Accrued Expenses and Other Current Liabilities and Other Liabilities - Other liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accrued Expenses and Other Current Liabilities and Other Liabilities
Supplemental executive retirement plan obligations	$ 21,503	$ 20,851
Derivative liability	14,388	9,821
Long-term insurance accruals	7,326	7,424
Deferred payroll taxes	5,918
Unrecognized tax benefits	5,465	5,296
Other	1,993	2,412
Total	$ 56,593	$ 45,804