Accumulated Other Comprehensive Income (Loss) - Components of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Debt securities available for sale and interest-only strips
Net unrealized gains (losses) arising during the period, before tax	$ (237,054)	$ 150,744
Net unrealized gains (losses) arising during the period, tax effect	56,371	(35,607)
Net unrealized gains (losses) arising during the period, net of tax	(180,683)	115,137
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), before tax	93	927
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), tax effect	(22)	(217)
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), net of tax	71	710
Net unrealized gains (losses) on debt securities available for sale and interest-only strips, before taxes	(236,961)	151,671
Net unrealized gains (losses) on debt securities available for sale and interest-only strips, tax effect	56,349	(35,824)
Net unrealized gains (losses) on debt securities available for sale and interest-only strips, net of tax	(180,612)	115,847
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	(23)	(12)
Reclassification of amortization of prior service cost to Other non-interest expense, tax effect	5	3
Reclassification of amortization of prior service cost to Other non-interest expense, net of tax	(18)	(9)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax [Abstract]
Foreign currency translation adjustment, before tax	2,170	(14,426)
Foreign currency translation adjustment, tax effect	0	0
Foreign currency translation adjustment, net of tax	2,170	(14,426)
Net investment hedges
Net unrealized gains (losses) on net investment hedges, before tax	(2,046)	13,695
Net unrealized gains (losses) on net investment hedges, tax effect	487	(3,214)
Net unrealized gains (losses) on net investment hedges, net of tax	(1,559)	10,481
Total other comprehensive income (loss), before tax	(236,860)	150,928
Total other comprehensive income (loss), tax effect	56,841	(39,035)
Total other comprehensive income (loss), net of tax	(180,019)	111,893
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	(44)	754
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), tax effect	10	(177)
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), net of tax	(34)	577
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	0
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), tax effect	0	0
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), net of tax	0	0
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	137	173
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), tax effect	(32)	(40)
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), net of tax	$ 105	$ 133