|
Description of Business and Summary of Significant Accounting Policies - Revenue Recognition (Details) (USD $)
In Thousands, unless otherwise specified
|
3 Months Ended |
12 Months Ended |
|
Dec. 31, 2014
|
Sep. 30, 2014
|
Jun. 30, 2014
|
Mar. 31, 2014
|
Dec. 31, 2013
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Sep. 30, 2013
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Jun. 30, 2013
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Mar. 31, 2013
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Dec. 31, 2014
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Dec. 31, 2013
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Dec. 31, 2012
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| Concentration Risk [Line Items] |
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|
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|
|
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| Operating income |
$ 8,149 |
$ 3,291 |
$ 9,422 |
$ 17,556 |
$ 25,150 |
$ 28,889 |
$ 49,027 |
$ 28,256 |
$ 38,417 |
$ 131,322 |
$ 110,351 |
| Contracts Revenue |
285,765 |
300,651 |
312,902 |
303,951 |
327,074 |
349,211 |
421,041 |
414,312 |
1,203,269 |
1,511,638 |
1,828,364 |
| Contracts Accounted for under Percentage of Completion |
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| Concentration Risk [Line Items] |
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|
|
|
|
|
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|
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| Unfavorable adjustments |
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|
|
|
|
|
|
|
6,629 |
3,906 |
1,065 |
| Sales Revenue, Net | U.S. Army | Government Contracts Concentration Risk |
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| Concentration Risk [Line Items] |
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|
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|
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| Concentration Risk, Percentage |
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|
|
|
|
|
|
|
88.00% |
92.00% |
93.00% |
| Four Largest Contracts | Sales Revenue, Net | U.S. Army | Government Contracts Concentration Risk |
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| Concentration Risk [Line Items] |
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|
|
|
|
|
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| Concentration Risk, Percentage |
|
|
|
|
|
|
|
|
68.00% |
68.60% |
68.20% |
| Contracts Revenue |
|
|
|
|
|
|
|
|
$ 822,000 |
$ 1,037,600 |
$ 1,246,200 |