Accrued Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Payables and Accruals [Abstract]
Payroll and benefits	$ 121,421	$ 95,011
Deferred revenue and customer advances	55,916	49,243
Accrued settlement costs	34,127	32,987
Income taxes payable	21,899	21,448
Accrued severance plan obligations	14,979	14,306
Accrued interest	13,054	12,920
Other accrued expenses	39,362	38,297
Total accrued expenses	$ 300,758	$ 264,212