Supplemental Balance Sheet and Income Statement Information - Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Accrued liabilities
Accrued compensation	$ 76,640	$ 97,003
Deferred revenue and proceeds on insurance and asset sales	69,089	89,051
Other taxes payable	19,872	31,472
Workers' compensation liabilities	15,214	30,214
Interest payable	61,003	51,316
Litigation reserves	14,493	14,736
Dividends declared and payable	3,653	7,832
Other accrued liabilities	14,306	11,658
Accrued liabilities	$ 274,270	$ 333,282