Revenue - Revenue by Contract Relationship (Details) - USD ($) $ in Thousands |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 28, 2019 |
Jun. 29, 2018 |
Jun. 28, 2019 |
Jun. 29, 2018 |
|
| Disaggregation of Revenue [Line Items] | ||||
| Total revenue | $ 331,589 | $ 321,132 | $ 657,517 | $ 641,649 |
| Prime contractor | ||||
| Disaggregation of Revenue [Line Items] | ||||
| Total revenue | 312,732 | 301,088 | 619,789 | 602,116 |
| Subcontractor | ||||
| Disaggregation of Revenue [Line Items] | ||||
| Total revenue | $ 18,857 | $ 20,044 | $ 37,728 | $ 39,533 |