Supplemental Balance Sheet, Income Statement and Cash Flow Information (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Accrued liabilities
Accrued compensation	$ 120,204	$ 177,707
Deferred revenue	340,472	298,345
Other taxes payable	43,838	58,445
Workers' compensation liabilities	37,459	37,459
Interest payable	62,776	63,532
Litigation reserves	27,097	23,681
Current liability to discontinued operations	5,197	19,602
Current deferred tax liability		3,677
Current liability to acquisition of KVS	22,278	22,278
Other accrued liabilities	27,292	23,278
Accrued liabilities	$ 686,613	$ 728,004