Supplemental Balance Sheet, Income Statement and Cash Flow Information - Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Accrued liabilities
Accrued compensation	$ 107,876	$ 120,204
Deferred revenue	302,856	340,472
Other taxes payable	22,261	39,850
Workers' compensation liabilities	37,459	37,459
Interest payable	15,629	62,776
Litigation reserves	26,919	27,097
Current liability to discontinued operations	5,543	5,197
Current liability to acquisition of KVS	22,278	22,278
Other accrued liabilities	31,204	31,280
Accrued liabilities	$ 572,025	$ 686,613