Fair Value Measurements - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Gains from sale of other real estate classified as OREO	$ 6		$ 6
Gain resulting from observable price changes	0	$ 2	4	$ 11
Positive adjustments, cumulative amount	23		23
Private equity, impairment	0	$ 0	0	0
Private equity, cumulative impairment	$ 15		15
Residential Mortgage
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value changes included in earnings for instruments for which the fair value option was elected			$ (24)	$ 2

Amount of impairment loss on investment in equity security without readily determinable fair value.

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Amount of gain from upward price adjustment on investment in equity security without readily determinable fair value.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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For each line item in the statement of financial position, the amounts of gains and losses from fair value changes included in earnings.

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The net gain (loss) resulting from sales and other disposals of other real estate owned, increases (decreases) in the valuation allowance for foreclosed real estate, and write-downs of other real estate owned after acquisition or physical possession.

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