Accounts Receivable and Sales Concentrations - Summary of Accounts Receivables (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Receivables [Abstract]
Trade	$ 140,754	$ 124,226
Less-allowance for doubtful accounts	1,207	1,221	$ 520	$ 445
Accounts receivable, net	$ 139,547	$ 123,005