Loans and Related Allowance for Credit Losses (Modified, Amortized Cost Basis) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 1,326	$ 869	$ 2,233	$ 1,275
% of Loan Class	0.41%	0.27%	0.69%	0.40%
Unfunded lending related commitments	$ 300	$ 100	$ 300	$ 100
Principal Forgiveness
Financing Receivable [Line Items]
Amortized cost basis, modified				1
Interest Rate Reduction
Financing Receivable [Line Items]
Amortized cost basis, modified	18	1	18	1
Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	827	595	1,502	927
Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	129	97	171	148
Repayment Plan
Financing Receivable [Line Items]
Amortized cost basis, modified	22	21	42	36
Payment Delay and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	149		257
Interest Rate Reduction and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	103	1	113	2
Interest Rate Reduction and Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified			15
Other
Financing Receivable [Line Items]
Amortized cost basis, modified	78	154	115	160
Commercial and industrial | Principal Forgiveness
Financing Receivable [Line Items]
Amortized cost basis, modified				1
Commercial and industrial | Interest Rate Reduction
Financing Receivable [Line Items]
Amortized cost basis, modified	120		145
Commercial and industrial | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	539	366	941	432
Commercial and industrial | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	159	59	207	72
Commercial real estate | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	538	228	927	493
Commercial real estate | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	84		173
Residential real estate | Interest Rate Reduction
Financing Receivable [Line Items]
Amortized cost basis, modified	1	2	1	3
Residential real estate | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	1	1	1	2
Residential real estate | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	30	35	55	72
Home equity | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	5	3	8	4
Education | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	1	1	3	2
Total commercial
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 1,256	$ 800	$ 2,106	$ 1,149
% of Loan Class	0.57%	0.36%	0.95%	0.52%
Total commercial | Principal Forgiveness
Financing Receivable [Line Items]
Amortized cost basis, modified				$ 1
Total commercial | Interest Rate Reduction
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 18		$ 18
Total commercial | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	826	$ 594	1,499	925
Total commercial | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	94	59	108	72
Total commercial | Payment Delay and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	149		257
Total commercial | Interest Rate Reduction and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	102		112
Total commercial | Interest Rate Reduction and Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified			15
Total commercial | Other
Financing Receivable [Line Items]
Amortized cost basis, modified	67	147	97	151
Total commercial | Commercial and industrial
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 718	$ 512	$ 1,154	$ 596
% of Loan Class	0.40%	0.29%	0.65%	0.34%
Total commercial | Commercial and industrial | Principal Forgiveness
Financing Receivable [Line Items]
Amortized cost basis, modified				$ 1
Total commercial | Commercial and industrial | Interest Rate Reduction
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 18		$ 18
Total commercial | Commercial and industrial | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	372	$ 366	720	432
Total commercial | Commercial and industrial | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	94	59		72
Total commercial | Commercial and industrial | Payment Deferral, Adjustment
Financing Receivable [Line Items]
Amortized cost basis, modified			83
Total commercial | Commercial and industrial | Payment Delay and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	65		109
Total commercial | Commercial and industrial | Interest Rate Reduction and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	102		112
Total commercial | Commercial and industrial | Interest Rate Reduction and Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified			15
Total commercial | Commercial and industrial | Other
Financing Receivable [Line Items]
Amortized cost basis, modified	67	87	97	91
Total commercial | Commercial real estate
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 538	$ 288	$ 952	$ 553
% of Loan Class	1.52%	0.80%	2.68%	1.54%
Total commercial | Commercial real estate | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 454	$ 228	$ 779	$ 493
Total commercial | Commercial real estate | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified			25
Total commercial | Commercial real estate | Payment Delay and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	84		148
Total commercial | Commercial real estate | Other
Financing Receivable [Line Items]
Amortized cost basis, modified		60		60
Total consumer
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 70	$ 69	$ 127	$ 126
% of Loan Class	0.07%	0.07%	0.13%	0.12%
Total consumer | Interest Rate Reduction
Financing Receivable [Line Items]
Amortized cost basis, modified		$ 1		$ 1
Total consumer | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 1	1	$ 3	2
Total consumer | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	35	38	63	76
Total consumer | Repayment Plan
Financing Receivable [Line Items]
Amortized cost basis, modified	22	21	42	36
Total consumer | Interest Rate Reduction and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	1	1	1	2
Total consumer | Other
Financing Receivable [Line Items]
Amortized cost basis, modified	11	7	18	9
Total consumer | Residential real estate
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 36	$ 39	$ 64	$ 78
% of Loan Class	0.08%	0.08%	0.14%	0.17%
Total consumer | Residential real estate | Interest Rate Reduction
Financing Receivable [Line Items]
Amortized cost basis, modified		$ 1		$ 1
Total consumer | Residential real estate | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 30	35	$ 55	72
Total consumer | Residential real estate | Interest Rate Reduction and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	1	1	1	2
Total consumer | Residential real estate | Other
Financing Receivable [Line Items]
Amortized cost basis, modified	5	2	8	3
Total consumer | Home equity
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 12	$ 10	$ 20	$ 15
% of Loan Class	0.05%	0.04%	0.08%	0.06%
Total consumer | Home equity | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 5	$ 3	$ 8	$ 4
Total consumer | Home equity | Repayment Plan
Financing Receivable [Line Items]
Amortized cost basis, modified	1	2	2	5
Total consumer | Home equity | Interest Rate Reduction and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified
Total consumer | Home equity | Other
Financing Receivable [Line Items]
Amortized cost basis, modified	6	5	10	6
Total consumer | Credit card
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 21	$ 18	$ 39	$ 30
% of Loan Class	0.31%	0.25%	0.57%	0.42%
Total consumer | Credit card | Repayment Plan
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 21	$ 18	$ 39	$ 30
Total consumer | Education
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 1	$ 1	$ 3	$ 2
% of Loan Class	0.06%	0.05%	0.17%	0.10%
Total consumer | Education | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 1	$ 1	$ 3	$ 2
Total consumer | Other consumer
Financing Receivable [Line Items]
Amortized cost basis, modified		$ 1	$ 1	$ 1
% of Loan Class		0.02%	0.02%	0.02%
Total consumer | Other consumer | Repayment Plan
Financing Receivable [Line Items]
Amortized cost basis, modified		$ 1	$ 1	$ 1