Supplemental Balance Sheet, Income Statement and Cash Flow Information - Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Accrued liabilities
Accrued compensation	$ 116,775	$ 120,204
Deferred revenue	255,626	340,472
Other taxes payable	16,419	39,850
Workers' compensation liabilities	18,255	37,459
Interest payable	57,233	62,776
Litigation reserves	24,896	27,097
Current liability to discontinued operations	5,462	5,197
Dividends declared and payable	17,039
Current liability to acquisition of KVS		22,278
Other accrued liabilities	31,543	31,280
Accrued liabilities	$ 543,248	$ 686,613