Derivatives and Hedging Activities - Schedule of Effect of Fair Value and Cash Flow Hedges on Income (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025
Derivative Instruments, Gain (Loss) [Line Items]
Interest expense — Long-term debt	$ (151)	$ (193)
Interest income – loans	1,416	1,401
Interest Income - securities	370	392
Investment banking and debt placement fees	197	175
Interest rate \| Interest expense – long-term debt \| Fair Value Hedging
Net gains (losses) on fair value hedging relationships
Recognized on hedged items	29	(153)
Recognized on derivatives designated as hedging instruments	(51)	108
Net income (expense) recognized on fair value hedges	(22)	(45)
Interest rate \| Interest expense – long-term debt \| Cash Flow Hedging
Net gain (loss) on cash flow hedging relationships
Realized gains (losses) (pre-tax) reclassified from AOCI into net income	(1)	(1)
Net income (expense) recognized on cash flow hedges	(1)	(1)
Interest rate \| Interest income – loans \| Fair Value Hedging
Net gains (losses) on fair value hedging relationships
Recognized on hedged items	0	0
Recognized on derivatives designated as hedging instruments	0	0
Net income (expense) recognized on fair value hedges	0	0
Interest rate \| Interest income – loans \| Cash Flow Hedging
Net gain (loss) on cash flow hedging relationships
Realized gains (losses) (pre-tax) reclassified from AOCI into net income	(36)	(93)
Net income (expense) recognized on cash flow hedges	(36)	(93)
Interest rate \| Interest Income - securities \| Fair Value Hedging
Net gains (losses) on fair value hedging relationships
Recognized on hedged items	(61)	78
Recognized on derivatives designated as hedging instruments	51	(71)
Net income (expense) recognized on fair value hedges	(10)	7
Interest rate \| Interest Income - securities \| Cash Flow Hedging
Net gain (loss) on cash flow hedging relationships
Realized gains (losses) (pre-tax) reclassified from AOCI into net income	0	0
Net income (expense) recognized on cash flow hedges	0	0
Interest rate \| Investment banking and debt placement fees \| Fair Value Hedging
Net gains (losses) on fair value hedging relationships
Recognized on hedged items	0	0
Recognized on derivatives designated as hedging instruments	0	0
Net income (expense) recognized on fair value hedges	0	0
Interest rate \| Investment banking and debt placement fees \| Cash Flow Hedging
Net gain (loss) on cash flow hedging relationships
Realized gains (losses) (pre-tax) reclassified from AOCI into net income	0	0
Net income (expense) recognized on cash flow hedges	$ 0	$ 0

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