Costs and Estimated Earnings on Uncompleted Contracts - Costs and Estimated Earnings on Uncompleted Contracts Accompanying Consolidated Balance Sheets (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Contractors [Abstract]
Costs and estimated earnings in excess of billings on uncompleted contracts	$ 34,090	$ 23,644
Other current liabilities (Billings in excess of costs and estimated earnings on uncompleted contracts)	(3,300)	(1,120)
Costs in excess of billings on uncompleted contracts or programs	$ 30,790	$ 22,524