Revenue - Revenue by Contract Relationship (Details) - USD ($) $ in Thousands |
3 Months Ended | |
|---|---|---|
Mar. 30, 2018 |
Mar. 31, 2017 |
|
| Disaggregation of Revenue [Line Items] | ||
| Total revenue | $ 320,516 | $ 290,063 |
| Prime contractor | ||
| Disaggregation of Revenue [Line Items] | ||
| Total revenue | 301,028 | 285,033 |
| Subcontractor | ||
| Disaggregation of Revenue [Line Items] | ||
| Total revenue | $ 19,488 | $ 5,030 |