Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accrued Liabilities, Current [Abstract]
High deductible insurance	$ 4,980	$ 5,720
Accrued payroll	23,140	16,390
Other	32,420	19,910
Total accrued liabilities	$ 60,540	$ 42,020