Derivatives - Schedule of Gains/(Losses) on Derivatives Associated with Cash Flow Hedges and Mortgage Banking Hedges (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Derivative Instruments, Gain (Loss) [Line Items]
Loss expected to be reclassified to earnings in the next twelve months			$ 27
Cash Flow Hedges \| Hedging Instruments and Hedged Items:
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss), cash flow hedges	$ (13)	$ 7	(30)	$ 25
Gain (loss) reclassified from AOCI into interest income	6	9	13	18
Interest rate contracts \| Cash Flow Hedges \| Hedging Instruments and Hedged Items:
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses), cash flow hedges	(9)	21	(24)	57
Option contracts written \| Mortgage Banking Hedges \| Hedging Instruments and Hedged Items:
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivative instruments	(1)	0	(2)	(1)
Forward contracts written \| Mortgage Banking Hedges \| Hedging Instruments and Hedged Items:
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivative instruments	$ 0	$ 0	$ 1	$ (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, after tax and before reclassification, of gain (loss) from derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

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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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