Revenue Earned in Excess of Billings and Deferred Revenue (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Revenue Earned in Excess of Billings [Line Items]
Revenue earned in excess of billings	$ 25,039	$ 30,448
Time-And-Materials Projects
Revenue Earned in Excess of Billings [Line Items]
Revenue earned in excess of billings	20,828	22,171
Fixed-Price Projects
Revenue Earned in Excess of Billings [Line Items]
Revenue earned in excess of billings	$ 4,211	$ 8,277