Acquisition - Additional Information (Detail) - USD ($)			3 Months Ended								5 Months Ended	12 Months Ended
	Aug. 17, 2017	Jul. 31, 2017	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Repayment of revolving credit facility												$ 172,250,000	$ 201,000,000	$ 249,700,000
Goodwill			$ 68,500,000									68,500,000
Net income (loss)			25,171,000	$ 29,471,000	$ 42,820,000	$ 37,110,000	$ 18,299,000	$ 20,098,000	$ 28,782,000	$ 27,949,000		134,572,000	95,128,000	$ 67,847,000
Amortization expense												3,100,000	2,000,000
Acquisition-related expenses											$ 500,000
Trex Commercial Products, Inc. (TCP) [Member]
Business Acquisition [Line Items]
Net sales											21,800,000	71,000,000
Net income (loss)											(2,300)	2,700,000
Amortization expense											2,000,000	2,900,000
Staging Concepts Acquisition, LLC [Member]
Business Acquisition [Line Items]
Certain assets and liabilities acquired		$ 71,800,000
Total consideration		71,804,000
Goodwill		57,938,000
Goodwill expected to be amortized and deductible for tax purposes			$ 3,900,000				$ 1,600,000				$ 1,600,000	$ 3,900,000	$ 1,600,000
Amortization period for intangible assets												12 months
Staging Concepts Acquisition, LLC [Member] | Revolving Credit Facility [Member]
Business Acquisition [Line Items]
Fund used to acquire business from revolving credit facility		$ 30,000,000
Repayment of revolving credit facility	$ 30,000,000