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Investment Securities - Additional Information (Details) - USD ($)			3 Months Ended		9 Months Ended
	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Debt Securities, Available-for-sale [Line Items]
Accrued interest receivable	$ 264,000,000	$ 227,000,000
Proceeds from sales			$ 175,000,000	$ 0	$ 175,000,000	$ 0
Gain (loss) on debt securities, available- for-sale			(35,000,000)		(35,000,000)
Investment securities	40,100,000,000	45,100,000,000	40,100,000,000		40,100,000,000
Securities received as collateral	$ 11,000,000	$ 16,000,000	$ 11,000,000		$ 11,000,000
Investment securities available for sale | Government Contracts Concentration Risk | US Treasury and Agency securities
Debt Securities, Available-for-sale [Line Items]
Percentage of portfolio	96.00%	97.00%

X

- 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.

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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.

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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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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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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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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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