stock that may be issued under the Plan is 6,420,000.

In 2014, the Company began granting performance-based restricted stock in addition to the time-based restricted stock it previously granted. The performance-based restricted shares have a three-year vesting period, vesting one-third each year based on target earnings before interest, taxes, depreciation and amortization for 1 year, cumulative 2 years and cumulative 3 years, respectively. The number of shares that vest, with respect to each vesting, will be between 0% and 200% of the target number of shares.

In 2015, the Company began issuing restricted stock units in lieu of restricted stock. Accordingly, time-based restricted stock units replaced time-based restricted stock and performance-based restricted stock units replaced performance-based restricted stock. The vesting terms of the restricted stock units are identical to the vesting provisions of the restricted stock.

The Company recognizes stock-based compensation expense ratably over the period from grant date to the earlier of (1) the vesting date of the award, or (2) the date the grantee is eligible to retire without forfeiting the award. For performance-based restricted stock and performance-based restricted stock units, expense is recognized ratably over the performance and vesting period of each tranche based on management’s judgment of the ultimate award that is probable to be paid out based on the achievement of the predetermined performance measures. For the employee stock purchase plan, compensation expense is recognized related to the discount on purchases. The following table summarizes the Company’s stock-based compensation expense for the years ended December 31, 2016, 2015 and 2014 (in thousands):


	Year Ended December 31,
	2016		2015		2014
Time-based restricted stock and time-based restricted stock units	$	2,281	$	2,704	$	2,974
Performance-based restricted stock and performance-based restricted stock units		2,210		1,562		727
Stock appreciation rights		184		525		1,035
Employee stock purchase plan		113		70		71

Total stock-based compensation	$	4,788	$	4,861	$	4,807

Stock-based compensation expense is included in “Selling, general and administrative expenses” in the accompanying Consolidated Statements of Comprehensive Income.

Time-Based Restricted Stock and Time-Based Restricted Stock Units

The fair value of time-based restricted stock and time-based restricted stock units is determined based on the closing price of the Company’s shares on the grant date. Time-based restricted stock and time-based restricted stock units vest based on the terms of the awards. Unvested time-based restricted stock and unvested time-based restricted stock units are generally forfeitable upon the resignation of employment or termination of employment with cause. The total fair value of vested time-based restricted shares and vested time-based restricted stock units for the years ended December 31, 2016, 2015 and 2014 was $1.7 million, $9.8 million, and $3.9 million, respectively. At December 31, 2016, there was $1.5 million of total compensation expense related to unvested time-based restricted stock and unvested time-based restricted stock units remaining to be recognized over a weighted-average period of approximately 1.6 years.

Time-based restricted stock activity under the Plan and all predecessor stock incentive plans is as follows:


	Time-based Restricted Stock			Weighted-Average Grant Price Per Share
Nonvested at December 31, 2013		382,974		$	13.78
Granted		66,511		$	32.70
Vested		(116,641	)	$	33.73
Forfeited		(3,282	)	$	16.61

Nonvested at December 31, 2014		329,562		$	18.89
Granted		57,598		$	43.81
Vested		(230,704	)	$	42.37
Forfeited		(48,549	)	$	20.20

Nonvested at December 31, 2015		107,907		$	29.43
Granted		57,874		$	37.64
Vested		(43,848	)	$	42.34
Forfeited		(133	)	$	43.89

Nonvested at December 31, 2016		121,800		$	31.59

Performance-based Restricted Stock and Performance-Based Restricted Stock Units

The fair value of performance-based restricted stock and performance-based restricted stock units is determined based on the closing price of the Company’s shares on the grant date. Unvested performance-based restricted stock and unvested performance-based restricted stock units are generally forfeitable upon the resignation of employment or termination of employment with cause. The performance-based restricted shares and performance-based restricted stock units have a three-year vesting period, vesting one-third each year based on target earnings before interest, taxes, depreciation and amortization (EBITDA) for 1 year, cumulative 2 years and cumulative 3 years, respectively. The number of shares that will vest, with respect to each vesting, will be between 0% and 200% of the target number of shares. At December 31, 2016 and 2015, there was $1.2 million and $0.6 million, respectively, of total compensation expense related to unvested performance-based restricted stock and unvested performance-based restricted stock units remaining to be recognized over a weighted-average period of approximately 2.0 years.

Performance-based restricted stock activity under the Plan is as follows:


	Performance-based Restricted Stock and Performance-based Restricted Stock Units			Weighted-Average Grant Price Per Share
Nonvested at December 31, 2014		42,676		$	33.72
Granted		34,638		$	43.89
Vested		(35,679	)	$	41.91
Forfeited		(12,538	)	$	38.12

Nonvested at December 31, 2015		29,097		$	39.38
Granted		44,925		$	35.83
Vested		(14,949	)	$	35.71
Forfeited		(657	)	$	33.72

Nonvested at December 31, 2016		58,416		$	36.63

Stock Appreciation Rights

SARs are granted with a grant price equal to the closing market price of the Company’s common stock on the date of grant. These awards expire ten years after the date of grant and vest based on the terms of the individual awards. The SARs are generally forfeitable upon the resignation of employment or termination of employment with cause. The Company recognizes compensation cost on a straight-line basis over the vesting period for the award.

As of December 31, 2016, there was no unrecognized compensation cost related to SARs. The fair value of each SAR is estimated on the date of grant using a Black-Scholes option-pricing model. There were no SARs issued in the year ended December 31, 2016. For SARs issued in the years ended December 31, 2015 and 2014, respectively, the assumptions shown in the following table were used:


	December 31,
	2015			2014
Dividend yield		0	%		0	%
Average risk-free interest rate		1.6	%		1.7	%
Expected term (years)		5			5
Expected volatility		42.9	%		52.6	%

Dividend Yield. The Company has never paid cash dividends on its common stock.

Average Risk-Free Interest Rate. The Company uses the U.S. Treasury rate having a term that most closely resembles the expected term of the option.

Expected Term. The expected term is the period of time that the SARs granted are expected to remain unexercised. SARs granted during the year ended December 31, 2015 had a maximum term of ten years. The Company used historical exercise behavior with further consideration given to the class of employees to whom the equity awards were granted to estimate the expected term of the SAR.

Expected Volatility. Volatility is a measure of the amount by which a financial variable such as a share price has fluctuated (historical volatility) or is expected to fluctuate (expected volatility) during a period. The Company has used the historical volatility over the average expected term of the options granted as the expected volatility.

The Company recognizes forfeitures as they occur.

The weighted-average grant date fair value of SARs granted during the years ended December 31, 2015 and 2014 was $16.26, and $17.78, respectively.

SAR activity under the Plan and all predecessor stock incentive plans is as follows:


	SARs			Weighted-Average Grant Price Per Share		Weighted- Average Remaining Contractual Life (Years)		Aggregate Intrinsic Value as of December 31, 2016
Outstanding at December 31, 2013		739,194		$	12.93
Granted		3,866		$	37.88
Exercised		(218,826	)	$	10.96
Canceled		(8,404	)	$	4.74

Outstanding at December 31, 2014		515,830		$	13.98
Granted		15,585		$	41.19
Exercised		(263,626	)	$	13.86
Canceled		(5,712	)	$	21.94

Outstanding at December 31, 2015		262,077		$	13.13
Granted		—		$	—
Exercised		(124,352	)	$	11.09
Canceled		—		$	—

Outstanding at December 31, 2016		137,725		$	19.57		5.6	$	6,174,886
Vested at December 31, 2016		127,469		$	17.83		5.4	$	5,936,639
Exercisable at December 31, 2016		127,469		$	17.83		5.4	$	5,936,639

Employee Stock Purchase Plan

The Company has an employee stock purchase plan (ESPP) that permits eligible employees to purchase shares of common stock of the Company at a purchase price which is the lesser of 85% of the market price on either the first day of the calendar quarter or the last day of the calendar quarter. Eligible employees may elect to participate in the plan by authorizing payroll deductions of up to 15% of gross compensation for each payroll period. On the last day of each quarter, each participant’s contribution account is used to purchase the maximum number of whole shares of common stock determined by dividing the contribution account balance by the purchase price. The aggregate number of shares of common stock that may be purchased under the plan is 600,000. Through December 31, 2016, employees had purchased approximately 422,687 shares under the plan.

Stock Options

Stock options are granted with an exercise price equal to the closing market price of the Company’s common stock on the date of grant. These awards expire ten years after the date of grant and vest based on the terms of the individual awards. The options are generally forfeitable upon termination of a holder’s service as an employee or director, unless the individual’s service is terminated due to retirement, death or permanent disability. The fair value of each stock option award is estimated on the date of grant using a Black-Scholes option-pricing model. The Company recognizes compensation cost on a straight-line basis over the vesting period for the award. All outstanding options were exercised during fiscal 2015 and there were no stock options outstanding at December 31, 2015 and 2016.

Stock option activity under the Plan and all predecessor stock incentive plans is as follows:


	Options			Weighted-Average Exercise Price Per Share
Outstanding at December 31, 2013		42,288		$	20.05
Granted		—		$	—
Exercised		(27,942	)	$	35.73
Canceled		(1,188	)	$	17.92

Outstanding at December 31, 2014		13,158		$	23.36
Granted		—		$	—
Exercised		(13,158	)	$	50.37
Canceled		—		$	—

Outstanding at December 31, 2015		—		$	—

- 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, 2016

Leases [Abstract]

Leases

10.

LEASES

The Company leases office space, storage warehouses and certain office and plant equipment under various operating leases. Minimum annual payments under these non-cancelable leases as of December 31, 2016 were as follows (in thousands):


Year Ending December 31,
2017	$	9,606
2018		9,271
2019		8,205
2020		6,477
2021		6,170
Thereafter		18,659

Total minimum lease payments	$	58,388

For the years ended December 31, 2016, 2015 and 2014, the Company recognized rental expenses of approximately $9.9 million, $7.7 million and $7.5 million, respectively.

For information related to the Company’s reconsidered corporate headquarters lease agreement, see Note 13.

Income Taxes

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Income Taxes

12.

INCOME TAXES

Income tax provision (benefit) for the years ended December 31, 2016, 2015 and 2014 consists of the following (in thousands):


	Year Ended December 31,
	2016		2015		2014
Current income tax provision:
Federal	$	26,752	$	25,105	$	18,722
State		2,798		2,560		3,131

		29,550		27,665		21,853

Deferred income tax provision:
Federal		5,217		987		3,118
State		216		37		456

		5,433		1,024		3,574

Total income tax provision	$	34,983	$	28,689	$	25,427

The income tax provision differs from the amount of income tax determined by applying the U.S. Federal statutory rate to income before taxes as a result of the following (in thousands):


	Year Ended December 31,
	2016			2015			2014
U.S. Federal statutory taxes	$	35,990		$	26,876		$	23,432
State and local taxes, net of U.S. Federal benefit		3,747			2,806			2,856
Permanent items		396			1,308			249
Excess tax benefits from vesting or settlement of stock compensation awards		(1,749	)		—			—
Domestic production activities deduction		(2,740	)		(2,262	)		(1,117	)
Federal credits		(488	)		(328	)		(214	)
Other		(173	)		289			221

Total income tax provision	$	34,983		$	28,689		$	25,427

Deferred tax assets and liabilities as of December 31, 2016 and 2015 consist of the following (in thousands):


	As of December 31,
	2016			2015
Deferred tax assets:
Net operating losses	$	93		$	138
Warranty reserve		14,510			12,904
Stock-based compensation		2,186			1,554
Accruals not currently deductible and other		2,261			6,195
Inventories		5,785			4,406
State tax credit carryforwards		4,020			4,350

Gross deferred tax assets, before valuation allowance		28,855			29,547
Valuation allowance		(4,061	)		(4,582	)

Gross deferred tax assets, after valuation allowance		24,794			24,965

Deferred tax liabilities:
Depreciation and other		(25,688	)		(20,426	)

Gross deferred tax liabilities		(25,688	)		(20,426	)

Net deferred tax (liability) asset	$	(894	)	$	4,539

The Company recognizes deferred tax assets and liabilities based on the difference between the financial statement basis and tax basis of assets and liabilities using enacted rates expected to be in effect during the year in which the differences reverse. In accordance with accounting standards, the Company assesses the likelihood that its deferred tax assets will be realized. Deferred tax assets are reduced by a valuation allowance when, after considering all available positive and negative evidence, it is determined that it is more likely than not that some portion, or all, of the deferred tax asset will not be realized.

As of December 31, 2016, the Company had a valuation allowance of $4.1 million against deferred tax assets it estimates will not be realized. The Company will analyze its position in subsequent reporting periods, considering all available positive and negative evidence, in determining the expected realization of its deferred tax assets.

In 2016, the Company adopted ASU No. 2016-09, “Compensation – Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting,” and, accordingly, recognizes excess tax benefits for stock-based awards within income tax expense when realized. The Company applied the guidance in the new standard prospectively as of January 1, 2016. Excess tax benefits for the years ended December 31, 2015 and 2014 are recorded in additional paid-in-capital. The Company realized $1.7 million of excess tax benefits during 2016.

The Company recognizes interest and penalties related to tax matters as a component of “Selling, general and administrative expenses” in the accompanying Consolidated Statements of Comprehensive Income. As of December 31, 2016, the Company has identified no uncertain tax position and, accordingly, has not recorded any unrecognized tax benefits or associated interest and penalties.

The Company operates in multiple tax jurisdictions and, in the normal course of business, its tax returns are subject to examination by various taxing authorities. Such examinations may result in future assessments by these taxing authorities, and the Company has accrued a liability when it believes that it is not more likely than not that it will realize the benefits of tax positions that it has taken or for the amount of any tax benefit that exceeds the cumulative probability threshold in accordance with accounting standards. As of December 31, 2016, Federal tax years 2013 through 2016 remain subject to examination. The Company believes that adequate provisions have been made for all tax returns subject to examination. Sales made to foreign distributors are not taxable in any foreign jurisdictions as the Company does not have a taxable presence.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2016

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

13.

COMMITMENTS AND CONTINGENCIES

Legal Matters

The Company has lawsuits, as well as other claims, pending against it which are ordinary routine litigation and claims incidental to the business. Management has evaluated the merits of these lawsuits and claims, and believes that their ultimate resolution will not have a material effect on the Company’s consolidated financial condition, results of operations, liquidity or competitive position.

Purchase Commitments

The Company fulfills requirements for raw materials under both purchase orders and supply contracts. In the year ended December 31, 2016, the Company purchased substantially all of its reclaimed wood fiber requirements under purchase orders which do not involve long-term supply commitments. All of the Company’s scrap polyethylene purchases are under short-term supply contracts that average approximately one to two years, for which pricing is negotiated as needed, or under purchase orders that do not involve long-term supply commitments.

The wood and polyethylene supply contracts generally provide that the Company is obligated to purchase all of the wood or polyethylene a supplier provides, if the wood or polyethylene meets certain specifications. The amount of wood and polyethylene the Company is required to purchase under these contracts varies with the production of its suppliers and, accordingly, is not fixed or determinable. As of December 31, 2016, the Company has purchase commitments under material supply contracts of $20.2 million, $3.2 million, $0.35 million and $0.05 million for the years ending December 31, 2017, 2018, 2019 and 2020, respectively.

Contract Termination Costs

As of December 31, 2016, the minimum payments remaining under the Company’s lease over the years ending December 31, 2017, 2018, and 2019 are $1.9 million, $2.0 million, and $1.0 million, respectively. The net minimum receipts remaining under the Company’s existing subleases over the years ending December 31, 2017, 2018, and 2019 are $1.3 million, $1.3 million, and $0.7 million, respectively.

The following table provides information about the Company’s liability under the lease (in thousands):


	2016			2015
Beginning balance, January 1	$	2,106		$	3,033
Net rental payments		(691	)		(1,352	)
Accretion of discount		145			220
(Decrease) increase in net estimated contract termination costs		(85	)		205

Ending balance, December 31	$	1,475		$	2,106

Product Warranty

The Company continues to receive and settle claims for products manufactured at its Nevada facility prior to 2007 that exhibit surface flaking and maintains a warranty reserve to provide for the settlement of these claims. Estimating the warranty reserve for surface flaking claims requires management to estimate (1) the number of claims to be settled with payment and (2) the average cost to settle each claim.

To estimate the number of claims to be settled with payment, the Company utilizes actuarial techniques to determine a reasonable possible range of claims to be received and the percentage of those claims that will ultimately require payment. Management utilizes a range of assumptions derived from claim count history and the identification of factors influencing the claim counts to determine its best estimate of future claims for which to record a related liability. The number of claims received has declined each year since peaking in 2009, although the rate of decline has decelerated in recent years. Additionally, events such as the 2009 settlement of a class action lawsuit covering the surface defect and communications by the Company in 2013 informing homeowners of potential hazards associated with products exhibiting surface flaking that are not timely replaced, have obscured observable trends in historical claims activity. The cost per claim varies due to a number of factors, including the size of affected decks, the availability and type of replacement material used, the cost of production of replacement material and the method of claim settlement.

The Company monitors surface flaking claims activity each quarter for indications that its estimates require revision. Typically, a majority of surface flaking claims received in a year are received during the summer outdoor season, which spans the second and third quarters. It has been the Company’s practice to utilize the actuarial techniques discussed above during the third quarter, after a significant portion of all claims has been received for the fiscal year and variances to annual claims expectations are more meaningful. The number of claims received in the year ended December 31, 2016 was lower than claims received in the year ended December 31, 2015, continuing the historical year-over-year decline in incoming claims, but was higher than the Company’s expectations. Also, the average settlement cost per claim experienced in the year ended December 31, 2016 was higher than the average settlement cost per claim experienced during the year ended December 31, 2015 and higher than the Company’s expectation for 2016. As a result and after actuarial review, the Company revised its estimate and recorded an increase to the warranty reserve of $9.8 million during the third quarter of 2016. Based on the facts and circumstances at December 31, 2016, the Company believes its reserve is sufficient to cover future surface flaking obligations. The Company notes that its annual cash outflows for surface flaking claims declined by $1.5 million, or 21%, in 2016 compared to 2015, and declined by $1.7 million, or 19%, in 2015 compared to 2014.

The Company’s analysis is based on currently known facts and a number of assumptions, as discussed above, and current expectations. Projecting future events such as the number of claims to be received, the number of claims that will require payment and the average cost of claims could cause the actual warranty liabilities to be higher or lower than those projected, which could materially affect the Company’s financial condition, results of operations or cash flows. The Company estimates that the annual number of claims received will continue to decline over time and that the average cost per claim will increase slightly, primarily due to inflation. If the level of claims received or average cost per claim differs materially from expectations, it could result in additional increases or decreases to the warranty reserve and a decrease or increase in earnings and cash flows in future periods. The Company estimates that a 10% change in the expected number of remaining claims to be settled with payment or the expected cost to settle claims may result in approximately a $3.4 million change in the surface flaking warranty reserve.

The following is a reconciliation of the Company’s warranty reserve that represents amounts accrued for surface flaking claims (in thousands):


	2016			2015
Beginning balance, January 1	$	29,673		$	31,419
Changes in estimates related to pre-existing warranties		9,835			5,426
Settlements made during the period		(5,661	)		(7,172	)

Ending balance, December 31	$	33,847		$	29,673

The remainder of the Company’s warranty reserve represents amounts accrued for non-surface flaking claims.

Interim Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2016

Quarterly Financial Information Disclosure [Abstract]

Interim Financial Data (Unaudited)

14.

INTERIM FINANCIAL DATA (Unaudited)


	Three Months Ended
	December 31, 2016		September 30, 2016		June 30, 2016		March 31, 2016		December 31, 2015		September 30, 2015		June 30, 2015		March 31, 2015
	(In thousands, except share and per share data)
Net sales		95,322		106,168		146,450		131,676		89,202		94,023		136,779		120,800
Gross profit		38,113		29,945		61,410		57,627		31,955		22,143		52,524		48,247
Net income		12,629		7,787		23,725		23,706		8,086		3,744		18,715		17,553
Basic net income per share	$	0.43	$	0.27	$	0.81	$	0.80	$	0.26	$	0.12	$	0.59	$	0.55
Basic weighted average common shares outstanding		29,318,915		29,295,284		29,264,362		29,697,722		30,766,943		31,227,643		31,735,333		31,683,672
Diluted net income per share	$	0.43	$	0.26	$	0.80	$	0.79	$	0.26	$	0.12	$	0.58	$	0.55
Diluted weighted average common shares outstanding		29,543,842		29,516,718		29,477,870		29,910,292		30,966,682		31,537,010		32,142,939		32,094,828

The Company’s net sales, gross profit and income from operations have historically varied from quarter to quarter. Such variations are often attributable to seasonal trends in the demand for Trex products. The Company has historically experienced lower net sales during the fourth quarter because holidays and adverse weather conditions in certain regions reduce the level of home improvement and construction activity.

The Company elected to early adopt ASU No. 2016-09, “Compensation – Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting” (ASU No. 2016-09) in the quarterly period ended December 31, 2016, with adoption as of January 1, 2016. The effect on previously reported data for the quarterly periods ended September 30, June 30, and March 31, 2016 is presented in the below table. Also, see the related discussion in Note 2, “Summary of Significant Accounting Policies: Recently Adopted Accounting Standards,” to these Consolidated Financial Statements.


	Three Months Ended
	September 30, 2016				June 30, 2016				March 31, 2016
	As Reported		Adjusted		As Reported		Adjusted		As Reported		Adjusted
	(In thousands, except share and per share data)
Net income	$	6,898	$	7,787	$	23,279	$	23,725	$	23,402	$	23,706
Basic net income per share	$	0.24	$	0.27	$	0.80	$	0.81	$	0.79	$	0.80
Diluted net income per share	$	0.23	$	0.26	$	0.79	$	0.80	$	0.78	$	0.79
Diluted weighted average common shares outstanding		29,457,653		29,516,718		29,423,845		29,477,870		29,860,730		29,910,292

Schedule II - Valuation and Qualifying Accounts and Reserves

12 Months Ended

Dec. 31, 2016

Valuation and Qualifying Accounts [Abstract]

Schedule II - Valuation and Qualifying Accounts and Reserves

TREX COMPANY, INC.

SCHEDULE II—VALUATION AND QUALIFYING ACCOUNTS AND RESERVES

(In Thousands)


Descriptions	Balance at Beginning of Period		Additions (Reductions) Charged to Cost and Expenses		Deductions			Balance at End of Period
Year ended December 31, 2016:
Warranty reserve	$	33,522	$	10,852	$	(6,682	)	$	37,692

Income tax valuation allowance	$	4,582	$	—	$	(521	)	$	4,061

Year ended December 31, 2015:
Warranty reserve	$	33,841	$	8,515	$	(8,834	)	$	33,522

Income tax valuation allowance	$	4,465	$	117	$	—		$	4,582

Year ended December 31, 2014:
Warranty reserve	$	40,812	$	3,774	$	(10,745	)	$	33,841

Income tax valuation allowance	$	4,201	$	388	$	(124	)	$	4,465

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2016

Accounting Policies [Abstract]

Basis of Accounting

Basis of Accounting

Use of Estimates

Use of Estimates

Cash and Cash Equivalents

Cash and Cash Equivalents

Cash equivalents consist of highly liquid investments purchased with original maturities of three months or less.

Concentrations and Credit Risk

Concentrations and Credit Risk

Approximately 33%, 35%, and 38% of the Company’s materials purchases for the years ended December 31, 2016, 2015 and 2014, respectively, were purchased from its four largest suppliers.

Inventories

Inventories

Property, Plant and Equipment

Property, Plant and Equipment


Buildings			40 years
Machinery and equipment			3-11 years
Furniture and equipment			10 years
Forklifts and tractors			5 years
Computer equipment and software			5 years

Leasehold improvements are amortized over the shorter of the lease term or the estimated useful life of the asset.

Fair Value Measurement

Fair Value Measurement

•

Level 1 – Quoted prices for identical instruments in active markets.

•

Contract Termination Costs

Contract Termination Costs

Goodwill

Product Warranty

Treasury Stock

Revenue Recognition

Stock-Based Compensation

Stock-Based Compensation

Income Taxes

Income Taxes

Research and Development Costs

Research and Development Costs

Advertising Costs

Advertising Costs

For the years ended December 31, 2016, 2015 and 2014, branding expenses, including advertising expenses as described above, were $24.8 million, $23.4 million and $20.8 million, respectively.

Fair Value of Financial Instruments

Fair Value of Financial Instruments

Recently Adopted Accounting Standards

Recently Adopted Accounting Standards

•

New Accounting Standards Not Yet Adopted

New Accounting Standards Not Yet Adopted

Reclassifications

Reclassifications

Certain prior year amounts have been reclassified to conform to the current year presentation.

Inventories (Tables)

12 Months Ended

Dec. 31, 2016

Inventory Disclosure [Abstract]

Summary of Inventories, at LIFO Value

Inventories (at LIFO value) consist of the following as of December 31 (in thousands):


	2016			2015
Finished goods	$	29,686		$	24,961
Raw materials		20,231			21,384

Total FIFO (first-in, first out) inventories		49,917			46,345
Reserve to adjust inventories to LIFO value		(21,371	)		(23,241	)

Total LIFO inventories	$	28,546		$	23,104

Prepaid Expenses and Other Assets (Tables)

12 Months Ended

Dec. 31, 2016

Text Block [Abstract]

Summary of Prepaid Expenses and Other Assets

Prepaid expenses and other assets consist of the following as of December 31 (in thousands):


	2016		2015
Prepaid expenses	$	6,209	$	1,897
Income tax receivable		4,024		5,134
Assets held for sale		—		6,154
Other		167		224

Total prepaid expenses and other assets	$	10,400	$	13,409

Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2016

Property, Plant and Equipment [Abstract]

Summary of Property, Plant and Equipment

Property, plant and equipment consist of the following as of December 31 (in thousands):


	2016			2015
Building and improvements	$	47,859		$	47,209
Machinery and equipment		223,450			210,880
Furniture and fixtures		2,710			2,221
Forklifts and tractors		10,167			7,607
Computer equipment		10,481			9,575
Construction in process		4,172			11,032
Land		11,417			8,532

Total property, plant and equipment		310,256			297,056
Accumulated depreciation		(206,970	)		(196,132	)

Total property, plant and equipment, net	$	103,286		$	100,924

Accrued Expenses (Tables)

12 Months Ended

Dec. 31, 2016

Payables and Accruals [Abstract]

Summary of Accrued Expenses

Accrued expenses consist of the following (in thousands):


	2016		2015
Sales and marketing costs	$	16,707	$	11,928
Compensation and benefits		13,298		11,217
Manufacturing costs		1,799		1,732
Rent obligations		632		664
Other		2,257		3,350

Total accrued expenses	$	34,693	$	28,891

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2016

Equity [Abstract]

Computation of Basic and Diluted Earnings Per Share

The following table sets forth the computation of basic and diluted earnings per share (in thousands, except share and per share data):


	Year Ended December 31,
	2016		2015		2014
Numerator:
Net income	$	67,847	$	48,098	$	41,521

Denominator:
Basic weighted average shares outstanding		29,394,559		31,350,542		32,319,649
Effect of dilutive securities:
SARS and options		125,119		197,299		262,730
Restricted stock		92,991		134,668		168,695

Diluted weighted average shares outstanding		29,612,669		31,682,509		32,751,074

Basic earnings per share	$	2.31	$	1.53	$	1.28

Diluted earnings per share	$	2.29	$	1.52	$	1.27

Antidilutive Securities Excluded from Computation of Earnings Per Share

The computation of diluted earnings per share excludes the following potentially dilutive securities because the effect would be anti-dilutive:


	Year Ended December 31,
	2016		2015		2014
Restricted stock and stock options		12		501		2,633
Stock appreciation rights		4,631		5,828		1,969

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2016

Summary of Stock-Based Compensation Expense

The following table summarizes the Company’s stock-based compensation expense for the years ended December 31, 2016, 2015 and 2014 (in thousands):


	Year Ended December 31,
	2016		2015		2014
Time-based restricted stock and time-based restricted stock units	$	2,281	$	2,704	$	2,974
Performance-based restricted stock and performance-based restricted stock units		2,210		1,562		727
Stock appreciation rights		184		525		1,035
Employee stock purchase plan		113		70		71

Total stock-based compensation	$	4,788	$	4,861	$	4,807

Summary of Assumptions Used to Estimate Fair Value of Each SAR

The fair value of each SAR is estimated on the date of grant using a Black-Scholes option-pricing model. There were no SARs issued in the year ended December 31, 2016. For SARs issued in the years ended December 31, 2015 and 2014, respectively, the assumptions shown in the following table were used:


	December 31,
	2015			2014
Dividend yield		0	%		0	%
Average risk-free interest rate		1.6	%		1.7	%
Expected term (years)		5			5
Expected volatility		42.9	%		52.6	%

SAR Activity

SAR activity under the Plan and all predecessor stock incentive plans is as follows:


	SARs			Weighted-Average Grant Price Per Share		Weighted- Average Remaining Contractual Life (Years)		Aggregate Intrinsic Value as of December 31, 2016
Outstanding at December 31, 2013		739,194		$	12.93
Granted		3,866		$	37.88
Exercised		(218,826	)	$	10.96
Canceled		(8,404	)	$	4.74

Outstanding at December 31, 2014		515,830		$	13.98
Granted		15,585		$	41.19
Exercised		(263,626	)	$	13.86
Canceled		(5,712	)	$	21.94

Outstanding at December 31, 2015		262,077		$	13.13
Granted		—		$	—
Exercised		(124,352	)	$	11.09
Canceled		—		$	—

Outstanding at December 31, 2016		137,725		$	19.57		5.6	$	6,174,886
Vested at December 31, 2016		127,469		$	17.83		5.4	$	5,936,639
Exercisable at December 31, 2016		127,469		$	17.83		5.4	$	5,936,639

Stock Option Activity

Stock option activity under the Plan and all predecessor stock incentive plans is as follows:


	Options			Weighted-Average Exercise Price Per Share
Outstanding at December 31, 2013		42,288		$	20.05
Granted		—		$	—
Exercised		(27,942	)	$	35.73
Canceled		(1,188	)	$	17.92

Outstanding at December 31, 2014		13,158		$	23.36
Granted		—		$	—
Exercised		(13,158	)	$	50.37
Canceled		—		$	—

Outstanding at December 31, 2015		—		$	—

Time-Based Restricted Stock [Member]

Restricted Stock Activity

Time-based restricted stock activity under the Plan and all predecessor stock incentive plans is as follows:


	Time-based Restricted Stock			Weighted-Average Grant Price Per Share
Nonvested at December 31, 2013		382,974		$	13.78
Granted		66,511		$	32.70
Vested		(116,641	)	$	33.73
Forfeited		(3,282	)	$	16.61

Nonvested at December 31, 2014		329,562		$	18.89
Granted		57,598		$	43.81
Vested		(230,704	)	$	42.37
Forfeited		(48,549	)	$	20.20

Nonvested at December 31, 2015		107,907		$	29.43
Granted		57,874		$	37.64
Vested		(43,848	)	$	42.34
Forfeited		(133	)	$	43.89

Nonvested at December 31, 2016		121,800		$	31.59

Performance-Based Restricted Stock [Member]

Restricted Stock Activity

Performance-based restricted stock activity under the Plan is as follows:


	Performance-based Restricted Stock and Performance-based Restricted Stock Units			Weighted-Average Grant Price Per Share
Nonvested at December 31, 2014		42,676		$	33.72
Granted		34,638		$	43.89
Vested		(35,679	)	$	41.91
Forfeited		(12,538	)	$	38.12

Nonvested at December 31, 2015		29,097		$	39.38
Granted		44,925		$	35.83
Vested		(14,949	)	$	35.71
Forfeited		(657	)	$	33.72

Nonvested at December 31, 2016		58,416		$	36.63

Leases (Tables)

12 Months Ended

Dec. 31, 2016

Leases [Abstract]

Minimum Annual Payments Under Non-Cancelable Leases

Minimum annual payments under these non-cancelable leases as of December 31, 2016 were as follows (in thousands):


Year Ending December 31,
2017	$	9,606
2018		9,271
2019		8,205
2020		6,477
2021		6,170
Thereafter		18,659

Total minimum lease payments	$	58,388

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Income Tax Provision (Benefit)

Income tax provision (benefit) for the years ended December 31, 2016, 2015 and 2014 consists of the following (in thousands):


	Year Ended December 31,
	2016		2015		2014
Current income tax provision:
Federal	$	26,752	$	25,105	$	18,722
State		2,798		2,560		3,131

		29,550		27,665		21,853

Deferred income tax provision:
Federal		5,217		987		3,118
State		216		37		456

		5,433		1,024		3,574

Total income tax provision	$	34,983	$	28,689	$	25,427

Reconciliation of Differences between Income Tax Provision and Income Tax Determined by Applying US Federal Statutory Rate

The income tax provision differs from the amount of income tax determined by applying the U.S. Federal statutory rate to income before taxes as a result of the following (in thousands):


	Year Ended December 31,
	2016			2015			2014
U.S. Federal statutory taxes	$	35,990		$	26,876		$	23,432
State and local taxes, net of U.S. Federal benefit		3,747			2,806			2,856
Permanent items		396			1,308			249
Excess tax benefits from vesting or settlement of stock compensation awards		(1,749	)		—			—
Domestic production activities deduction		(2,740	)		(2,262	)		(1,117	)
Federal credits		(488	)		(328	)		(214	)
Other		(173	)		289			221

Total income tax provision	$	34,983		$	28,689		$	25,427

Schedule of Deferred Tax Assets and Liabilities

Deferred tax assets and liabilities as of December 31, 2016 and 2015 consist of the following (in thousands):


	As of December 31,
	2016			2015
Deferred tax assets:
Net operating losses	$	93		$	138
Warranty reserve		14,510			12,904
Stock-based compensation		2,186			1,554
Accruals not currently deductible and other		2,261			6,195
Inventories		5,785			4,406
State tax credit carryforwards		4,020			4,350

Gross deferred tax assets, before valuation allowance		28,855			29,547
Valuation allowance		(4,061	)		(4,582	)

Gross deferred tax assets, after valuation allowance		24,794			24,965

Deferred tax liabilities:
Depreciation and other		(25,688	)		(20,426	)

Gross deferred tax liabilities		(25,688	)		(20,426	)

Net deferred tax (liability) asset	$	(894	)	$	4,539

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2016

Commitments and Contingencies Disclosure [Abstract]

Summary of Liability Related to Lease

The following table provides information about the Company’s liability under the lease (in thousands):


	2016			2015
Beginning balance, January 1	$	2,106		$	3,033
Net rental payments		(691	)		(1,352	)
Accretion of discount		145			220
(Decrease) increase in net estimated contract termination costs		(85	)		205

Ending balance, December 31	$	1,475		$	2,106

Summary of Reconciliation of Company's Warranty Reserve that Represents Amounts Accrued for Surface Flaking Claims

The following is a reconciliation of the Company’s warranty reserve that represents amounts accrued for surface flaking claims (in thousands):


	2016			2015
Beginning balance, January 1	$	29,673		$	31,419
Changes in estimates related to pre-existing warranties		9,835			5,426
Settlements made during the period		(5,661	)		(7,172	)

Ending balance, December 31	$	33,847		$	29,673

Interim Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2016

Quarterly Financial Information Disclosure [Abstract]

Summary of Interim Financial Data


	Three Months Ended
	December 31, 2016		September 30, 2016		June 30, 2016		March 31, 2016		December 31, 2015		September 30, 2015		June 30, 2015		March 31, 2015
	(In thousands, except share and per share data)
Net sales		95,322		106,168		146,450		131,676		89,202		94,023		136,779		120,800
Gross profit		38,113		29,945		61,410		57,627		31,955		22,143		52,524		48,247
Net income		12,629		7,787		23,725		23,706		8,086		3,744		18,715		17,553
Basic net income per share	$	0.43	$	0.27	$	0.81	$	0.80	$	0.26	$	0.12	$	0.59	$	0.55
Basic weighted average common shares outstanding		29,318,915		29,295,284		29,264,362		29,697,722		30,766,943		31,227,643		31,735,333		31,683,672
Diluted net income per share	$	0.43	$	0.26	$	0.80	$	0.79	$	0.26	$	0.12	$	0.58	$	0.55
Diluted weighted average common shares outstanding		29,543,842		29,516,718		29,477,870		29,910,292		30,966,682		31,537,010		32,142,939		32,094,828

Schedule of Effect on Previously Reported Quarterly Data

The effect on previously reported data for the quarterly periods ended September 30, June 30, and March 31, 2016 is presented in the below table. Also, see the related discussion in Note 2, “Summary of Significant Accounting Policies: Recently Adopted Accounting Standards,” to these Consolidated Financial Statements.


	Three Months Ended
	September 30, 2016				June 30, 2016				March 31, 2016
	As Reported		Adjusted		As Reported		Adjusted		As Reported		Adjusted
	(In thousands, except share and per share data)
Net income	$	6,898	$	7,787	$	23,279	$	23,725	$	23,402	$	23,706
Basic net income per share	$	0.24	$	0.27	$	0.80	$	0.81	$	0.79	$	0.80
Diluted net income per share	$	0.23	$	0.26	$	0.79	$	0.80	$	0.78	$	0.79
Diluted weighted average common shares outstanding		29,457,653		29,516,718		29,423,845		29,477,870		29,860,730		29,910,292

Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016 USD ($) ft² Customer Institution Supplier	Dec. 31, 2015 USD ($) Customer	Dec. 31, 2014 USD ($) Customer	Dec. 31, 2010 USD ($)
Schedule Of Significant Accounting Policies [Line Items]
Charge to earning to fully reserve the equity investment and note				$ 2,400,000
Maximum term of original maturities to classify as cash equivalent	3 months
Number of financial institutions where deposits are maintained \| Institution	1
Valuation allowance	$ 0	$ 0
Number of customers that accounted for 10% or more of net sales \| Customer	2	1	1
Number of customer accounted for 10% or more account receivable \| Customer	4
Number of largest raw material suppliers \| Supplier	4
Excess of the replacement cost of inventory over the LIFO value of inventory	$ 21,371,000	$ 23,241,000
Annual impairment test of goodwill	0	0	$ 0
Goodwill	10,500,000
Valuation allowance	4,061,000	4,582,000
Research and Development costs	3,700,000	1,500,000	2,300,000
Prepaid expenses for production costs of advertising	2,400,000	800,000
Branding Expenses	24,800,000	23,400,000	20,800,000
Income tax expense (benefit)	34,983,000	$ 28,689,000	$ 25,427,000
Accounting Standards Update 2016-09 [Member]
Schedule Of Significant Accounting Policies [Line Items]
Income tax expense (benefit)	$ (1,700,000)
Contract Termination [Member]
Schedule Of Significant Accounting Policies [Line Items]
Lease square feet \| ft²	55,047
Contract Termination [Member] \| Dulles, Virginia [Member]
Schedule Of Significant Accounting Policies [Line Items]
Expiration date of reconsidered corporate headquarters lease	Jun. 30, 2019
Lease square feet \| ft²	55,047
Residential Use [Member]
Schedule Of Significant Accounting Policies [Line Items]
Warranty period	25 years
Commercial Use [Member]
Schedule Of Significant Accounting Policies [Line Items]
Warranty period	10 years
Trex Signature Railing [Member] \| Residential Use [Member]
Schedule Of Significant Accounting Policies [Line Items]
Warranty period	25 years
Trex Signature Railing [Member] \| Commercial Use [Member]
Schedule Of Significant Accounting Policies [Line Items]
Warranty period	25 years
Transcend, Enhance, Select and Universal Fascia Product [Member] \| Residential Use [Member]
Schedule Of Significant Accounting Policies [Line Items]
Warranty period	25 years
Transcend, Enhance, Select and Universal Fascia Product [Member] \| Commercial Use [Member]
Schedule Of Significant Accounting Policies [Line Items]
Warranty period	10 years
Sales Revenue, Net [Member] \| Customer Concentration Risk [Member] \| Minimum [Member]
Schedule Of Significant Accounting Policies [Line Items]
Concentration risk as percentage of total	10.00%	10.00%	10.00%
Sales Revenue, Net [Member] \| Customer Concentration Risk [Member] \| Customer One [Member]
Schedule Of Significant Accounting Policies [Line Items]
Concentration risk as percentage of total	39.00%	27.00%	24.00%
Accounts Receivable [Member] \| Customer Concentration Risk [Member] \| Customer One [Member]
Schedule Of Significant Accounting Policies [Line Items]
Concentration risk as percentage of total	30.00%
Accounts Receivable [Member] \| Customer Concentration Risk [Member] \| Customer Two [Member]
Schedule Of Significant Accounting Policies [Line Items]
Concentration risk as percentage of total	16.00%
Accounts Receivable [Member] \| Customer Concentration Risk [Member] \| Customer Three [Member]
Schedule Of Significant Accounting Policies [Line Items]
Concentration risk as percentage of total	14.00%
Accounts Receivable [Member] \| Customer Concentration Risk [Member] \| Customer Four [Member]
Schedule Of Significant Accounting Policies [Line Items]
Concentration risk as percentage of total	13.00%
Raw Materials [Member] \| Supplier Concentration Risk [Member]
Schedule Of Significant Accounting Policies [Line Items]
Concentration risk as percentage of total	33.00%	35.00%	38.00%
Denplax [Member]
Schedule Of Significant Accounting Policies [Line Items]
Holding company's interest in Denplax	35.00%

Summary of Significant Accounting Policies - Estimated Useful Lives of Property Plant and Equipment (Detail)	12 Months Ended
	Dec. 31, 2016
Buildings [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment estimated useful life	40 years
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment estimated useful life	10 years
Forklifts and Tractors [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment estimated useful life	5 years
Computer Equipment and Software [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment estimated useful life	5 years
Minimum [Member] \| Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment estimated useful life	3 years
Maximum [Member] \| Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment estimated useful life	11 years

Inventories - Summary of Inventories, at LIFO Value (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Inventory Disclosure [Abstract]
Finished goods	$ 29,686	$ 24,961
Raw materials	20,231	21,384
Total FIFO (first-in, first out) inventories	49,917	46,345
Reserve to adjust inventories to LIFO value	(21,371)	(23,241)
Total LIFO inventories	$ 28,546	$ 23,104

Inventories - Additional Information (Detail)	12 Months Ended
Inventories - Additional Information (Detail)	Dec. 31, 2016 USD ($)
Inventory Disclosure [Abstract]
Benefit recognized, to cost of sales, under the LIFO method due to reduction in inventory	$ 0

Prepaid Expenses and Other Assets - Summary of Prepaid Expenses and Other Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Prepaid Expense and Other Assets [Abstract]
Prepaid expenses	$ 6,209	$ 1,897
Income tax receivable	4,024	5,134
Assets held for sale		6,154
Other	167	224
Total prepaid expenses and other assets	$ 10,400	$ 13,409

Property, Plant and Equipment - Summary of Property, Plant and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 310,256	$ 297,056
Accumulated depreciation	(206,970)	(196,132)
Total property, plant and equipment, net	103,286	100,924
Building and Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	47,859	47,209
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	223,450	210,880
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	2,710	2,221
Forklifts and Tractors [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	10,167	7,607
Computer Equipment and Software [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	10,481	9,575
Construction in Process [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	4,172	11,032
Land [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 11,417	$ 8,532

Property, Plant and Equipment - Additional Information (Detail) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2016 USD ($)	Dec. 31, 2016 USD ($) a	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		$ 310,256	$ 297,056
Depreciation expense		14,200	14,300	$ 14,800
Proceeds from sales of property, plant and equipment		4,349	35	66
Gain (loss) on disposal of property, plant and equipment		$ 185	(649)	$ (158)
Olive Branch Assets [Member]
Property, Plant and Equipment [Line Items]
Loss on asset reclassification			500
Proceeds from sales of property, plant and equipment	$ 4,200
Gain (loss) on disposal of property, plant and equipment	$ 100
Area of land owned \| a		62
Construction in Process [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		$ 4,172	$ 11,032

Accrued Expenses - Summary of Accrued Expenses (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Payables and Accruals [Abstract]
Sales and marketing costs	$ 16,707	$ 11,928
Compensation and benefits	13,298	11,217
Manufacturing costs	1,799	1,732
Rent obligations	632	664
Other	2,257	3,350
Total accrued expenses	$ 34,693	$ 28,891

Debt - Additional Information (Detail)		3 Months Ended	12 Months Ended
Debt - Additional Information (Detail)	Jan. 12, 2016	Dec. 31, 2016 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Nov. 20, 2014 USD ($)	Jan. 06, 2012 USD ($)
Line of Credit Facility [Line Items]
Remaining available borrowing capacity		$ 200,000,000	$ 200,000,000
Company indebtedness		0	$ 0	$ 7,000,000
Third Amended and Restated Credit Agreement [Member]
Line of Credit Facility [Line Items]
Termination date of the Credit Agreement			Jan. 12, 2021
Third Amended and Restated Credit Agreement [Member] \| Federal Funds Rate [Member]
Line of Credit Facility [Line Items]
Interest rate	0.50%
Third Amended and Restated Credit Agreement [Member] \| Eurodollar Rate Loans [Member]
Line of Credit Facility [Line Items]
Interest rate	1.00%
Second Amended and Restated Credit Agreement [Member]
Line of Credit Facility [Line Items]
Termination date of the Credit Agreement			Nov. 20, 2019
Credit facility covenant terms			The material financial covenants and restrictions do not permit the Company's fixed charge coverage ratio to be less than 1.5 to 1.0 and do not permit the Company's consolidated debt to consolidated EBITDA ratio to exceed 3.0 to 1.0, measured as of the end of each fiscal quarter (and in the case of Consolidated EBITDA, for the four-quarter period ending on such date).
Revolver Loans [Member] \| As Reported [Member]
Line of Credit Facility [Line Items]
Revolving loans in a collective maximum principal amount						$ 100,000,000
Revolver Loans Portion Effective January 1 through June 30 [Member] \| Third Amended and Restated Credit Agreement [Member]
Line of Credit Facility [Line Items]
Revolving loans in a collective maximum principal amount		250,000,000	$ 250,000,000
Revolver Loans Portion Effective January 1 through June 30 [Member] \| Second Amended and Restated Credit Agreement [Member]
Line of Credit Facility [Line Items]
Revolving loans in a collective maximum principal amount		150,000,000	150,000,000
Revolver Loans Portion Effective July 1 through December 31 [Member] \| Third Amended and Restated Credit Agreement [Member]
Line of Credit Facility [Line Items]
Revolving loans in a collective maximum principal amount		200,000,000	200,000,000
Revolver Loans Portion Effective July 1 through December 31 [Member] \| Second Amended and Restated Credit Agreement [Member]
Line of Credit Facility [Line Items]
Revolving loans in a collective maximum principal amount		$ 100,000,000	100,000,000
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Interest rate on the revolving credit facility				1.39%
Revolving Credit Facility [Member] \| Second Amended and Restated Credit Agreement [Member] \| Minimum [Member]
Line of Credit Facility [Line Items]
Fixed charge coverage ratio as per credit agreement		1.5
Revolving Credit Facility [Member] \| Second Amended and Restated Credit Agreement [Member] \| Maximum [Member]
Line of Credit Facility [Line Items]
Consolidated debt to earnings before interest taxes depreciation amortization ratio as per the credit agreement		3.0
Revolving Credit Facility [Member] \| Letter of Credit Facility Sublimit [Member]
Line of Credit Facility [Line Items]
Revolving loans in a collective maximum principal amount		$ 15,000,000	15,000,000		$ 15,000,000
Revolving Credit Facility [Member] \| Swing Advance Loan Sublimit [Member]
Line of Credit Facility [Line Items]
Revolving loans in a collective maximum principal amount		$ 5,000,000	$ 5,000,000		$ 5,000,000

Stockholders' Equity - Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Numerator:
Net income	$ 12,629	$ 7,787	$ 23,725	$ 23,706	$ 8,086	$ 3,744	$ 18,715	$ 17,553	$ 67,847	$ 48,098	$ 41,521
Denominator:
Basic weighted average shares outstanding	29,318,915	29,295,284	29,264,362	29,697,722	30,766,943	31,227,643	31,735,333	31,683,672	29,394,559	31,350,542	32,319,649
Effect of dilutive securities:
Diluted weighted average shares outstanding	29,543,842	29,516,718	29,477,870	29,910,292	30,966,682	31,537,010	32,142,939	32,094,828	29,612,669	31,682,509	32,751,074
Basic earnings per share	$ 0.43	$ 0.27	$ 0.81	$ 0.80	$ 0.26	$ 0.12	$ 0.59	$ 0.55	$ 2.31	$ 1.53	$ 1.28
Diluted earnings per share	$ 0.43	$ 0.26	$ 0.80	$ 0.79	$ 0.26	$ 0.12	$ 0.58	$ 0.55	$ 2.29	$ 1.52	$ 1.27
Stock Appreciation Rights and Options [Member]
Effect of dilutive securities:
Dilutive securities									125,119	197,299	262,730
Restricted Stock [Member]
Effect of dilutive securities:
Dilutive securities									92,991	134,668	168,695

Stockholders' Equity - Antidilutive Securities Excluded from Computation of Earnings Per Share (Detail) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Restricted Stock and Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the computation of diluted earnings per share	12	501	2,633
Stock Appreciation Rights [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the computation of diluted earnings per share	4,631	5,828	1,969

Stockholders' Equity - Additional Information (Detail) - USD ($)			12 Months Ended
	Feb. 16, 2017	Oct. 22, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Oct. 23, 2014	Feb. 19, 2014
Equity, Class of Treasury Stock [Line Items]
Common stock repurchase program, termination date		Oct. 22, 2015
Subsequent Event [Member]
Equity, Class of Treasury Stock [Line Items]
Number of shares repurchased by the Company	0
Common Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Common stock repurchase program, authorized shares						2,000,000
Common Stock [Member] \| Subsequent Event [Member]
Equity, Class of Treasury Stock [Line Items]
Common stock repurchase program, authorized shares	2,961,000
October 2014 Stock Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Number of shares repurchased by the Company				1,134,300
Value of shares repurchased by the Company				$ 45,200,000
October 2015 Stock Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Number of shares repurchased by the Company			1,578,952
Value of shares repurchased by the Company			$ 53,300,000
Common stock repurchase program, termination date		Dec. 31, 2016
October 2015 Stock Repurchase Program \| Common Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Common stock repurchase program, authorized shares		3,150,000
February 2014 Stock Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Common stock repurchase program, authorized amount							$ 50,000,000
Number of shares repurchased by the Company					1,657,919
Value of shares repurchased by the Company					$ 50,000,000

Stock-Based Compensation - Additional Information (Detail) - USD ($)		12 Months Ended
	Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Approximate number of shares employees purchased under the Employee Stock Purchase Plan		422,687
Stock Options Outstanding, Number	0	0	0
2014 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total aggregate number of shares of common stock that may be issued	6,420,000	6,420,000
Performance-Based Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		3 years
Unrecognized compensation cost related to unvested awards	$ 1,200,000	$ 1,200,000	$ 600,000
Compensation cost recognition period for unvested awards	2 years
Number of shares or rights issued		44,925	34,638
Performance-Based Restricted Stock [Member] \| Share-Based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based Compensation vesting percentage		33.33%
Performance-Based Restricted Stock [Member] \| Share-Based Compensation Award, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based Compensation vesting percentage		33.33%
Performance-Based Restricted Stock [Member] \| Share-Based Compensation Award, Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based Compensation vesting percentage		33.33%
Stock Appreciation Rights [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to unvested awards	$ 0	$ 0
Maximum contractual term		10 years
Fair value assumptions method used		Black-Scholes option-pricing model
Number of shares or rights issued		0
Weighted-average fair value of grants			$ 16.26	$ 17.78
Time-Based Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to unvested awards	$ 1,500,000	$ 1,500,000
Compensation cost recognition period for unvested awards	1 year 7 months 6 days
Total fair value of restricted shares vested		$ 1,700,000	$ 9,800,000	$ 3,900,000
Number of shares or rights issued		57,874	57,598	66,511
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total aggregate number of shares of common stock that may be issued	600,000	600,000
Percentage of market price on lesser of either first day of calendar quarter or last day of calendar quarter for purchase price		85.00%
Percentage of gross compensation eligible employees may elect to participate in the plan	15.00%	15.00%
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum contractual term		10 years
Minimum [Member] \| Performance-Based Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of target number of shares that will vest		0.00%
Maximum [Member] \| Performance-Based Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of target number of shares that will vest		200.00%	200.00%

Stock-Based Compensation - Summary of Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 4,788	$ 4,861	$ 4,807
Time Based Restricted Stock and Time Based Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	2,281	2,704	2,974
Performance Based Restricted Stock and Performance Based Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	2,210	1,562	727
Stock Appreciation Rights [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	184	525	1,035
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 113	$ 70	$ 71

Stock-Based Compensation - Time-Based Restricted Stock Activity (Detail) - Time-Based Restricted Stock [Member] - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule Of Restricted Stock Activity [Line Items]
Nonvested, Shares, Beginning Balance	107,907	329,562	382,974
Time-based Restricted Stock, Granted	57,874	57,598	66,511
Time-based Restricted Stock, Vested	(43,848)	(230,704)	(116,641)
Time-based Restricted Stock, Forfeited	(133)	(48,549)	(3,282)
Nonvested, Shares, Ending Balance	121,800	107,907	329,562
Nonvested, Weighted-Average Grant Price Per Share, Beginning Balance	$ 29.43	$ 18.89	$ 13.78
Weighted-Average Grant Price Per Share, Granted	37.64	43.81	32.70
Weighted-Average Grant Price Per Share, Vested	42.34	42.37	33.73
Weighted-Average Grant Price Per Share, Forfeited	43.89	20.20	16.61
Nonvested, Weighted-Average Grant Price Per Share, Ending Balance	$ 31.59	$ 29.43	$ 18.89

Stock-Based Compensation - Performance-Based Restricted Stock Activity (Detail) - Performance-Based Restricted Stock [Member] - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Schedule Of Restricted Stock Activity [Line Items]
Nonvested, Shares, Beginning Balance	29,097	42,676
Performance-based Restricted Stock, Granted	44,925	34,638
Performance-based Restricted Stock, Vested	(14,949)	(35,679)
Performance-based Restricted Stock, Forfeited	(657)	(12,538)
Nonvested, Shares, Ending Balance	58,416	29,097
Nonvested, Weighted-Average Grant Price Per Share, Beginning Balance	$ 39.38	$ 33.72
Weighted-Average Grant Price Per Share, Granted	35.83	43.89
Weighted-Average Grant Price Per Share, Vested	35.71	41.91
Weighted-Average Grant Price Per Share, Forfeited	33.72	38.12
Nonvested, Weighted-Average Grant Price Per Share, Ending Balance	$ 36.63	$ 39.38

Stock-Based Compensation - Summary of Assumptions Used to Estimate Fair Value of Each SAR (Detail) - Stock Appreciation Rights [Member]	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Share Based Compensation Arrangement by Share Based Payment Award Fair Value Assumptions and Methodology [Line Items]
Dividend yield	0.00%	0.00%
Average risk-free interest rate	1.60%	1.70%
Expected term (years)	5 years	5 years
Expected volatility	42.90%	52.60%

Stock-Based Compensation - SAR Activity (Detail) - Stock Appreciation Rights [Member] - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule Of Stock Appreciation Rights Activity [Line Items]
SARs Outstanding, Beginning Balance	262,077	515,830	739,194
Granted, SARs		15,585	3,866
Exercised, SARs	(124,352)	(263,626)	(218,826)
Canceled, SARs		(5,712)	(8,404)
Shares Outstanding, SARs, Ending Balance	137,725	262,077	515,830
Outstanding, Weighted Average Grant Price Per Share, Beginning Balance	$ 13.13	$ 13.98	$ 12.93
Vested, SARs	127,469
Granted, Weighted Average Grant Price Per Share		41.19	37.88
Exercisable, SARs	127,469
Exercised, Weighted Average Grant Price Per Share	$ 11.09	13.86	10.96
Canceled, Weighted Average Grant Price Per Share		21.94	4.74
Outstanding, Weighted Average Grant Price Per Share, Ending Balance	19.57	$ 13.13	$ 13.98
Vested, Weighted Average Grant Price Per Share	17.83
Exercisable, Weighted Average Grant Price Per Share	$ 17.83
Weighted Average Remaining Contractual Life, Outstanding	5 years 7 months 6 days
Weighted Average Remaining Contractual Life, Vested	5 years 4 months 24 days
Weighted Average Remaining Contractual Life, Exercisable	5 years 4 months 24 days
Aggregate Intrinsic Value, Outstanding	$ 6,174,886
Aggregate Intrinsic Value, Vested	5,936,639
Aggregate Intrinsic Value, Exercisable	$ 5,936,639

Stock-Based Compensation - Stock Option Activity (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Outstanding Options, Beginning Balance	13,158	42,288
Options Granted	0	0
Options Exercised	(13,158)	(27,942)
Options Canceled		(1,188)
Outstanding Options, Ending Balance		13,158
Weighted Average Exercise Price Per Share, Outstanding, Beginning Balance	$ 23.36	$ 20.05
Weighted Average Exercise Price Per Share, Granted	0	0
Weighted Average Exercise Price Per Share, Exercised	$ 50.37	35.73
Weighted Average Exercise Price Per Share, Canceled		17.92
Weighted Average Exercise Price Per Share, Outstanding, Ending Balance		$ 23.36

Leases - Minimum Annual Payments Under Non-Cancelable Leases (Detail) $ in Thousands	Dec. 31, 2016 USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2017	$ 9,606
2018	9,271
2019	8,205
2020	6,477
2021	6,170
Thereafter	18,659
Total minimum lease payments	$ 58,388

Employee Benefit Plans - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Percentage of employee's contribution to the plan up to 6% of base salary matched by the Company	100.00%
Employer's contribution percentage	6.00%
Employer's contribution	$ 2.5	$ 2.2	$ 2.0

Income Taxes - Income Tax Provision (Benefit) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current income tax provision:
Federal	$ 26,752	$ 25,105	$ 18,722
State	2,798	2,560	3,131
Total	29,550	27,665	21,853
Deferred income tax provision:
Federal	5,217	987	3,118
State	216	37	456
Total	5,433	1,024	3,574
Total income tax provision	$ 34,983	$ 28,689	$ 25,427

Income Taxes - Reconciliation of Differences between Income Tax Provision and Income Tax Determined by Applying US Federal Statutory Rate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Effective Income Tax Rate Reconciliation, Amount [Abstract]
U.S. Federal statutory taxes	$ 35,990	$ 26,876	$ 23,432
State and local taxes, net of U.S. Federal benefit	3,747	2,806	2,856
Permanent items	396	1,308	249
Excess tax benefits from vesting or settlement of stock compensation awards	(1,749)
Domestic production activities deduction	(2,740)	(2,262)	(1,117)
Federal credits	(488)	(328)	(214)
Other	(173)	289	221
Total income tax provision	$ 34,983	$ 28,689	$ 25,427

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Net operating losses	$ 93	$ 138
Warranty reserve	14,510	12,904
Stock-based compensation	2,186	1,554
Accruals not currently deductible and other	2,261	6,195
Inventories	5,785	4,406
State tax credit carryforwards	4,020	4,350
Gross deferred tax assets, before valuation allowance	28,855	29,547
Valuation allowance	(4,061)	(4,582)
Gross deferred tax assets, after valuation allowance	24,794	24,965
Deferred tax liabilities:
Depreciation and other	(25,688)	(20,426)
Gross deferred tax liabilities	(25,688)	(20,426)
Net deferred tax liability	$ (894)
Net deferred tax asset		$ 4,539

Income Taxes - Additional Information (Detail)	12 Months Ended
Income Taxes - Additional Information (Detail)	Dec. 31, 2016 USD ($) Tax_Positions	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Income Tax Contingency [Line Items]
Valuation allowance	$ 4,061,000	$ 4,582,000
Income tax expense (benefit)	$ 34,983,000	$ 28,689,000	$ 25,427,000
Unrecognized tax benefits number of tax matters \| Tax_Positions	0
Unrecognized tax benefits related to identified uncertain tax positions	$ 0
Accounting Standards Update 2016-09 [Member]
Income Tax Contingency [Line Items]
Income tax expense (benefit)	$ (1,700,000)
Earliest Tax Year [Member] \| Federal Tax Jurisdiction [Member]
Income Tax Contingency [Line Items]
Tax years subject to examination		2013
Latest Tax Year [Member] \| Federal Tax Jurisdiction [Member]
Income Tax Contingency [Line Items]
Tax years subject to examination		2016

Commitments and Contingencies - Additional Information (Detail) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($) ft²	Dec. 31, 2015 USD ($)
Schedule Of Commitments And Contingencies [Line Items]
Minimum payments, 2017		$ 9,606
Minimum payments, 2018		9,271
Minimum payments, 2019		8,205
Change in warranty reserve for disclosure purposes only		$ 3,400
Minimum [Member]
Schedule Of Commitments And Contingencies [Line Items]
Average period for PE material purchases under short-term supply contracts for which pricing is negotiated as needed		1 year
Maximum [Member]
Schedule Of Commitments And Contingencies [Line Items]
Average period for PE material purchases under short-term supply contracts for which pricing is negotiated as needed		2 years
Surface Flaking Warranty Reserve [Member]
Schedule Of Commitments And Contingencies [Line Items]
Increase in warranty reserve	$ 9,800	$ 9,835	$ 5,426
Change in percentage of annual cash outflow for surface flaking claims declined		21.00%	19.00%
Change in annual cash outflow for surface flaking claims declined		$ 1,500	$ 1,700
Percentage change in warranty claims used as a threshold for disclosure		10.00%
Residential Use [Member]
Schedule Of Commitments And Contingencies [Line Items]
Warranty period		25 years
Commercial Use [Member]
Schedule Of Commitments And Contingencies [Line Items]
Warranty period		10 years
Transcend, Enhance, Select and Universal Fascia Product [Member] \| Residential Use [Member]
Schedule Of Commitments And Contingencies [Line Items]
Warranty period		25 years
Transcend, Enhance, Select and Universal Fascia Product [Member] \| Commercial Use [Member]
Schedule Of Commitments And Contingencies [Line Items]
Warranty period		10 years
Trex Signature Railing [Member] \| Residential Use [Member]
Schedule Of Commitments And Contingencies [Line Items]
Warranty period		25 years
Trex Signature Railing [Member] \| Commercial Use [Member]
Schedule Of Commitments And Contingencies [Line Items]
Warranty period		25 years
Sublease [Member]
Schedule Of Commitments And Contingencies [Line Items]
Net minimum receipts remaining under the Company's existing subleases for 2017		$ 1,300
Net minimum receipts remaining under the Company's existing subleases for 2018		1,300
Net minimum receipts remaining under the Company's existing subleases for 2019		$ 700
Contract Termination [Member]
Schedule Of Commitments And Contingencies [Line Items]
Lease square feet \| ft²		55,047
Minimum payments, 2017		$ 1,900
Minimum payments, 2018		2,000
Minimum payments, 2019		1,000
Waste Wood And Pe Material Supply Contracts [Member]
Schedule Of Commitments And Contingencies [Line Items]
Purchase commitment		20,200
Purchase commitment, due in second year		3,200
Purchase commitment, due in third year		350
Purchase commitment, due in fourth year		$ 50

Commitments and Contingencies - Summary of Liability Related to Lease (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Beginning balance	$ 2,106	$ 3,033
Net rental payments	(691)	(1,352)
Accretion of discount	145	220
(Decrease) increase in net estimated contract termination costs	(85)	205
Ending balance	$ 1,475	$ 2,106

Commitments and Contingencies - Summary of Reconciliation of Company's Warranty Reserve that Represents Amounts Accrued for Surface Flaking Claims (Detail) - Surface Flaking Warranty Reserve [Member] - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Product Warranty Liability [Line Items]
Beginning balance		$ 29,673	$ 31,419
Changes in estimates related to pre-existing warranties	$ 9,800	9,835	5,426
Settlements made during the period		(5,661)	(7,172)
Ending balance		$ 33,847	$ 29,673

Interim Financial Data (Unaudited) - Summary of Interim Financial Data (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Data [Abstract]
Net sales	$ 95,322	$ 106,168	$ 146,450	$ 131,676	$ 89,202	$ 94,023	$ 136,779	$ 120,800	$ 479,616	$ 440,804	$ 391,660
Gross profit	38,113	29,945	61,410	57,627	31,955	22,143	52,524	48,247	187,095	154,869	140,196
Net income	$ 12,629	$ 7,787	$ 23,725	$ 23,706	$ 8,086	$ 3,744	$ 18,715	$ 17,553	$ 67,847	$ 48,098	$ 41,521
Basic net income per share	$ 0.43	$ 0.27	$ 0.81	$ 0.80	$ 0.26	$ 0.12	$ 0.59	$ 0.55	$ 2.31	$ 1.53	$ 1.28
Basic weighted average common shares outstanding	29,318,915	29,295,284	29,264,362	29,697,722	30,766,943	31,227,643	31,735,333	31,683,672	29,394,559	31,350,542	32,319,649
Diluted net income per share	$ 0.43	$ 0.26	$ 0.80	$ 0.79	$ 0.26	$ 0.12	$ 0.58	$ 0.55	$ 2.29	$ 1.52	$ 1.27
Diluted weighted average common shares outstanding	29,543,842	29,516,718	29,477,870	29,910,292	30,966,682	31,537,010	32,142,939	32,094,828	29,612,669	31,682,509	32,751,074

Interim Financial Data (Unaudited) - Schedule of Effect on Previously Reported Quarterly Data (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Interim Reporting [Line Items]
Net income	$ 12,629	$ 7,787	$ 23,725	$ 23,706	$ 8,086	$ 3,744	$ 18,715	$ 17,553	$ 67,847	$ 48,098	$ 41,521
Basic net income per share	$ 0.43	$ 0.27	$ 0.81	$ 0.80	$ 0.26	$ 0.12	$ 0.59	$ 0.55	$ 2.31	$ 1.53	$ 1.28
Diluted net income per share	$ 0.43	$ 0.26	$ 0.80	$ 0.79	$ 0.26	$ 0.12	$ 0.58	$ 0.55	$ 2.29	$ 1.52	$ 1.27
Diluted weighted average common shares outstanding	29,543,842	29,516,718	29,477,870	29,910,292	30,966,682	31,537,010	32,142,939	32,094,828	29,612,669	31,682,509	32,751,074
As Reported [Member]
Interim Reporting [Line Items]
Net income		$ 6,898	$ 23,279	$ 23,402
Basic net income per share		$ 0.24	$ 0.80	$ 0.79
Diluted net income per share		$ 0.23	$ 0.79	$ 0.78
Diluted weighted average common shares outstanding		29,457,653	29,423,845	29,860,730

Schedule II - Valuation and Qualifying Accounts and Reserves (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Warranty Reserve [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 33,522	$ 33,841	$ 40,812
Additions (Reductions) Charged to Cost and Expenses	10,852	8,515	3,774
Deductions	(6,682)	(8,834)	(10,745)
Balance at End of Period	37,692	33,522	33,841
Valuation Allowance of Deferred Tax Assets [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	4,582	4,465	4,201
Additions (Reductions) Charged to Cost and Expenses		117	388
Deductions	(521)		(124)
Balance at End of Period	$ 4,061	$ 4,582	$ 4,465

Business and Organization - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016 Segment
Accounting Policies [Abstract]
Number of reportable segments	1