Significant Accounting Policies (Policies)	9 Months Ended
Sep. 30, 2017
Accounting Policies [Abstract]
Revenue Recognition	Revenue Recognition For Trex Commercial Products, the Company recognizes revenue using the percentage of completion method measured by the ratio of direct costs incurred to date to estimated total costs for each contract. Contract costs include all direct material, labor, subcontract and certain indirect costs. Administrative costs are charged to expense as incurred. Provisions for estimated losses on uncompleted contracts are recognized when such losses are determined. Changes in job performance, conditions and estimated profitability may result in revisions to costs and income and are recognized in the period they are determined. Revenues recognized in excess of amounts billed are classified under current assets. Billings in excess of revenues are classified under current liabilities.
Concentrations and Credit Risk	Concentrations and Credit Risk In addition to its trade receivables, the Company assesses the credit risk exposure of its customers’ contracts receivable by considering the length of time receivables may be past due, the customer’s financial condition and ability to repay the obligation, historical and expected credit loss experience, and other factors. Contracts receivable are carried at the original invoice amount in accounts receivable in the Company’s Condensed Consolidated Balance Sheet and are generally due when billed, and contract retainage is generally due at the completion of the construction contract.
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 September 30, 2017 and December 31, 2016.
Share-based Compensation	The Company has one stock-based compensation plan, the 2014 Stock Incentive Plan (Plan), approved by the Company’s stockholders in April 2014. The Plan amended and restated in its entirety the Trex Company, Inc. 2005 Stock Incentive Plan. 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. As of September 30, 2017, the total aggregate number of shares of the Company’s common stock that may be issued under the Plan is 6,420,000.

Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2017

Revenue Recognition

For Trex Commercial Products, the Company recognizes revenue using the percentage of completion method measured by the ratio of direct costs incurred to date to estimated total costs for each contract. Contract costs include all direct material, labor, subcontract and certain indirect costs. Administrative costs are charged to expense as incurred. Provisions for estimated losses on uncompleted contracts are recognized when such losses are determined. Changes in job performance, conditions and estimated profitability may result in revisions to costs and income and are recognized in the period they are determined. Revenues recognized in excess of amounts billed are classified under current assets. Billings in excess of revenues are classified under current liabilities.

Concentrations and Credit Risk

Concentrations and Credit Risk

In addition to its trade receivables, the Company assesses the credit risk exposure of its customers’ contracts receivable by considering the length of time receivables may be past due, the customer’s financial condition and ability to repay the obligation, historical and expected credit loss experience, and other factors. Contracts receivable are carried at the original invoice amount in accounts receivable in the Company’s Condensed Consolidated Balance Sheet and are generally due when billed, and contract retainage is generally due at the completion of the construction contract.

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 September 30, 2017 and December 31, 2016.

Share-based Compensation

The Company has one stock-based compensation plan, the 2014 Stock Incentive Plan (Plan), approved by the Company’s stockholders in April 2014. The Plan amended and restated in its entirety the Trex Company, Inc. 2005 Stock Incentive Plan. 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. As of September 30, 2017, the total aggregate number of shares of the Company’s common stock that may be issued under the Plan is 6,420,000.