Accounts Receivable - Contract Receivables (Detail) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Accounts Notes And Loans Receivable [Line Items]
Retainages		$ 86,153	$ 58,431
Accounts receivable—trade, net		263,119	334,384
Contract receivables [Member]
Accounts Notes And Loans Receivable [Line Items]
Contracts receivable		171,587	245,604
Unbilled	[1]	4,303	4,303
Less allowances		(17,213)	(14,299)
Accounts receivable—trade, net		263,119	334,384
Contract receivables [Member] | Completed contracts [Member]
Accounts Notes And Loans Receivable [Line Items]
Contracts receivable		$ 18,289	$ 40,345

[1] This amount relates to a project milestone billing for which we are awaiting the customer’s final acceptance certificate. We expect to receive the final acceptance certificate during 2017.