Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Accrued Liabilities, Current [Abstract]
High deductible insurance	$ 6,250	$ 6,580
Accrued payroll	16,060	20,220
Other	24,880	23,680
Total accrued liabilities	$ 47,190	$ 50,480