Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Accrued Expenses and Other Current Liabilities
Payroll and employee benefits	$ 44,220	$ 50,929
Taxes other than income taxes	63,503	69,061
Interest	127	133
Workers' compensation	14,412	16,119
Asset retirement obligations	10,366	10,366
Other	10,426	10,559
Accrued expenses and other current liabilities	$ 143,054	$ 157,167