Accounts Receivable - Summary of Accounts Receivable (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Contract receivables	$ 72,835	$ 86,129
Allowance for doubtful accounts	(1,749)	(1,151)
Accounts receivable, Total	83,062	97,778
Trade Accounts Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade receivables	$ 11,976	$ 12,800