Loans and Related Allowance for Credit Losses (Subsequent Default) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	$ 331
Rate Reduction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	47
Term Extension
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	53
Payment Delay
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	196
Other
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	35
Total commercial lending
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	272
Total commercial lending | Rate Reduction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	46
Total commercial lending | Term Extension
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	53
Total commercial lending | Payment Delay
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	166
Total commercial lending | Other
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	7
Total commercial lending | Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	211
Total commercial lending | Commercial and industrial | Term Extension
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	38
Total commercial lending | Commercial and industrial | Payment Delay
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	166
Total commercial lending | Commercial and industrial | Other
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	7
Total commercial lending | Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	61
Total commercial lending | Commercial real estate | Rate Reduction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	46
Total commercial lending | Commercial real estate | Term Extension
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	15
Total consumer lending
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	59
Total consumer lending | Rate Reduction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	1
Total consumer lending | Term Extension
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default
Total consumer lending | Payment Delay
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	30
Total consumer lending | Other
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	28
Total consumer lending | Residential real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	31
Total consumer lending | Residential real estate | Rate Reduction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	1
Total consumer lending | Residential real estate | Term Extension
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default
Total consumer lending | Residential real estate | Payment Delay
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	28
Total consumer lending | Residential real estate | Other
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	2
Total consumer lending | Home equity
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	12
Total consumer lending | Home equity | Payment Delay
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	2
Total consumer lending | Home equity | Other
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	10
Total consumer lending | Credit card
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	16
Total consumer lending | Credit card | Other
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default	$ 16