Description of Business and Summary of Significant Accounting Policies - Additional Information (Details) $ in Thousands |
3 Months Ended | ||
|---|---|---|---|
|
Mar. 30, 2018
USD ($)
segment
|
Mar. 31, 2017
USD ($)
|
Jan. 23, 2018 |
|
| Accounting Policies [Line Items] | |||
| Number of reportable segments | segment | 1 | ||
| Revenue | $ | $ 320,516 | $ 290,063 | |
| Total revenue | Credit risk | U.S. Army | |||
| Accounting Policies [Line Items] | |||
| Concentration risk, percentage | 74.00% | 87.00% | |
| High Desert Support Services (HDSS) | |||
| Accounting Policies [Line Items] | |||
| Ownership percentage | 40.00% | ||
| Sentel Corporation | |||
| Accounting Policies [Line Items] | |||
| Percentage of outstanding common stock acquired | 100.00% | ||