Supplemental Balance Sheet, Income Statement and Cash Flow Information - Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Accrued liabilities
Accrued compensation	$ 100,783	$ 116,775
Deferred revenue	259,671	255,626
Other taxes payable	16,264	16,419
Workers' compensation liabilities	18,255	18,255
Interest payable	25,804	57,233
Litigation reserves	24,026	24,896
Current liability to discontinued operations	5,566	5,462
Dividends declared and payable	17,154	17,039
Other accrued liabilities	29,841	31,543
Accrued liabilities	$ 497,364	$ 543,248