Strategic Lines of Business and Markets (Business Segment Financial Results) (Details) - USD ($) $ in Millions		3 Months Ended			6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020		Jun. 30, 2021	Jun. 30, 2020
Net interest income (expense)		$ 465	$ 471		$ 908	$ 984
Provision for credit losses		(135)	138		(317)	549
Noninterest income		284	247		554	484
Noninterest expenses		463	434	[1]	910	851	[1]
Provision (benefit) for income taxes		93	28	[1]	191	9	[1]
Net income		328	118	[1]	678	59	[1]
Net credit-related (recoveries) charge-offs		(11)	50		(8)	134
Assets, average		87,860	81,644		86,218	77,454
Loans, average		49,828	53,498		50,206	51,551
Deposits, average		$ 75,520	$ 64,282		$ 73,467	$ 60,524
Return on average assets	[2]	1.50%	0.58%	[1]	1.59%	0.15%	[1]
Efficiency ratio	[3]	61.66%	60.11%	[1]	62.10%	57.79%	[1]
Commercial Bank
Net interest income (expense)		$ 402	$ 402		$ 784	$ 782
Provision for credit losses		(123)	117		(300)	513
Noninterest income		167	144		326	271
Noninterest expenses		204	203	[1]	419	395	[1]
Provision (benefit) for income taxes		111	47	[1]	224	28	[1]
Net income		377	179	[1]	767	117	[1]
Net credit-related (recoveries) charge-offs		(12)	48		(10)	131
Assets, average		44,283	47,392		44,365	45,823
Loans, average		42,350	45,914		42,625	44,253
Deposits, average		$ 43,682	$ 36,318		$ 42,399	$ 33,274
Return on average assets	[2]	3.21%	1.51%	[1]	3.38%	0.51%	[1]
Efficiency ratio	[3]	35.95%	37.18%	[1]	37.76%	37.55%	[1]
Retail Bank
Net interest income (expense)		$ 145	$ 120		$ 278	$ 245
Provision for credit losses		(7)	5		(1)	8
Noninterest income		30	24		58	52
Noninterest expenses		173	153	[1]	322	298	[1]
Provision (benefit) for income taxes		1	(3)	[1]	1	(2)	[1]
Net income		8	(11)	[1]	14	(7)	[1]
Net credit-related (recoveries) charge-offs		1	1		2	2
Assets, average		3,395	3,306		3,428	3,085
Loans, average		2,533	2,479		2,576	2,277
Deposits, average		$ 25,573	$ 22,647		$ 24,951	$ 21,921
Return on average assets	[2]	0.12%	(0.17%)	[1]	0.11%	(0.05%)	[1]
Efficiency ratio	[3]	98.06%	105.07%	[1]	95.00%	99.39%	[1]
Wealth Management
Net interest income (expense)		$ 43	$ 40		$ 85	$ 81
Provision for credit losses		(4)	16		(16)	28
Noninterest income		71	66		138	136
Noninterest expenses		77	73	[1]	153	143	[1]
Provision (benefit) for income taxes		9	3	[1]	19	9	[1]
Net income		32	14	[1]	67	37	[1]
Net credit-related (recoveries) charge-offs		0	1		0	1
Assets, average		5,063	5,191		5,112	5,134
Loans, average		4,936	5,077		4,998	5,007
Deposits, average		$ 5,103	$ 4,217		$ 4,965	$ 4,120
Return on average assets	[2]	2.40%	1.11%	[1]	2.55%	1.45%	[1]
Efficiency ratio	[3]	66.85%	68.18%	[1]	68.31%	65.36%	[1]
Finance
Net interest income (expense)		$ (127)	$ (95)		$ (244)	$ (139)
Provision for credit losses		0	0		0	0
Noninterest income		9	11		21	25
Noninterest expenses		1	1	[1]	1	1	[1]
Provision (benefit) for income taxes		(26)	(20)	[1]	(51)	(28)	[1]
Net income		(93)	(65)	[1]	(173)	(87)	[1]
Net credit-related (recoveries) charge-offs		0	0		0	0
Assets, average		17,461	14,500		17,212	14,393
Loans, average		0	0		0	0
Deposits, average		944	950		964	1,043
Other
Net interest income (expense)		2	4		5	15
Provision for credit losses		(1)	0		0	0
Noninterest income		7	2		11	0
Noninterest expenses		8	4	[1]	15	14	[1]
Provision (benefit) for income taxes		(2)	1	[1]	(2)	2	[1]
Net income		4	1	[1]	3	(1)	[1]
Net credit-related (recoveries) charge-offs		0	0		0	0
Assets, average		17,658	11,255		16,101	9,019
Loans, average		9	28		7	14
Deposits, average		$ 218	$ 150		$ 188	$ 166

[1] See Defined Benefit Pension and Other Postretirement Costs in Note 1.

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

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