Accumulated Other Comprehensive Income (Loss) - Components of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Debt securities available for sale and interest-only strips
Net unrealized gains (losses) arising during the period, before tax	$ (8,489)	$ 24,236	$ 180,391	$ 114,263
Net unrealized gains (losses) arising during the period, tax effect	1,992	(5,606)	(42,562)	(27,519)
Net unrealized gains (losses) arising during the period, net of tax	(6,497)	18,630	137,829	86,744
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), before tax	(1,564)	791	942	632
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), tax effect	367	(191)	(221)	(153)
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), net of tax	(1,197)	600	721	479
Net unrealized gains (losses) on debt securities available for sale and interest-only strips, before taxes	(10,053)	25,027	181,333	114,895
Net unrealized gains (losses) on debt securities available for sale and interest-only strips, tax effect	2,359	(5,797)	(42,783)	(27,672)
Net unrealized gains (losses) on debt securities available for sale and interest-only strips, net of tax	(7,694)	19,230	138,550	87,223
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	(12)	(12)	(35)	(35)
Reclassification of amortization of prior service cost to Other non-interest expense, tax effect	3	3	8	10
Reclassification of amortization of prior service cost to Other non-interest expense, net of tax	(9)	(9)	(27)	(25)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax [Abstract]
Foreign currency translation adjustment, before tax	3,721	(1,968)	(4,298)	5,014
Foreign currency translation adjustment, tax effect	0	0	0	0
Foreign currency translation adjustment, net of tax	3,721	(1,968)	(4,298)	5,014
Net investment hedges
Net unrealized gains (losses) on net investment hedges, before tax	(3,469)	2,170	4,272	(3,761)
Net unrealized gains (losses) on net investment hedges, tax effect	814	(529)	(1,003)	915
Net unrealized gains (losses) on net investment hedges, net of tax	(2,655)	1,641	3,269	(2,846)
Total other comprehensive income (loss), before tax	(9,813)	25,217	181,272	116,113
Total other comprehensive income (loss), tax effect	3,176	(6,323)	(43,778)	(26,747)
Total other comprehensive income (loss), net of tax	(6,637)	18,894	137,494	89,366
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	777	844	3,156	2,495
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), tax effect	(183)	(205)	(741)	(607)
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), net of tax	594	639	2,415	1,888
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	(2,309)	0	(2,309)	(1,513)
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), tax effect	542	0	542	368
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), net of tax	(1,767)	0	(1,767)	(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	(32)	(53)	95	(350)
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), tax effect	8	14	(22)	86
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), net of tax	$ (24)	$ (39)	$ 73	$ (264)