Receivables - Schedule of Receivables (Details) - USD ($) $ in Thousands |
Jun. 28, 2019 |
Dec. 31, 2018 |
|---|---|---|
| Receivables [Abstract] | ||
| Billed receivables | $ 35,321 | $ 44,868 |
| Unbilled receivables (contract assets) | 190,802 | 181,009 |
| Other | 11,124 | 6,242 |
| Total receivables | 237,247 | $ 232,119 |
| Estimate of unbilled contract receivables | $ 5,200 |