Loans and Related Allowance for Credit Losses (Modified, Amortized Cost Basis) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 1,096	$ 1,196
% of Loan Class	0.34%	0.37%
Unfunded lending related commitments	$ 200	$ 100
Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	829	832
Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	103	186
Repayment Plan
Financing Receivable [Line Items]
Amortized cost basis, modified	20	23
Payment Delay and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	1	92
Interest Rate Reduction and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	3	10
Interest Rate Reduction and Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	0	14
Interest Rate Reduction, Payment Delay, and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	13	0
Other
Financing Receivable [Line Items]
Amortized cost basis, modified	127	39
Commercial and industrial | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	486	480
Commercial and industrial | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	87	126
Commercial real estate | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	355	452
Commercial real estate | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified		121
Residential real estate | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	2
Residential real estate | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	27	40
Home equity | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	2	5
Education | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	2	2
Other consumer | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	1
Other consumer | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	1
Commercial Portfolio Segment
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 1,036	$ 1,118
% of Loan Class	0.47%	0.51%
Commercial Portfolio Segment | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 826	$ 830
Commercial Portfolio Segment | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	74	141
Commercial Portfolio Segment | Repayment Plan
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Commercial Portfolio Segment | Payment Delay and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	0	92
Commercial Portfolio Segment | Interest Rate Reduction and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	2	10
Commercial Portfolio Segment | Interest Rate Reduction and Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	0	14
Commercial Portfolio Segment | Interest Rate Reduction, Payment Delay, and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	13	0
Commercial Portfolio Segment | Other
Financing Receivable [Line Items]
Amortized cost basis, modified	121	31
Commercial Portfolio Segment | Commercial and industrial
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 667	$ 610
% of Loan Class	0.37%	0.35%
Commercial Portfolio Segment | Commercial and industrial | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 471	$ 443
Commercial Portfolio Segment | Commercial and industrial | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	74	85
Commercial Portfolio Segment | Commercial and industrial | Repayment Plan
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Commercial Portfolio Segment | Commercial and industrial | Payment Delay and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	0	27
Commercial Portfolio Segment | Commercial and industrial | Interest Rate Reduction and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	2	10
Commercial Portfolio Segment | Commercial and industrial | Interest Rate Reduction and Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	0	14
Commercial Portfolio Segment | Commercial and industrial | Interest Rate Reduction, Payment Delay, and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	13	0
Commercial Portfolio Segment | Commercial and industrial | Other
Financing Receivable [Line Items]
Amortized cost basis, modified	107	31
Commercial Portfolio Segment | Commercial real estate
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 369	$ 508
% of Loan Class	1.14%	1.43%
Commercial Portfolio Segment | Commercial real estate | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 355	$ 387
Commercial Portfolio Segment | Commercial real estate | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	0	56
Commercial Portfolio Segment | Commercial real estate | Repayment Plan
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Commercial Portfolio Segment | Commercial real estate | Payment Delay and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	0	65
Commercial Portfolio Segment | Commercial real estate | Interest Rate Reduction and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Commercial Portfolio Segment | Commercial real estate | Interest Rate Reduction and Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Commercial Portfolio Segment | Commercial real estate | Interest Rate Reduction, Payment Delay, and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Commercial Portfolio Segment | Commercial real estate | Other
Financing Receivable [Line Items]
Amortized cost basis, modified	14	0
Consumer Portfolio Segment
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 60	$ 78
% of Loan Class	0.06%	0.08%
Consumer Portfolio Segment | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 3	$ 2
Consumer Portfolio Segment | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	29	45
Consumer Portfolio Segment | Repayment Plan
Financing Receivable [Line Items]
Amortized cost basis, modified	20	23
Consumer Portfolio Segment | Payment Delay and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	1	0
Consumer Portfolio Segment | Interest Rate Reduction and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	1	0
Consumer Portfolio Segment | Interest Rate Reduction and Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Consumer Portfolio Segment | Interest Rate Reduction, Payment Delay, and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Consumer Portfolio Segment | Other
Financing Receivable [Line Items]
Amortized cost basis, modified	6	8
Consumer Portfolio Segment | Residential real estate
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 30	$ 43
% of Loan Class	0.07%	0.09%
Consumer Portfolio Segment | Residential real estate | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 1	$ 0
Consumer Portfolio Segment | Residential real estate | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	27	40
Consumer Portfolio Segment | Residential real estate | Repayment Plan
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Consumer Portfolio Segment | Residential real estate | Payment Delay and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Consumer Portfolio Segment | Residential real estate | Interest Rate Reduction and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	1	0
Consumer Portfolio Segment | Residential real estate | Interest Rate Reduction and Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Consumer Portfolio Segment | Residential real estate | Interest Rate Reduction, Payment Delay, and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Consumer Portfolio Segment | Residential real estate | Other
Financing Receivable [Line Items]
Amortized cost basis, modified	1	3
Consumer Portfolio Segment | Home equity
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 7	$ 11
% of Loan Class	0.03%	0.04%
Consumer Portfolio Segment | Home equity | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 0	$ 0
Consumer Portfolio Segment | Home equity | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	2	5
Consumer Portfolio Segment | Home equity | Repayment Plan
Financing Receivable [Line Items]
Amortized cost basis, modified	0	1
Consumer Portfolio Segment | Home equity | Payment Delay and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Consumer Portfolio Segment | Home equity | Interest Rate Reduction and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Consumer Portfolio Segment | Home equity | Interest Rate Reduction and Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Consumer Portfolio Segment | Home equity | Interest Rate Reduction, Payment Delay, and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Consumer Portfolio Segment | Home equity | Other
Financing Receivable [Line Items]
Amortized cost basis, modified	5	5
Consumer Portfolio Segment | Credit card
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 20	$ 22
% of Loan Class	0.31%	0.32%
Consumer Portfolio Segment | Credit card | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 0	$ 0
Consumer Portfolio Segment | Credit card | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Consumer Portfolio Segment | Credit card | Repayment Plan
Financing Receivable [Line Items]
Amortized cost basis, modified	20	22
Consumer Portfolio Segment | Credit card | Payment Delay and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Consumer Portfolio Segment | Credit card | Interest Rate Reduction and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Consumer Portfolio Segment | Credit card | Interest Rate Reduction and Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Consumer Portfolio Segment | Credit card | Interest Rate Reduction, Payment Delay, and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Consumer Portfolio Segment | Credit card | Other
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Consumer Portfolio Segment | Education
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 2	$ 2
% of Loan Class	0.13%	0.11%
Consumer Portfolio Segment | Education | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 2	$ 2
Consumer Portfolio Segment | Education | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Consumer Portfolio Segment | Education | Repayment Plan
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Consumer Portfolio Segment | Education | Payment Delay and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Consumer Portfolio Segment | Education | Interest Rate Reduction and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Consumer Portfolio Segment | Education | Interest Rate Reduction and Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Consumer Portfolio Segment | Education | Interest Rate Reduction, Payment Delay, and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	0	0
Consumer Portfolio Segment | Education | Other
Financing Receivable [Line Items]
Amortized cost basis, modified	0	$ 0
Consumer Portfolio Segment | Other consumer
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 1
% of Loan Class	0.02%
Consumer Portfolio Segment | Other consumer | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 0
Consumer Portfolio Segment | Other consumer | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	0
Consumer Portfolio Segment | Other consumer | Repayment Plan
Financing Receivable [Line Items]
Amortized cost basis, modified	0
Consumer Portfolio Segment | Other consumer | Payment Delay and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	1
Consumer Portfolio Segment | Other consumer | Interest Rate Reduction and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	0
Consumer Portfolio Segment | Other consumer | Interest Rate Reduction and Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	0
Consumer Portfolio Segment | Other consumer | Interest Rate Reduction, Payment Delay, and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	0
Consumer Portfolio Segment | Other consumer | Other
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 0