Description of Business and Summary of Significant Accounting Policies - Additional Information (Details) $ in Thousands |
3 Months Ended | |
|---|---|---|
|
Mar. 31, 2017
USD ($)
segment
|
Apr. 01, 2016
USD ($)
|
|
| Accounting Policies [Line Items] | ||
| Number of reportable segments | segment | 1 | |
| Revenue | $ | $ 290,063 | $ 310,682 |
| Total revenue | Credit risk | U.S. Army | ||
| Accounting Policies [Line Items] | ||
| Concentration risk, percentage | 87.00% | 85.00% |
| High Desert Support Services (HDSS) | ||
| Accounting Policies [Line Items] | ||
| Ownership percentage | 40.00% | |