Revenue - Revenue by Customer (Details) - USD ($) $ in Thousands |
3 Months Ended | |
|---|---|---|
Mar. 30, 2018 |
Mar. 31, 2017 |
|
| Disaggregation of Revenue [Line Items] | ||
| Total revenue | $ 320,516 | $ 290,063 |
| Army | ||
| Disaggregation of Revenue [Line Items] | ||
| Total revenue | 237,847 | 252,161 |
| Air Force | ||
| Disaggregation of Revenue [Line Items] | ||
| Total revenue | 65,255 | 32,969 |
| Navy | ||
| Disaggregation of Revenue [Line Items] | ||
| Total revenue | 8,357 | 4,933 |
| Other | ||
| Disaggregation of Revenue [Line Items] | ||
| Total revenue | $ 9,057 | $ 0 |