Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Payroll and benefits	$ 144,922	$ 117,636
Deferred revenue and customer advances	70,665	65,653
Income taxes payable	44,171	37,961
Accrued settlement costs	37,147	35,304
Accrued interest	23,495	13,046
Accrued severance plan obligations	16,220	14,053
Other accrued expenses	49,039	55,016
Total accrued expenses	$ 385,659	$ 338,669