Accumulated Other Comprehensive Income (Schedule of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 14,625	$ 13,519	$ 14,703	$ 14,416
Net change	189	109	(415)	692
Ending balance	17,530	13,826	17,530	13,826
Accumulated other comprehensive income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	27	706	631	123
Ending balance	216	815	216	815
Unrealized gains on investment securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	53	661	640	208
Net change	206	122	(381)	575
Ending balance	259	783	259	783
Translation adjustments and net investment hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	20	18	19	19
Net change	0	1	1	0
Ending balance	20	19	20	19
Cash flow hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	65	130	82	2
Net change	(17)	(14)	(34)	114
Ending balance	48	116	48	116
Defined benefit pension plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(111)	(103)	(110)	(106)
Net change	0	0	(1)	3
Ending balance	$ (111)	$ (103)	$ (111)	$ (103)