Consolidated Statements Of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 43,831	$ 38,541	$ 82,883	$ 73,041
Unrealized (losses) gains on securities
Before tax	(53,400)	26,049	(27,124)	48,575
Tax effect	20,959	(10,332)	10,628	(19,136)
Net of tax	(32,441)	15,717	(16,496)	29,439
Less: Reclassification of net (losses) gains included in net income
Before tax	(24)	(336)	500	(369)
Tax effect	10	133	(196)	146
Net of tax	(14)	(203)	304	(223)
Net unrealized (losses) gains on securities	(32,427)	15,920	(16,800)	29,662
Unrealized gains (losses) on derivative instruments
Before tax	215	(626)	(346)	(724)
Tax effect	(84)	249	136	288
Net unrealized gains (losses) on derivative instruments	131	(377)	(210)	(436)
Foreign currency translation adjustment
Before tax	2,072	9,045	(10,218)	(914)
Tax effect	(556)	(2,338)	2,689	221
Net foreign currency translation adjustment	1,516	6,707	(7,529)	(693)
Total other comprehensive (loss) income	(30,780)	22,250	(24,539)	28,533
Comprehensive income	$ 13,051	$ 60,791	$ 58,344	$ 101,574