Accumulated Other Comprehensive Income (Schedule of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 17,530	$ 13,826	$ 14,703	$ 14,416
Net change	(165)	(120)	(580)	572
Ending balance	17,289	14,126	17,289	14,126
Accumulated other comprehensive income (loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	216	815	631	123
Ending balance	51	695	51	695
Unrealized gains on investment securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	259	783	640	208
Net change	(157)	(103)	(538)	472
Ending balance	102	680	102	680
Translation adjustments and net investment hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	20	19	19	19
Net change	0	(1)	1	(1)
Ending balance	20	18	20	18
Cash flow hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	48	116	82	2
Net change	(9)	(16)	(43)	98
Ending balance	39	100	39	100
Defined benefit pension plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(111)	(103)	(110)	(106)
Net change	1	0	0	3
Ending balance	$ (110)	$ (103)	$ (110)	$ (103)