Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accrued Liabilities, Current [Abstract]
Accrued salaries, wages and benefits	$ 6,492	$ 9,632
Accrual for insurance liabilities	5,680	5,233
Property taxes	924	513
Capital lease liability	3,045	0
Sales taxes	2,178	1,836
Interest	0	46
Other accrued expenses	521	613
Total accrued liabilities	$ 18,840	$ 17,873