Derivatives - Gains/(Losses) on Derivatives Associated with Cash Flow Hedges and Mortgage Banking Hedges (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Derivative Instruments, Gain (Loss) [Line Items]
Loss expected to be reclassified to earnings in the next twelve months	$ (4)	$ (4)	$ (4)	$ (4)
Cash Flow Hedge \| Hedging Instruments And Hedged Items
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses), cash flow hedges	45	(34)	(13)	(60)
Gain (loss) reclassified from AOCI into interest income	13	14	39	38
Interest Rate Swap \| Cash Flow Hedge \| Hedging Instruments And Hedged Items
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses), cash flow hedges	77	(30)	35	(44)
Option contracts written \| Mortgage Banking Hedges \| Hedging Instruments And Hedged Items
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivative instruments	0	0	0	(2)
Forward contracts written \| Mortgage Banking Hedges \| Hedging Instruments And Hedged Items
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivative instruments	$ 3	$ (2)	$ (5)	$ 2

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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Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects.

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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, 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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