Accumulated Other Comprehensive Loss (Reclassification Out of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	$ (226)	$ 371
Other comprehensive income (loss), tax effect	53	(88)
Other comprehensive income (loss), net of tax	(173)	283
Available-for-sale securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gains (losses) arising during the period, before tax	(223)	377
Net unrealized gains (losses) arising during the period, tax	53	(89)
Net unrealized gains (losses) arising during the period, net of tax	(170)	288
Reclassification from AOCI, before tax	1	5
Reclassification from AOCI, tax	0	(1)
Reclassification from AOCI, net of tax	1	4
Other comprehensive income (loss), before tax	(224)	372
Other comprehensive income (loss), tax effect	53	(88)
Other comprehensive income (loss), net of tax	(171)	284
Held-to-maturity securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI, before tax	(20)
Reclassification from AOCI, tax	5
Reclassification from AOCI, net of tax	(15)
Translation adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	(5)
Other comprehensive income (loss), tax effect	1
Other comprehensive income (loss), net of tax	(4)
Net investment hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	4
Other comprehensive income (loss), tax effect	(1)
Other comprehensive income (loss), net of tax	3
Cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gains (losses) arising during the period, before tax	(22)	4
Net unrealized gains (losses) arising during the period, tax	5	(1)
Net unrealized gains (losses) arising during the period, net of tax	(17)	3
Reclassification from AOCI, before tax	(1)	5
Reclassification from AOCI, tax	0	(1)
Reclassification from AOCI, net of tax	(1)	4
Other comprehensive income (loss), before tax	(21)	(1)
Other comprehensive income (loss), tax effect	5	0
Other comprehensive income (loss), net of tax	$ (16)	$ (1)