Revenue - Revenue by Contract Relationship (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 27, 2019 |
Sep. 28, 2018 |
Sep. 27, 2019 |
Sep. 28, 2018 |
|
| Disaggregation of Revenue [Line Items] | ||||
| Total revenue | $ 359,854 | $ 308,095 | $ 1,017,371 | $ 949,744 |
| Prime contractor | ||||
| Disaggregation of Revenue [Line Items] | ||||
| Total revenue | 334,383 | 290,090 | 954,172 | 892,206 |
| Subcontractor | ||||
| Disaggregation of Revenue [Line Items] | ||||
| Total revenue | $ 25,471 | $ 18,005 | $ 63,199 | $ 57,538 |