Accumulated Other Comprehensive Loss (Reclassification Out of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	$ (1,184)	$ (1,743)	$ (928)	$ (5,482)
Other comprehensive income (loss), tax effect	282	412	222	1,300
Other comprehensive (loss) income, net of tax	(902)	(1,331)	(706)	(4,182)
Investment securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gains (losses) arising during the period, before tax		(1,757)	(877)	(5,465)
Net unrealized gains (losses) arising during the period, tax		416	209	1,295
Net unrealized gains (losses) arising during the period, net of tax		(1,341)	(668)	(4,170)
Net realized gains reclassified to income from continuing operations, before tax		2	5	23
Net realized gains reclassified to income from continuing operations, tax		0	(1)	(5)
Net realized gains reclassified to income from continuing operations, net of tax		2	4	18
Other comprehensive income (loss), before tax	(1,163)	(1,759)	(882)	(5,488)
Other comprehensive income (loss), tax effect	277	416	210	1,300
Other comprehensive (loss) income, net of tax	(886)	(1,343)	(672)	(4,188)
Translation adjustments and net investment hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	(5)	(11)	1	(13)
Other comprehensive income (loss), tax effect	1	2	0	3
Other comprehensive (loss) income, net of tax	(4)	(9)	1	(10)
Net investment hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	4	10	1	11
Other comprehensive income (loss), tax effect	(1)	(2)	0	(2)
Other comprehensive (loss) income, net of tax	3	8	1	9
Cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gains (losses) arising during the period, before tax	(15)		(33)
Net unrealized gains (losses) arising during the period, tax	4		9
Net unrealized gains (losses) arising during the period, net of tax	(11)		(24)
Net realized gains reclassified to income from continuing operations, before tax	5	4	15	15
Net realized gains reclassified to income from continuing operations, tax	(1)	(1)	(3)	(4)
Net realized gains reclassified to income from continuing operations, net of tax	4	3	12	11
Other comprehensive income (loss), before tax	(20)		(48)
Other comprehensive income (loss), tax effect	5		12
Other comprehensive (loss) income, net of tax	$ (15)		$ (36)
Defined benefit pension plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gains (losses) arising during the period, before tax				2
Net unrealized gains (losses) arising during the period, tax				0
Net unrealized gains (losses) arising during the period, net of tax				2
Net realized gains reclassified to income from continuing operations, before tax		(21)		(21)
Net realized gains reclassified to income from continuing operations, tax		5		5
Net realized gains reclassified to income from continuing operations, net of tax		$ (16)		(16)
Other comprehensive income (loss), before tax				23
Other comprehensive income (loss), tax effect				(5)
Other comprehensive (loss) income, net of tax				$ 18