Accumulated Other Comprehensive Income (Reclassification Out of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	$ (1,032)	$ 666	$ 854
Other comprehensive income (loss), tax effect	243	(158)	(200)
Other comprehensive income (loss), net of tax	(789)	508	654
Investment securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gains (losses) arising during the period, before tax	(859)	737	968
Net unrealized gains (losses) arising during the period, tax	203	(173)	(227)
Net unrealized gains (losses) arising during the period, net of tax	(656)	564	741
Net realized gains reclassified to income from continuing operations, before tax	102	171	78
Net realized gains reclassified to income from continuing operations, tax	(23)	(39)	(18)
Net realized gains reclassified to income from continuing operations, net of tax	79	132	60
Other comprehensive income (loss), before tax	(961)	566	890
Other comprehensive income (loss), tax effect	226	(134)	(209)
Other comprehensive income (loss), net of tax	(735)	432	681
Cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gains (losses) arising during the period, before tax		169	(11)
Net unrealized gains (losses) arising during the period, tax		(40)	4
Net unrealized gains (losses) arising during the period, net of tax	0	129	(7)
Net realized gains reclassified to income from continuing operations, before tax	61	64	12
Net realized gains reclassified to income from continuing operations, tax	(14)	(15)	(2)
Net realized gains reclassified to income from continuing operations, net of tax	47	49	10
Other comprehensive income (loss), before tax		105	(23)
Other comprehensive income (loss), tax effect		(25)	6
Other comprehensive income (loss), net of tax	(47)	80	(17)
Defined benefit pension plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gains (losses) arising during the period, before tax	(11)
Net unrealized gains (losses) arising during the period, tax	3
Net unrealized gains (losses) arising during the period, net of tax	(8)	(4)	(11)
Net realized gains reclassified to income from continuing operations, before tax	(1)
Net realized gains reclassified to income from continuing operations, tax	0
Net realized gains reclassified to income from continuing operations, net of tax	(1)	0	0
Other comprehensive income (loss), before tax	(10)	(5)	(14)
Other comprehensive income (loss), tax effect	3	1	3
Other comprehensive income (loss), net of tax	(7)	(4)	(11)
Net investment hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax		(4)	(6)
Other comprehensive income (loss), tax effect		1	2
Other comprehensive income (loss), net of tax	0	(3)	(4)
Translation adjustments and net investment hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax		4	7
Other comprehensive income (loss), tax effect		(1)	(2)
Other comprehensive income (loss), net of tax	$ 0	$ 3	$ 5