Accumulated Other Comprehensive Income (Loss) - Components of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Debt securities available for sale and interest-only strips
Net unrealized gains (losses) arising during the period, before tax	$ 38,136	$ 41,399	$ 188,880	$ 90,027
Net unrealized gains (losses) arising during the period, tax effect	(8,947)	(10,077)	(44,554)	(21,913)
Net unrealized gains (losses) arising during the period, net of tax	29,189	31,322	144,326	68,114
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), before tax	1,579	(920)	2,506	(159)
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), tax effect	(371)	223	(588)	38
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), net of tax	1,208	(697)	1,918	(121)
Net unrealized gains (losses) on debt securities available for sale and interest-only strips, before taxes	39,715	40,479	191,386	89,868
Net unrealized gains (losses) on debt securities available for sale and interest-only strips, tax effect	(9,318)	(9,854)	(45,142)	(21,875)
Net unrealized gains (losses) on debt securities available for sale and interest-only strips, net of tax	30,397	30,625	146,244	67,993
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax [Abstract]
Reclassification of amortization of prior service cost to Other non-interest expense, before tax	(11)	(11)	(23)	(23)
Reclassification of amortization of prior service cost to Other non-interest expense, tax effect	2	3	5	7
Reclassification of amortization of prior service cost to Other non-interest expense, net of tax	(9)	(8)	(18)	(16)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax [Abstract]
Foreign currency translation adjustment, before tax	6,407	3,415	(8,019)	6,982
Foreign currency translation adjustment, tax effect	0	0	0	0
Foreign currency translation adjustment, net of tax	6,407	3,415	(8,019)	6,982
Net investment hedges
Net unrealized gains (losses) on net investment hedges, before tax	(5,954)	(2,881)	7,741	(5,931)
Net unrealized gains (losses) on net investment hedges, tax effect	1,397	702	(1,817)	1,444
Net unrealized gains (losses) on net investment hedges, net of tax	(4,557)	(2,179)	5,924	(4,487)
Total other comprehensive income (loss), before tax	40,157	41,002	191,085	90,896
Total other comprehensive income (loss), tax effect	(7,919)	(9,149)	(46,954)	(20,424)
Total other comprehensive income (loss), net of tax	32,238	31,853	144,131	70,472
Total interest income
Debt securities available for sale and interest-only strips
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), before tax	1,625	281	2,379	1,651
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), tax effect	(381)	(69)	(558)	(402)
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), net of tax	1,244	212	1,821	1,249
Gains (losses) on debt securities, net
Debt securities available for sale and interest-only strips
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), before tax	0	(1,066)	0	(1,513)
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), tax effect	0	259	0	368
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), net of tax	0	(807)	0	(1,145)
Other noninterest expense
Debt securities available for sale and interest-only strips
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), before tax	(46)	(135)	127	(297)
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), tax effect	10	33	(30)	72
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), net of tax	$ (36)	$ (102)	$ 97	$ (225)