Supplemental Balance Sheet, Income Statement and Cash Flow Information - Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Accrued liabilities
Accrued compensation	$ 113,627	$ 116,775
Deferred revenue	278,252	255,626
Other taxes payable	22,001	16,419
Workers' compensation liabilities	18,255	18,255
Interest payable	68,602	57,233
Litigation reserves	22,090	24,896
Current liability to discontinued operations	25,775	5,462
Dividends declared and payable	17,149	17,039
Other accrued liabilities	26,309	31,543
Accrued liabilities	$ 592,060	$ 543,248