Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Accrued Liabilities
Salaries, wages, and commissions	$ 30,897	$ 32,154
Insurance liabilities	23,245	22,506
Deferred revenue	15,533	16,139
Interest payable on long-term debt	9,588	3,966
Other	28,064	23,653
Total accrued liabilities	$ 107,327	$ 98,418