Description of Business and Summary of Significant Accounting Policies - Additional Information (Details) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
|
Sep. 29, 2017
USD ($)
|
Sep. 30, 2016
USD ($)
|
Sep. 29, 2017
USD ($)
segment
|
Sep. 30, 2016
USD ($)
|
|
| Accounting Policies [Line Items] | ||||
| Number of reportable segments | segment | 1 | |||
| Revenue | $ | $ 269,625 | $ 283,782 | $ 819,005 | $ 902,359 |
| Total revenue | Credit risk | U.S. Army | ||||
| Accounting Policies [Line Items] | ||||
| Concentration risk, percentage | 80.00% | 85.00% | 83.00% | 84.00% |
| High Desert Support Services (HDSS) | ||||
| Accounting Policies [Line Items] | ||||
| Ownership percentage | 40.00% | 40.00% | ||