Income Taxes (Reconciliation of Provision for Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Federal statutory rate	35.00%	35.00%	35.00%
Expected tax expense at U.S. federal statutory rate of 35%	$ 91,179	$ 49,658	$ 122,279
State income taxes, net of Federal income tax effect	7,261	4,783	13,274
R&D tax credit	(41,144)	(29,363)	(18,655)
Release of tax reserves on previously unrecognized tax benefits	0	(13,438)	(38,612)
Foreign earnings at other than US rates	14,639	5,310	2,959
Other	1,894	2,294	1,325
Provision for income taxes	$ 73,829	$ 19,244	$ 82,570