Loans and Related Allowance for Credit Losses (Financial Effect of Loan Modification) (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
Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	827	595	1,502	927
Interest Rate Reduction
Financing Receivable [Line Items]
Amortized cost basis, modified	18	1	18	1
Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	129	97	171	148
Principal Forgiveness
Financing Receivable [Line Items]
Amortized cost basis, modified				1
Commercial and industrial | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 539	$ 366	$ 941	$ 432
Weighted average extended contract term	15 months	9 months	14 months	10 months
Commercial and industrial | Interest Rate Reduction
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 120		$ 145
Weighted average interest rate reduction	1.12%		1.64%
Commercial and industrial | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 159	$ 59	$ 207	$ 72
Weighted average payment deferral term	5 months	10 months	7 months	6 months
Commercial and industrial | Principal Forgiveness
Financing Receivable [Line Items]
Amortized cost basis, modified				$ 1
Principal balance forgiven				2
Commercial real estate | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 538	$ 228	$ 927	$ 493
Weighted average extended contract term	14 months	20 months	14 months	17 months
Commercial real estate | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 84		$ 173
Weighted average payment deferral term	23 months		9 months
Residential real estate | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 1	$ 1	$ 1	$ 2
Weighted average extended contract term	105 months	123 months	98 months	111 months
Residential real estate | Interest Rate Reduction
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 1	$ 2	$ 1	$ 3
Weighted average interest rate reduction	1.30%	1.17%	1.15%	1.34%
Residential real estate | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 30	$ 35	$ 55	$ 72
Weighted average payment deferral term	10 months	8 months	9 months	8 months
Home equity | Payment Delay
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 5	$ 3	$ 8	$ 4
Weighted average payment deferral term	5 months	3 months	4 months	4 months
Education | Term Extension
Financing Receivable [Line Items]
Amortized cost basis, modified	$ 1	$ 1	$ 3	$ 2
Weighted average extended contract term	16 months	19 months	12 months	17 months