Supplemental Balance Sheet and Income Statement Information - Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Accrued liabilities
Accrued compensation	$ 66,706	$ 82,462
Deferred revenue and proceeds on insurance and asset sales	63,824	61,473
Other taxes payable	31,870	28,602
Workers' compensation liabilities	7,788	7,788
Interest payable	40,340	62,935
Litigation reserves	14,676	13,976
Dividends declared and payable		3,653
Other accrued liabilities	10,152	15,196
Accrued liabilities	$ 235,356	$ 276,085