Consolidated Statements Of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 91,948	$ 65,626	$ 263,509	$ 188,901
Unrealized (losses) gains on available-for-sale securities
Before tax	(18,149)	811	(63,788)	25,783
Tax effect	4,872	(158)	17,123	(9,968)
Net of tax	(13,277)	653	(46,665)	15,815
Reclassification of net gains on available-for-sale securities included in net income
Before tax	1,001	39	6	31
Tax effect	(271)	(15)	(1)	(12)
Net of tax	730	24	5	19
Reclassification of amortization of unrealized gains and losses on investment securities transferred to held-to-maturity from available-for-sale
Before tax	33	33	49	1,483
Tax effect	(9)	(13)	(13)	(583)
Net of tax	24	20	36	900
Net unrealized (losses) gains on available-for-sale securities	(14,031)	609	(46,706)	14,896
Unrealized gains on derivative instruments
Before tax	212	394	4,369	1,699
Tax effect	(57)	(158)	(1,173)	(669)
Net unrealized gains on derivative instruments	155	236	3,196	1,030
Foreign currency adjustment
Before tax	2,586	5,643	(3,927)	10,678
Tax effect	(644)	(1,437)	976	(2,762)
Net foreign currency adjustment	1,942	4,206	(2,951)	7,916
Total other comprehensive (loss) income	(11,934)	5,051	(46,461)	23,842
Comprehensive income	$ 80,014	$ 70,677	$ 217,048	$ 212,743