Receivables - Schedule of Receivables (Details) - USD ($) $ in Thousands |
Sep. 30, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Receivables [Abstract] | ||
| Billed receivables | $ 24,648 | $ 53,070 |
| Unbilled contract receivables | 136,358 | 154,658 |
| Other | 3,029 | 2,833 |
| Receivables | $ 164,035 | $ 210,561 |