Consolidated Statements Of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 81,981	$ 58,378
Unrealized (losses) gains on available-for-sale securities
Before tax	(36,184)	7,379
Tax effect	9,710	(2,900)
Net of tax	(26,474)	4,479
Reclassification of net losses on available-for-sale securities included in net income
Before tax	(975)	(55)
Tax effect	262	21
Net of tax	(713)	(34)
Reclassification of amortization of unrealized gains and losses on investment securities transferred to held-to-maturity from available-for-sale
Before tax	(4)	1,428
Tax effect	1	(561)
Net of tax	(3)	867
Net unrealized (losses) gains on available-for-sale securities	(25,758)	3,646
Unrealized gains on derivative instruments
Before tax	3,075	1,615
Tax effect	(826)	(634)
Net unrealized gains on derivative instruments	2,249	981
Foreign currency adjustment
Before tax	(3,853)	1,215
Tax effect	956	(338)
Net foreign currency adjustment	(2,897)	877
Total other comprehensive (loss) income	(26,406)	5,504
Comprehensive income	$ 55,575	$ 63,882