Loans and Related Allowance for Credit Losses - (Subsequently Defaulted FDM) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Financing Receivable [Line Items]
Subsequently default	$ 71	$ 49
Term Extension
Financing Receivable [Line Items]
Subsequently default	43
Payment Delay
Financing Receivable [Line Items]
Subsequently default	16
Repayment Plan
Financing Receivable [Line Items]
Subsequently default	7
All Other Modifications
Financing Receivable [Line Items]
Subsequently default	5
Commercial Portfolio Segment
Financing Receivable [Line Items]
Subsequently default	44
Commercial Portfolio Segment | Term Extension
Financing Receivable [Line Items]
Subsequently default	43
Commercial Portfolio Segment | Payment Delay
Financing Receivable [Line Items]
Subsequently default	0
Commercial Portfolio Segment | Repayment Plan
Financing Receivable [Line Items]
Subsequently default	0
Commercial Portfolio Segment | All Other Modifications
Financing Receivable [Line Items]
Subsequently default	1
Commercial Portfolio Segment | Commercial and industrial
Financing Receivable [Line Items]
Subsequently default	28
Commercial Portfolio Segment | Commercial and industrial | Term Extension
Financing Receivable [Line Items]
Subsequently default	27
Commercial Portfolio Segment | Commercial and industrial | Payment Delay
Financing Receivable [Line Items]
Subsequently default	0
Commercial Portfolio Segment | Commercial and industrial | Repayment Plan
Financing Receivable [Line Items]
Subsequently default	0
Commercial Portfolio Segment | Commercial and industrial | All Other Modifications
Financing Receivable [Line Items]
Subsequently default	1
Commercial Portfolio Segment | Commercial real estate
Financing Receivable [Line Items]
Subsequently default	16
Commercial Portfolio Segment | Commercial real estate | Term Extension
Financing Receivable [Line Items]
Subsequently default	16
Commercial Portfolio Segment | Commercial real estate | Payment Delay
Financing Receivable [Line Items]
Subsequently default	0
Commercial Portfolio Segment | Commercial real estate | Repayment Plan
Financing Receivable [Line Items]
Subsequently default	0
Commercial Portfolio Segment | Commercial real estate | All Other Modifications
Financing Receivable [Line Items]
Subsequently default	0
Consumer Portfolio Segment
Financing Receivable [Line Items]
Subsequently default	27
Consumer Portfolio Segment | Term Extension
Financing Receivable [Line Items]
Subsequently default	0
Consumer Portfolio Segment | Payment Delay
Financing Receivable [Line Items]
Subsequently default	16
Consumer Portfolio Segment | Repayment Plan
Financing Receivable [Line Items]
Subsequently default	7
Consumer Portfolio Segment | All Other Modifications
Financing Receivable [Line Items]
Subsequently default	4
Consumer Portfolio Segment | Residential real estate
Financing Receivable [Line Items]
Subsequently default	16
Consumer Portfolio Segment | Residential real estate | Term Extension
Financing Receivable [Line Items]
Subsequently default	0
Consumer Portfolio Segment | Residential real estate | Payment Delay
Financing Receivable [Line Items]
Subsequently default	15
Consumer Portfolio Segment | Residential real estate | Repayment Plan
Financing Receivable [Line Items]
Subsequently default	0
Consumer Portfolio Segment | Residential real estate | All Other Modifications
Financing Receivable [Line Items]
Subsequently default	1
Consumer Portfolio Segment | Home equity
Financing Receivable [Line Items]
Subsequently default	4
Consumer Portfolio Segment | Home equity | Term Extension
Financing Receivable [Line Items]
Subsequently default	0
Consumer Portfolio Segment | Home equity | Payment Delay
Financing Receivable [Line Items]
Subsequently default	1
Consumer Portfolio Segment | Home equity | Repayment Plan
Financing Receivable [Line Items]
Subsequently default	0
Consumer Portfolio Segment | Home equity | All Other Modifications
Financing Receivable [Line Items]
Subsequently default	3
Consumer Portfolio Segment | Credit card
Financing Receivable [Line Items]
Subsequently default	7
Consumer Portfolio Segment | Credit card | Term Extension
Financing Receivable [Line Items]
Subsequently default	0
Consumer Portfolio Segment | Credit card | Payment Delay
Financing Receivable [Line Items]
Subsequently default	0
Consumer Portfolio Segment | Credit card | Repayment Plan
Financing Receivable [Line Items]
Subsequently default	7
Consumer Portfolio Segment | Credit card | All Other Modifications
Financing Receivable [Line Items]
Subsequently default	$ 0