Investment Securities - Additional Information (Details) - USD ($)			3 Months Ended	9 Months Ended
Sep. 30, 2025	Dec. 31, 2024	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Debt Securities, Available-for-sale [Line Items]
Accrued interest receivable	$ 302,000,000	$ 262,000,000
Proceeds from sales of securities related to the Transaction			$ 0		$ 9,696,000,000	$ 0
Debt securities, available-for-sale, gain (loss)			0	$ (35,000,000)	0	(35,000,000)
Proceeds from sales				$ 175,000,000	1,000,000	$ 175,000,000
Investment securities	37,400,000,000	39,400,000,000	37,400,000,000		37,400,000,000
Securities received as collateral	$ 1,000,000	$ 18,000,000	$ 1,000,000		$ 1,000,000
Investment securities available for sale \| Government Contracts Concentration Risk \| US Treasury and Agency securities
Debt Securities, Available-for-sale [Line Items]
Percentage of portfolio	97.00%	96.00%

Proceeds from Sale of Debt Securities, Related to Transaction

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

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- Definition

Amount of interest income on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), from change in present value of expected cash flows, attributable to passage of time.

+ References

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- Definition

Amount of unrealized and realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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- Definition

Amount of cash inflow from sale of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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- Definition

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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- Definition

The carrying value as of the balance sheet date of the assets received as collateral against securities loaned to other broker-dealers. Borrowers of securities generally are required to provide collateral to the lenders of securities, commonly cash but sometimes other securities or standby letters of credit, with a value slightly higher than that of the securities borrowed. In instances where the entity is permitted to sell or re-pledge these securities, the entity reports the fair value of the collateral received and the related obligation to return the collateral as a liability.

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Fair value of liabilities arising from or related to a financial instrument held by the entity for its own account (proprietary securities) which has been pledged to counterparties.

+ References

No definition available.

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