Loans and Related Allowance for Credit Losses - (Subsequently Defaulted FDM) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2024
Financing Receivable [Line Items]
Subsequently default	$ 96	$ 246
Term Extension
Financing Receivable [Line Items]
Subsequently default	62	89
Payment Delay
Financing Receivable [Line Items]
Subsequently default	18	80
Repayment Plan
Financing Receivable [Line Items]
Subsequently default	8	25
Payment Delay and Term Extension
Financing Receivable [Line Items]
Subsequently default	3	40
Other
Financing Receivable [Line Items]
Subsequently default	5	12
Total commercial
Financing Receivable [Line Items]
Subsequently default	68	174
Total commercial | Term Extension
Financing Receivable [Line Items]
Subsequently default	62	89
Total commercial | Payment Delay
Financing Receivable [Line Items]
Subsequently default	3	45
Total commercial | Payment Delay and Term Extension
Financing Receivable [Line Items]
Subsequently default	3	40
Total commercial | Commercial and industrial
Financing Receivable [Line Items]
Subsequently default	41	76
Total commercial | Commercial and industrial | Term Extension
Financing Receivable [Line Items]
Subsequently default	35	61
Total commercial | Commercial and industrial | Payment Delay
Financing Receivable [Line Items]
Subsequently default	3	12
Total commercial | Commercial and industrial | Payment Delay and Term Extension
Financing Receivable [Line Items]
Subsequently default	3	3
Total commercial | Commercial real estate
Financing Receivable [Line Items]
Subsequently default	27	98
Total commercial | Commercial real estate | Term Extension
Financing Receivable [Line Items]
Subsequently default	27	28
Total commercial | Commercial real estate | Payment Delay
Financing Receivable [Line Items]
Subsequently default		33
Total commercial | Commercial real estate | Payment Delay and Term Extension
Financing Receivable [Line Items]
Subsequently default		37
Total consumer
Financing Receivable [Line Items]
Subsequently default	28	72
Total consumer | Payment Delay
Financing Receivable [Line Items]
Subsequently default	15	35
Total consumer | Repayment Plan
Financing Receivable [Line Items]
Subsequently default	8	25
Total consumer | Other
Financing Receivable [Line Items]
Subsequently default	5	12
Total consumer | Residential real estate
Financing Receivable [Line Items]
Subsequently default	17	38
Total consumer | Residential real estate | Payment Delay
Financing Receivable [Line Items]
Subsequently default	14	33
Total consumer | Residential real estate | Other
Financing Receivable [Line Items]
Subsequently default	3	5
Total consumer | Home equity
Financing Receivable [Line Items]
Subsequently default	3	10
Total consumer | Home equity | Payment Delay
Financing Receivable [Line Items]
Subsequently default	1	2
Total consumer | Home equity | Repayment Plan
Financing Receivable [Line Items]
Subsequently default		1
Total consumer | Home equity | Other
Financing Receivable [Line Items]
Subsequently default	2	7
Total consumer | Credit card
Financing Receivable [Line Items]
Subsequently default	8	24
Total consumer | Credit card | Repayment Plan
Financing Receivable [Line Items]
Subsequently default	$ 8	$ 24