Annual report pursuant to Section 13 and 15(d)

Contract Costs - Additional Information (Detail)

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Contract Costs - Additional Information (Detail) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Long-term Contracts or Programs Disclosure [Line Items]      
Percentage of pass-through costs included in revenue 48.30% 45.30% 36.10%
Prepaid subcontractor costs $ 33,145 $ 9,731