Accounts Receivable and Sales Concentrations - Summary of Accounts Receivables (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Receivables [Abstract]
Trade	$ 123,689	$ 98,030
Less - allowance for doubtful accounts	684	520	$ 445	$ 311
Accounts receivable, net	$ 123,005	$ 97,510