Investment in Joint Venture - Summarized Income Statement Information of Unconsolidated Joint Venture (Detail) - Joint Venture [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Schedule of Equity Method Investments [Line Items]
Net sales	$ 18,111	$ 17,473	$ 36,114	$ 36,584
Cost of sales	15,537	13,724	30,684	28,160
Income from operations	2,157	3,385	4,665	7,796
Net income	$ 1,552	$ 2,770	$ 3,504	$ 6,459