Summary of Deferred Revenue (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Deferred Revenue Arrangement [Line Items]
Deferred revenue	$ 3,266	$ 4,729
Fixed-Price Projects
Deferred Revenue Arrangement [Line Items]
Deferred revenue	1,501	3,523
Other Deferred Revenue
Deferred Revenue Arrangement [Line Items]
Deferred revenue	$ 1,765	$ 1,206