Strategic Lines of Business and Markets (Business Segment Financial Results) (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net interest income (expense)		$ 469	$ 458	$ 471	$ 513	$ 544	$ 586	$ 603	$ 606	$ 1,911	$ 2,339	$ 2,352
Provision for credit losses		(17)	5	138	411	8	35	44	(13)	537	74	(1)
Noninterest income										1,001	1,010	976
Noninterest expenses		473	446	440	425	451	435	424	433	1,784	1,743	1,794
Provision (benefit) for income taxes		(63)	(48)	(27)	21	(82)	(80)	(87)	(85)	(117)	(334)	(300)
Net Income		$ 215	$ 211	$ 113	$ (65)	$ 269	$ 292	$ 298	$ 339	474	1,198	1,235
Net loan charge-offs (recoveries)										196	107	51
Assets, average										81,146	71,488	70,724
Loans, average										51,631	50,511	48,766
Deposits, average										$ 65,038	$ 55,481	$ 55,935
Return on average assets	[1]									0.58%	1.68%	1.75%
Efficiency ratio	[2]									61.15%	51.82%	53.56%
Commercial Bank
Net interest income (expense)										$ 1,608	$ 1,655	$ 1,613
Provision for credit losses										495	88	6
Noninterest income										555	555	547
Noninterest expenses										826	795	847
Provision (benefit) for income taxes										(182)	(306)	(283)
Net Income										660	1,021	1,024
Net loan charge-offs (recoveries)										192	111	52
Assets, average										45,603	44,946	43,207
Loans, average										44,123	43,477	41,629
Deposits, average										$ 36,603	$ 29,047	$ 30,116
Return on average assets	[1]									1.45%	2.27%	2.37%
Efficiency ratio	[2]									38.19%	35.96%	39.22%
Retail Bank
Net interest income (expense)										$ 502	$ 568	$ 548
Provision for credit losses										7	(4)	(1)
Noninterest income										110	132	136
Noninterest expenses										619	597	602
Provision (benefit) for income taxes										5	(24)	(18)
Net Income										(9)	83	65
Net loan charge-offs (recoveries)										1	1	0
Assets, average										3,281	2,852	2,633
Loans, average										2,468	2,104	2,067
Deposits, average										$ 22,832	$ 20,743	$ 20,812
Return on average assets	[1]									(0.04%)	0.39%	0.31%
Efficiency ratio	[2]									100.48%	84.49%	87.59%
Wealth Management
Net interest income (expense)										$ 167	$ 183	$ 181
Provision for credit losses										35	(14)	(3)
Noninterest income										263	270	266
Noninterest expenses										301	283	293
Provision (benefit) for income taxes										(20)	(44)	(36)
Net Income										74	140	121
Net loan charge-offs (recoveries)										3	(5)	(1)
Assets, average										5,162	5,083	5,214
Loans, average										5,045	4,935	5,081
Deposits, average										$ 4,402	$ 3,833	$ 3,941
Return on average assets	[1]									1.41%	2.76%	2.32%
Efficiency ratio	[2]									70.13%	62.45%	65.60%
Finance
Net interest income (expense)										$ (384)	$ (123)	$ (41)
Provision for credit losses										0	0	0
Noninterest income										55	41	27
Noninterest expenses										2	1	1
Provision (benefit) for income taxes										79	26	14
Net Income										(252)	(57)	(1)
Net loan charge-offs (recoveries)										0	0	0
Assets, average										15,418	13,903	13,548
Loans, average										0	0	0
Deposits, average										1,026	1,673	941
Other
Net interest income (expense)										18	56	51
Provision for credit losses										0	4	(3)
Noninterest income										18	12	0
Noninterest expenses										36	67	51
Provision (benefit) for income taxes										1	14	23
Net Income										1	11	26
Net loan charge-offs (recoveries)										0	0	0
Assets, average										11,682	4,704	6,122
Loans, average										(5)	(5)	(11)
Deposits, average										$ 175	$ 185	$ 125

[1] Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity.

[2] Noninterest expenses as a percentage of the sum of net interest income and noninterest income excluding net gains (losses) from securities and a derivative contract tied to the conversion rate of Visa Class B shares.