Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accrued Expenses and Other Current Liabilities
Payroll and employee benefits	$ 39,443	$ 50,929
Taxes other than income taxes	56,232	69,061
Interest	2,795	133
Workers' compensation	15,259	16,119
Asset retirement obligations	27,032	10,366
Other	14,495	10,559
Accrued expenses and other current liabilities	$ 155,256	$ 157,167