Loans and Related Allowance for Credit Losses (Modified, Amortized Cost Basis) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 1,196	$ 566
% of Loan Class	0.37%	0.17%
Unfunded lending related commitments	$ 100	$ 100
Principal Forgiveness
Financing Receivable [Line Items]
Amortized cost basis, modified		1
Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	832	472
Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	186	67
Repayment Plan
Financing Receivable [Line Items]
Amortized cost basis, modified	23	16
Payment Delay and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	92
Interest Rate Reduction and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	10	2
Interest Rate Reduction and Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	14
Other
Financing Receivable [Line Items]
Amortized cost basis, modified	39	8
Total commercial
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 1,118	$ 497
% of Loan Class	0.51%	0.22%
Total commercial | Principal Forgiveness
Financing Receivable [Line Items]
Amortized cost basis, modified		$ 1
Total commercial | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 830	471
Total commercial | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	141	20
Total commercial | Payment Delay and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	92
Total commercial | Interest Rate Reduction and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	10
Total commercial | Interest Rate Reduction and Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	14
Total commercial | Other
Financing Receivable [Line Items]
Amortized cost basis, modified	31	5
Total commercial | Commercial and industrial
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 610	$ 224
% of Loan Class	0.35%	0.12%
Total commercial | Commercial and industrial | Principal Forgiveness
Financing Receivable [Line Items]
Amortized cost basis, modified		$ 1
Total commercial | Commercial and industrial | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 443	198
Total commercial | Commercial and industrial | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	85	20
Total commercial | Commercial and industrial | Payment Delay and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	27
Total commercial | Commercial and industrial | Interest Rate Reduction and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	10
Total commercial | Commercial and industrial | Interest Rate Reduction and Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	14
Total commercial | Commercial and industrial | Other
Financing Receivable [Line Items]
Amortized cost basis, modified	31	5
Total commercial | Commercial real estate
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 508	$ 273
% of Loan Class	1.43%	0.76%
Total commercial | Commercial real estate | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 387	$ 273
Total commercial | Commercial real estate | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	56
Total commercial | Commercial real estate | Payment Delay and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	65
Total commercial | Commercial real estate | Other
Financing Receivable [Line Items]
Amortized cost basis, modified
Total consumer
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 78	$ 69
% of Loan Class	0.08%	0.07%
Total consumer | Principal Forgiveness
Financing Receivable [Line Items]
Amortized cost basis, modified
Total consumer | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 2	1
Total consumer | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	45	47
Total consumer | Repayment Plan
Financing Receivable [Line Items]
Amortized cost basis, modified	23	16
Total consumer | Interest Rate Reduction and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified		2
Total consumer | Other
Financing Receivable [Line Items]
Amortized cost basis, modified	8	3
Total consumer | Residential real estate
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 43	$ 49
% of Loan Class	0.09%	0.11%
Total consumer | Residential real estate | Principal Forgiveness
Financing Receivable [Line Items]
Amortized cost basis, modified
Total consumer | Residential real estate | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 40	46
Total consumer | Residential real estate | Interest Rate Reduction and Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified		2
Total consumer | Residential real estate | Other
Financing Receivable [Line Items]
Amortized cost basis, modified	3	1
Total consumer | Home equity
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 11	$ 5
% of Loan Class	0.04%	0.02%
Total consumer | Home equity | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 5	$ 1
Total consumer | Home equity | Repayment Plan
Financing Receivable [Line Items]
Amortized cost basis, modified	1	2
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	5	2
Total consumer | Credit card
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 22	$ 13
% of Loan Class	0.32%	0.19%
Total consumer | Credit card | Repayment Plan
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 22	$ 13
Total consumer | Education
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 2	$ 1
% of Loan Class	0.11%	0.05%
Total consumer | Education | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 2	$ 1
Total consumer | Other consumer
Financing Receivable [Line Items]
Amortized cost basis, modified		$ 1
% of Loan Class		0.02%
Total consumer | Other consumer | Repayment Plan
Financing Receivable [Line Items]
Amortized cost basis, modified		$ 1