Derivative Instruments and Hedging Activities (Derivative Gain (Loss) Recognized/Reclassified) (Details) - USD ($)	3 Months Ended	9 Months Ended
Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion of derivative gain/(loss) deferred in AOCI	$ (172,000,000)
Amount of gain/(loss) reclassified from AOCI into income	(8,000,000)	$ 12,000,000	$ 7,000,000	$ 35,000,000
Gain (loss) to be reclassified within the next 12 months into interest income			(173,000,000)	42,000,000
Derivatives designated as hedges
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion of derivative gain/(loss) deferred in AOCI	(183,000,000)	4,000,000	(427,000,000)	(5,000,000)
Amount of gain/(loss) reclassified from AOCI into income	(11,000,000)	16,000,000	9,000,000	46,000,000
Interest on fair value hedges	0	4,000,000	2,000,000	13,000,000
Derivatives designated as hedges \| Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Terminated or redesignated, unamortized basis adjustments	10,000,000	7,000,000	10,000,000	7,000,000
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	0	0
Amount of gain/(loss) reclassified from AOCI into income	0	3,000,000	2,000,000	8,000,000
Interest on fair value hedges	0	0	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	(183,000,000)	4,000,000	(427,000,000)	(5,000,000)
Amount of gain/(loss) reclassified from AOCI into income	(11,000,000)	13,000,000	7,000,000	38,000,000
Interest on fair value hedges	0	0	0	0
Derivatives designated as hedges \| Fair Value Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Terminated or redesignated, unamortized basis adjustments	0	2,000,000	0	2,000,000
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	0	0
Amount of gain/(loss) reclassified from AOCI into income	0	0	0	0
Interest on fair value hedges	(1,000,000)	2,000,000	2,000,000	6,000,000
Derivatives designated as hedges \| Fair Value Hedging \| Basis amortization on terminated hedges
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion of derivative gain/(loss) deferred in AOCI	0	0	0	0
Amount of gain/(loss) reclassified from AOCI into income	0	0	0	0
Interest on fair value hedges	0	3,000,000	1,000,000	9,000,000
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	0	0
Amount of gain/(loss) reclassified from AOCI into income	0	0	0	0
Interest on fair value hedges	1,000,000	(1,000,000)	(1,000,000)	(2,000,000)
Derivatives designated as hedges \| Fair Value Hedging \| Basis amortization on terminated hedges
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion of derivative gain/(loss) deferred in AOCI	0	0	0	0
Amount of gain/(loss) reclassified from AOCI into income	0	0	0	0
Interest on fair value hedges	0	0	0	0
Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Interest on fair value hedges	19,000,000	16,000,000	63,000,000	39,000,000
Derivatives not designated as hedging instruments \| Interest Rate Swaps For Customers
Derivative Instruments, Gain (Loss) [Line Items]
Interest on fair value hedges	(227,000,000)	(5,000,000)	(638,000,000)	(100,000,000)
Derivatives not designated as hedging instruments \| Offsetting interest rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Interest on fair value hedges	238,000,000	12,000,000	680,000,000	129,000,000
Derivatives not designated as hedging instruments \| Other interest rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Interest on fair value hedges	0	3,000,000	0	(7,000,000)
Derivatives not designated as hedging instruments \| Foreign exchange derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Interest on fair value hedges	$ 8,000,000	$ 6,000,000	$ 21,000,000	$ 17,000,000

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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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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