Supplemental Balance Sheet and Income Statement Information - Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Accrued liabilities
Accrued compensation	$ 64,364	$ 82,462
Deferred revenue and proceeds on insurance and asset sales	71,566	61,473
Other taxes payable	20,170	28,602
Workers' compensation liabilities	7,788	7,788
Interest payable	31,270	62,935
Litigation reserves	13,574	13,976
Dividends declared and payable	3,653	3,653
Other accrued liabilities	9,976	15,196
Accrued liabilities	$ 222,361	$ 276,085