Supplemental Balance Sheet and Income Statement Information - Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Accrued liabilities
Accrued compensation	$ 71,278	$ 82,462
Deferred revenue and proceeds on insurance and asset sales	69,654	61,473
Other taxes payable	29,027	28,602
Workers' compensation liabilities	7,788	7,788
Interest payable	70,245	62,935
Litigation reserves	14,621	13,976
Dividends declared and payable		3,653
Other accrued liabilities	8,277	15,196
Accrued liabilities	$ 270,890	$ 276,085