Accumulated Other Comprehensive Income (Loss) - Components of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Debt securities available for sale and interest-only strips
Net unrealized gains (losses) arising during the period, before tax	$ 150,744	$ 48,628
Net unrealized gains (losses) arising during the period, tax effect	(35,607)	(11,836)
Net unrealized gains (losses) arising during the period, net of tax	115,137	36,792
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), before tax	927	761
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), tax effect	(217)	(185)
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), net of tax	710	576
Net unrealized gains (losses) on debt securities available for sale and interest-only strips, before taxes	151,671	49,389
Net unrealized gains (losses) on debt securities available for sale and interest-only strips, tax effect	(35,824)	(12,021)
Net unrealized gains (losses) on debt securities available for sale and interest-only strips, net of tax	115,847	37,368
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)
Reclassification of amortization of prior service cost to Other non-interest expense, tax effect	3	4
Reclassification of amortization of prior service cost to Other non-interest expense, net of tax	(9)	(8)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax [Abstract]
Foreign currency translation adjustment, before tax	(14,426)	3,567
Foreign currency translation adjustment, tax effect	0	0
Foreign currency translation adjustment, net of tax	(14,426)	3,567
Net investment hedges
Net unrealized gains (losses) on net investment hedges, before tax	13,695	(3,050)
Net unrealized gains (losses) on net investment hedges, tax effect	(3,214)	742
Net unrealized gains (losses) on net investment hedges, net of tax	10,481	(2,308)
Total other comprehensive income (loss), before tax	150,928	49,894
Total other comprehensive income (loss), tax effect	(39,035)	(11,275)
Total other comprehensive income (loss), net of tax	111,893	38,619
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	754	1,370
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), tax effect	(177)	(333)
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), net of tax	577	1,037
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	(447)
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), tax effect	0	109
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), net of tax	0	(338)
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	173	(162)
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), tax effect	(40)	39
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), net of tax	$ 133	$ (123)