Derivative Instruments and Hedging Activities (Derivative gain (loss) recognized/reclassified) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain/(loss) reclassified from AOCI into income	$ (124)	$ (21)	$ 46
Gains to be reclassified within the next 12 months into interest income	118	205
Derivatives designated as hedges
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion of derivative gain/(loss) deferred in AOCI	35	(437)
Amount of gain/(loss) reclassified from AOCI into income	(165)	(27)
Net interest income or expense on fair value hedges	49	4
Hedge ineffectiveness / AOCI reclass due to missed forecast	0	(1)
Derivatives designated as hedges \| Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Terminated or redesignated, unamortized basis adjustments	3	10
Derivatives designated as hedges \| Cash Flow Hedging \| Purchased interest rate floors
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion of derivative gain/(loss) deferred in AOCI	0	0
Amount of gain/(loss) reclassified from AOCI into income	0	2
Net interest income or expense on fair value hedges	0	0
Hedge ineffectiveness / AOCI reclass due to missed forecast	0	0
Derivatives designated as hedges \| Cash Flow Hedging \| Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion of derivative gain/(loss) deferred in AOCI	31	(437)
Amount of gain/(loss) reclassified from AOCI into income	(170)	(29)
Net interest income or expense on fair value hedges	0	0
Hedge ineffectiveness / AOCI reclass due to missed forecast	0	0
Derivatives designated as hedges \| Cash Flow Hedging \| Receive-fixed interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion of derivative gain/(loss) deferred in AOCI	4
Amount of gain/(loss) reclassified from AOCI into income	5
Net interest income or expense on fair value hedges	0
Hedge ineffectiveness / AOCI reclass due to missed forecast	0
Derivatives designated as hedges \| Fair Value Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Terminated or redesignated, unamortized basis adjustments	46	0
Derivatives designated as hedges \| Fair Value Hedging \| Receive-fixed interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion of derivative gain/(loss) deferred in AOCI	0	0
Amount of gain/(loss) reclassified from AOCI into income	0	0
Net interest income or expense on fair value hedges	(5)	(1)
Hedge ineffectiveness / AOCI reclass due to missed forecast	0	0
Derivatives designated as hedges \| Fair Value Hedging \| Basis amortization on terminated hedges, liability hedges
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion of derivative gain/(loss) deferred in AOCI	0	0
Amount of gain/(loss) reclassified from AOCI into income	0	0
Net interest income or expense on fair value hedges	(4)	1
Hedge ineffectiveness / AOCI reclass due to missed forecast	0	0
Derivatives designated as hedges \| Fair Value Hedging \| Pay-fixed interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion of derivative gain/(loss) deferred in AOCI	0	0
Amount of gain/(loss) reclassified from AOCI into income	0	0
Net interest income or expense on fair value hedges	57	4
Hedge ineffectiveness / AOCI reclass due to missed forecast	0	(1)
Derivatives designated as hedges \| Fair Value Hedging \| Basis amortization on terminated hedges, asset hedges
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion of derivative gain/(loss) deferred in AOCI	0	0
Amount of gain/(loss) reclassified from AOCI into income	0	0
Net interest income or expense on fair value hedges	1	0
Hedge ineffectiveness / AOCI reclass due to missed forecast	$ 0	$ 0

The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

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The amount of net gain (loss) reclassified into earnings when interest rate cash flow hedge is discontinued because it is probable that the original forecasted transactions will not occur by the end of the original period or an additional two month time period.

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Amount, before tax and reclassification, of gain (loss) from derivative instrument designated and qualifying cash flow hedge included in assessment of hedge effectiveness.

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Amount, after 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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Derivative instrument noninterest income (expense)

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Terminated And Redesignated Swaps, Unamortized Basis Adjustments

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