Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Accrued Liabilities
Salaries, wages, and commissions	$ 25,773	$ 20,684
Insurance liabilities	21,777	20,410
Other	33,649	23,305
Total Accrued Liabilities	$ 81,199	$ 64,399