Income Taxes (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Difference between the income tax computation by the company and the statutory body
Provision at the U.S. federal statutory rate	$ 63,760	$ 57,540	$ 67,163
Increase (decrease) resulting from:
State income tax, net of benefit for federal deduction	4,448	5,267	4,228
Foreign income tax rate differential	(2,002)	(3,188)	(538)
Employment credits	(407)	(481)	(421)
Changes in valuation allowances	14,667	9,507	2,713
Nondeductible Goodwill	4,651	0	1,355
Income Tax Reconciliation Goodwill created from Restructuring	0	(10,209)	0
Nondeductible Transaction Costs	0	0	1,064
Stock-based compensation	386	245	282
Income tax reconciliation convertible debt redemption	0	9,727	0
Other	2,669	2,988	2,057
Provision for income taxes	$ 88,172	$ 71,396	$ 77,903