Derivative Instruments and Hedging Activities - Effect of Fair Value Hedge Derivatives (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Interest income, receipts	$ 1	$ 14	$ 2	$ 32
Interest expense, receipts	(11)	(14)	(6)	(24)
Interest rate swaps \| Location, Statement of Income, Balance [Axis]: us-gaap:InterestExpenseOperating
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivatives designated as hedging instruments	(134)	(9)	(241)	18
Interest rate swaps \| Location, Statement of Income, Balance [Axis]: us-gaap:InterestIncomeOperating
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivatives designated as hedging instruments	76	(94)	107	(255)
Debt Securities and Hedged Available-for-Sale Securities \| Location, Statement of Income, Balance [Axis]: us-gaap:InterestIncomeOperating
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged items	(76)	94	(107)	255
Long-term debt \| Location, Statement of Income, Balance [Axis]: us-gaap:InterestExpenseOperating
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged items	$ 134	$ 9	$ 241	$ (16)

Interest Expense, Fair Value Hedge Derivative Instrument, Increase (Decrease)

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- Definition

Interest Income, Fair Value Hedge Derivative Instrument, Increase (Decrease)

+ References

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- Definition

Amount of gain (loss) from the increase (decrease) in fair value of derivative and nonderivative instruments designated as fair value hedging instruments recognized in the income statement.

+ References

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- Definition

Amount of the increase (decrease) in fair value of the hedged item in a fair value hedge recognized in the income statement.

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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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