Consolidated Statements Of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 89,580	$ 64,897	$ 171,561	$ 123,275
Unrealized (losses) gains on available-for-sale securities
Before tax	(9,455)	17,593	(45,639)	24,972
Tax effect	2,541	(6,910)	12,251	(9,810)
Net of tax	(6,914)	10,683	(33,388)	15,162
Reclassification of net gains (losses) on available-for-sale securities included in net income
Before tax	(20)	47	(995)	(8)
Tax effect	8	(18)	270	3
Net of tax	(12)	29	(725)	(5)
Reclassification of amortization of unrealized gains and losses on investment securities transferred to held-to-maturity from available-for-sale
Before tax	20	22	16	1,450
Tax effect	(5)	(9)	(4)	(570)
Net of tax	15	13	12	880
Net unrealized (losses) gains on available-for-sale securities	(6,917)	10,641	(32,675)	14,287
Unrealized gains (losses) on derivative instruments
Before tax	1,082	(310)	4,157	1,305
Tax effect	(290)	123	(1,116)	(511)
Net unrealized gains (losses) on derivative instruments	792	(187)	3,041	794
Foreign currency adjustment
Before tax	(2,660)	3,820	(6,513)	5,035
Tax effect	664	(987)	1,620	(1,325)
Net foreign currency adjustment	(1,996)	2,833	(4,893)	3,710
Total other comprehensive (loss) income	(8,121)	13,287	(34,527)	18,791
Comprehensive income	$ 81,459	$ 78,184	$ 137,034	$ 142,066