Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Accrued Liabilities, Current [Abstract]
Accrued salaries, wages and benefits	$ 4,904	$ 4,925
Accrual for self-insurance liabilities	7,848	7,490
Property taxes	1,313	2,146
Sales taxes	681	676
Other accrued expenses	111	566
Total accrued liabilities	$ 14,857	$ 15,803