Description of Business and Summary of Significant Accounting Policies - Summary of Cumulative Catch-Up Adjustments (Details) (Contracts Accounted for under Percentage of Completion, USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Concentration Risk [Line Items]      
Favorable adjustments $ 3,981 $ 42,206 $ 11,896
Unfavorable adjustments (6,629) (3,906) (1,065)
Net (unfavorable) favorable adjustments (2,648) 38,300 10,831
Tethered Aerostat Radar System      
Concentration Risk [Line Items]      
Unfavorable adjustments $ (2,500)