Description of Business and Summary of Significant Accounting Policies - Additional Information (Details) $ in Thousands |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
|
Jun. 30, 2017
USD ($)
|
Jul. 01, 2016
USD ($)
|
Jun. 30, 2017
USD ($)
segment
|
Jul. 01, 2016
USD ($)
|
|
| Accounting Policies [Line Items] | ||||
| Number of reportable segments | segment | 1 | |||
| Revenue | $ | $ 259,318 | $ 307,895 | $ 549,380 | $ 618,577 |
| Total revenue | Credit risk | U.S. Army | ||||
| Accounting Policies [Line Items] | ||||
| Concentration risk, percentage | 85.00% | 84.00% | ||
| High Desert Support Services (HDSS) | ||||
| Accounting Policies [Line Items] | ||||
| Ownership percentage | 40.00% | 40.00% | ||