Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accrued Liabilities, Current [Abstract]
High deductible insurance	$ 5,720	$ 6,080
Accrued payroll	16,390	17,950
Other	19,910	19,860
Total accrued liabilities	$ 42,020	$ 43,890