Additional Information (Details) - USD ($) $ in Thousands |
3 Months Ended | ||
|---|---|---|---|
Mar. 31, 2018 |
Mar. 31, 2017 |
Dec. 31, 2017 |
|
| Supplemental Cash Flow Elements [Abstract] | |||
| Income tax payments | $ 0 | $ 3,100 | |
| Interest payments on debt | 6,875 | 6,875 | |
| Interest payments on capital leases | 15 | $ 21 | |
| Negative cash book balances | $ 49,200 | $ 49,700 | |