Derivatives and Hedging Activities - Effect of Fair Value and Cash Flow Hedges on Income (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Derivative Instruments, Gain (Loss) [Line Items]
Interest expense — Long-term debt	$ (1,305)	$ (475)	$ (221)
Interest income — Loans	6,219	4,241	3,532
Interest Income - securities	793	752	546
Investment banking and debt placement fees	542	638	937
Investment banking and debt placement fees \| Fair Value Hedging
Gain (Loss) on Fair Value Hedges Recognized in Earnings [Abstract]
Net income (expense) recognized on fair value hedges		0
Investment banking and debt placement fees \| Cash Flow Hedging
Cash Flow Hedges Derivative Instruments at Fair Value, Net [Abstract]
Net income (expense) recognized on cash flow hedges	5
Interest rate \| Interest expense – long-term debt \| Fair Value Hedging
Gain (Loss) on Fair Value Hedges Recognized in Earnings [Abstract]
Recognized on hedged items	(119)	690	276
Recognized on derivatives designated as hedging instruments	(135)	(697)	(150)
Net income (expense) recognized on fair value hedges	(254)	(7)	126
Interest rate \| Interest expense – long-term debt \| Cash Flow Hedging
Cash Flow Hedges Derivative Instruments at Fair Value, Net [Abstract]
Realized gains (losses) (pre-tax) reclassified from AOCI into net income	(2)	(3)	(4)
Net income (expense) recognized on cash flow hedges	(2)	(3)	(4)
Interest rate \| Interest income — Loans \| Fair Value Hedging
Gain (Loss) on Fair Value Hedges Recognized in Earnings [Abstract]
Recognized on hedged items	0	0	0
Recognized on derivatives designated as hedging instruments	0	0	0
Net income (expense) recognized on fair value hedges	0	0	0
Interest rate \| Interest income — Loans \| Cash Flow Hedging
Cash Flow Hedges Derivative Instruments at Fair Value, Net [Abstract]
Realized gains (losses) (pre-tax) reclassified from AOCI into net income	(956)	(146)	329
Net income (expense) recognized on cash flow hedges	(956)	(146)	329
Interest rate \| Interest Income - securities \| Fair Value Hedging
Gain (Loss) on Fair Value Hedges Recognized in Earnings [Abstract]
Recognized on hedged items	181	(339)	(113)
Recognized on derivatives designated as hedging instruments	(132)	350	113
Net income (expense) recognized on fair value hedges	49	11	0
Interest rate \| Interest Income - securities \| Cash Flow Hedging
Cash Flow Hedges Derivative Instruments at Fair Value, Net [Abstract]
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
Gain (Loss) on Fair Value Hedges Recognized in Earnings [Abstract]
Recognized on hedged items	0	0	0
Recognized on derivatives designated as hedging instruments	0	0	0
Net income (expense) recognized on fair value hedges	0		0
Interest rate \| Investment banking and debt placement fees \| Cash Flow Hedging
Cash Flow Hedges Derivative Instruments at Fair Value, Net [Abstract]
Realized gains (losses) (pre-tax) reclassified from AOCI into net income	$ 5	9	4
Net income (expense) recognized on cash flow hedges		$ 9	$ 4

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Amount of gain (loss) from the increase (decrease) in fair value of derivative and nonderivative instruments designated as fair value hedging instruments recognized in the income statement.

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Amount of the increase (decrease) in fair value of the hedged item in a fair value hedge recognized in the income statement.

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Interest and fee income generated by loans the Entity intends and has the ability to hold for the foreseeable future, or until maturity or payoff, including commercial and consumer loans, whether domestic or foreign, which may consist of: (1) industrial and agricultural; (2) real estate; and (3) real estate construction loans; (4) trade financing; (5) lease financing; (6) home equity lines-of-credit; (7) automobile and other vehicle loans; and (8) credit card and other revolving-type loans. Also includes interest income for leases held by the Entity.

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Aggregate amount of interest paid or due on all long-term debt.

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Amount, before tax, of reclassification of gain (loss) from accumulated other comprehensive income (AOCI) for derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

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