Fair Value (Reconciliation of Recurring Fair Value Measurements) (Details) - Fair Value, Recurring - Level 3 - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 7,466	$ 6,987	$ 7,448	$ 7,252
Included in Earnings	(80)	348	235	656
Included in other comprehensive income	24	(22)	13	(22)
Purchases	114	577	334	970
Sales	(105)	(186)	(202)	(627)
Issuances	18	13	41	55
Settlements	(208)	(233)	(629)	(658)
Transfers into Level 3	1	99	4	120
Transfers out of Level 3	(5)	(10)	(19)	(173)
Ending Balance	7,225	7,573	7,225	7,573
Unrealized gains/losses for the period on assets held on Consolidated Balance Sheet	(90)	337	210	613
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	386	384	398	421
Included in Earnings	138	56	242	229
Sales	2	2	4	5
Issuances	3	332	38	445
Settlements	(64)	(409)	(217)	(735)
Ending Balance	465	365	465	365
Unrealized gains/losses for the period on liabilities held on Consolidated Balance Sheet	132	51	263	214
Fair Value Additional Information [Abstract]
Net gains (losses) included in earnings (realized and unrealized) relating to Level 3 assets and liabilities	(218)	292	(7)	427
Net unrealized gains (losses) relating to Level 3 assets and liabilities	(222)	286	(53)	399
Other borrowed funds
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	9	5	9	4
Issuances	2	3	9	9
Settlements	(3)	(1)	(10)	(6)
Ending Balance	8	7	8	7
Financial derivatives
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	183	140	152	123
Included in Earnings	128	50	246	168
Sales	2	2	4	5
Settlements	(32)	(84)	(121)	(188)
Ending Balance	281	108	281	108
Unrealized gains/losses for the period on liabilities held on Consolidated Balance Sheet	129	51	252	173
Other liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	194	239	237	294
Included in Earnings	10	6	(4)	61
Issuances	1	329	29	436
Settlements	(29)	(324)	(86)	(541)
Ending Balance	176	250	176	250
Unrealized gains/losses for the period on liabilities held on Consolidated Balance Sheet	3		11	41
Loans held for sale | Residential mortgage loans held for sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	95	191	103	243
Included in Earnings	1	(3)		(3)
Purchases	2	3	16	12
Sales	(26)	(89)	(37)	(131)
Settlements	(2)	(2)	(6)	(9)
Transfers into Level 3	1	1	4	4
Transfers out of Level 3	(1)	(4)	(10)	(19)
Ending Balance	70	97	70	97
Unrealized gains/losses for the period on assets held on Consolidated Balance Sheet	2	(4)		(3)
Loans held for sale | Commercial mortgage loans held for sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	4	25	11	33
Included in Earnings	1		1
Settlements	(1)		(8)	(8)
Ending Balance	4	25	4	25
Unrealized gains/losses for the period on assets held on Consolidated Balance Sheet
Securities available for sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	877	942	956	1,001
Included in Earnings	4	4	8	13
Included in other comprehensive income	24	(22)	13	(22)
Purchases	1	3	4	6
Sales
Settlements	(25)	(52)	(100)	(126)
Transfers into Level 3		92		95
Ending Balance	881	967	881	967
Unrealized gains/losses for the period on assets held on Consolidated Balance Sheet			(2)
Residential mortgage- backed non-agency
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	624	768	696	819
Included in Earnings	4	5	10	13
Included in other comprehensive income	21	(20)	10	(16)
Settlements	(21)	(40)	(88)	(103)
Ending Balance	628	713	628	713
Commercial mortgage- backed non-agency
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	103	3	103	3
Included in other comprehensive income
Transfers into Level 3		92		92
Ending Balance	103	95	103	95
Asset-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	96	117	102	124
Included in Earnings	1		1	1
Included in other comprehensive income	3	(3)	2	(3)
Settlements	(4)	(11)	(9)	(19)
Ending Balance	96	103	96	103
Other
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	54	54	55	55
Included in Earnings	(1)	(1)	(3)	(1)
Included in other comprehensive income		1	1	(3)
Purchases	1	3	4	6
Settlements		(1)	(3)	(4)
Transfers into Level 3				3
Ending Balance	54	56	54	56
Unrealized gains/losses for the period on assets held on Consolidated Balance Sheet			(2)
Loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	701	745	726	769
Included in Earnings	4	5	12	11
Included in other comprehensive income
Purchases	4	19	16	39
Sales			(2)	(1)
Settlements	(21)	(27)	(59)	(77)
Transfers into Level 3		2		17
Transfers out of Level 3	(4)	(6)	(9)	(20)
Ending Balance	684	738	684	738
Unrealized gains/losses for the period on assets held on Consolidated Balance Sheet	5	5	12	11
Equity investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	2,030	1,623	1,952	1,778
Included in Earnings	27	(9)	53	136
Purchases	85	212	221	444
Sales	(79)	(97)	(163)	(495)
Transfers out of Level 3				(134)
Ending Balance	2,063	1,729	2,063	1,729
Unrealized gains/losses for the period on assets held on Consolidated Balance Sheet	16	(16)	35	103
Mortgage Servicing Rights | Residential mortgage loans held for sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	2,657	2,349	2,654	2,310
Included in Earnings	(71)	215	17	248
Purchases	1	329	30	438
Issuances	6	7	18	17
Settlements	(65)	(63)	(191)	(176)
Ending Balance	2,528	2,837	2,528	2,837
Unrealized gains/losses for the period on assets held on Consolidated Balance Sheet	(71)	215	17	248
Mortgage Servicing Rights | Commercial mortgage loans held for sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	1,082	1,106	1,032	1,113
Included in Earnings	(54)	130	118	238
Purchases	19	10	43	27
Issuances	12	6	23	38
Settlements	(84)	(83)	(241)	(247)
Ending Balance	975	1,169	975	1,169
Unrealized gains/losses for the period on assets held on Consolidated Balance Sheet	(54)	130	118	238
Financial derivatives
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	12	6	6	5
Included in Earnings	8	6	26	13
Purchases	2		4	3
Settlements	(10)	(6)	(24)	(15)
Ending Balance	12	6	12	6
Unrealized gains/losses for the period on assets held on Consolidated Balance Sheet	12	7	30	16
Other assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	8		8
Purchases		1		1
Transfers into Level 3		4		4
Ending Balance	$ 8	$ 5	$ 8	$ 5