Fair Value Measurements - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Net fair value of the interest rate lock commitments	$ 6		$ 6
Change in the fair value of the interest rate lock commitments, due to decrease in current interest rates of 25 bps	2		2
Change in the fair value of the interest rate lock commitments, due to decrease in current interest rates of 50 bps	4		4
Change in the fair value of the interest rate lock commitments, due to increase in current interest rates of 25 bps	3		3
Change in the fair value of the interest rate lock commitments, due to increase in current interest rates of 50 bps	6		6
Change in fair value of interest rate lock commitments, due to 20% favorable changes in the assumed loan closing rates	0		0
Change in fair value of interest rate lock commitments, due to 20% adverse changes in the assumed loan closing rates	0		0
Change in fair value of interest rate lock commitments, due to 10% favorable changes in the assumed loan closing rates	0		0
Change in fair value of interest rate lock commitments, due to 10% adverse changes in the assumed loan closing rates	0		0
Gain resulting from observable price changes	2	$ 0	11	$ 0
Positive adjustments, cumulative amount	20		20
Private equity, impairment	0	$ 0	0	2
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			2	$ (24)
FVO valuation adjustments related to instrument-specific credit risk			$ 0		$ 0

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Fair values as of the balance sheet date of the net amount of all assets and liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments.

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

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Amount of cumulative 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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