Description of Business and Summary of Significant Accounting Policies - Revenue Recognition (Details) $ in Thousands |
3 Months Ended | 12 Months Ended | |||||||||
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Dec. 31, 2015
USD ($)
|
Sep. 25, 2015
USD ($)
|
Jun. 26, 2015
USD ($)
|
Mar. 27, 2015
USD ($)
|
Dec. 31, 2014
USD ($)
|
Sep. 30, 2014
USD ($)
|
Jun. 30, 2014
USD ($)
|
Mar. 31, 2014
USD ($)
|
Dec. 31, 2015
USD ($)
contract
|
Dec. 31, 2014
USD ($)
|
Dec. 31, 2013
USD ($)
|
|
Concentration Risk [Line Items] | |||||||||||
Number of contracts exceeding threshold | contract | 4 | ||||||||||
Contracts revenue | $ 311,194 | $ 299,061 | $ 309,509 | $ 260,920 | $ 285,765 | $ 300,651 | $ 312,902 | $ 303,951 | $ 1,180,684 | $ 1,203,269 | $ 1,511,638 |
Sales Revenue, Net | U.S. Army | Government Contracts Concentration Risk | |||||||||||
Concentration Risk [Line Items] | |||||||||||
Concentration risk | 85.00% | 88.00% | 92.00% | ||||||||
Four Largest Contracts | Sales Revenue, Net | U.S. Army | Government Contracts Concentration Risk | |||||||||||
Concentration Risk [Line Items] | |||||||||||
Concentration risk | 66.00% | 68.00% | 69.00% | ||||||||
Contracts revenue | $ 775,400 | $ 822,000 | $ 1,000,000 |