Receivables - Schedule of Receivables (Details) - USD ($) $ in Thousands |
Mar. 30, 2018 |
Dec. 31, 2017 |
|---|---|---|
| Receivables [Abstract] | ||
| Billed receivables | $ 87,275 | $ 50,595 |
| Unbilled receivables | 156,048 | 121,601 |
| Other | 2,729 | 2,799 |
| Total receivables | 246,052 | $ 174,995 |
| Estimated unbilled contract receivables related to requests for equitable adjustments and contract line item realignments | $ 3,000 |