Commitments and Contingencies - Additional Information (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2015 USD ($) ft²	Sep. 30, 2014 USD ($)
Schedule Of Commitments And Contingencies [Line Items]
Charge recorded	$ 206	$ 1,018
Surface Flaking Warranty Reserve [Member]
Schedule Of Commitments And Contingencies [Line Items]
Estimate increase to the warranty reserve	$ 5,426
Percentage change in warranty claims used as a threshold for disclosure	10.00%
Change in warranty reserve for disclosure purposes only	$ 3,200
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
TrexTrim and Trex Reveal Railing [Member] | Residential Use [Member]
Schedule Of Commitments And Contingencies [Line Items]
Warranty period	25 years
TrexTrim and Trex Reveal Railing [Member] | Commercial Use [Member]
Schedule Of Commitments And Contingencies [Line Items]
Warranty period	25 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
Sublease [Member]
Schedule Of Commitments And Contingencies [Line Items]
Lease square feet | ft²	49,756
Net minimum receipts remaining under the Company's existing subleases for 2015	$ 0
Net minimum receipts remaining under the Company's existing subleases for 2016	1,100
Net minimum receipts remaining under the Company's existing subleases for 2017	1,200
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 remaining under the Company's lease relating to its reconsidered corporate relocation for 2015	$ 500
Minimum payments remaining under the Company's lease relating to its reconsidered corporate relocation for 2016	1,900
Minimum payments remaining under the Company's lease relating to its reconsidered corporate relocation for 2017	1,900
Minimum payments remaining under the Company's lease relating to its reconsidered corporate relocation for 2018	2,000
Minimum payments remaining under the Company's lease relating to its reconsidered corporate relocation for 2019	$ 1,000