Fair Value (Level 3) (Details) - Subtotal PLRMBS - Fair Value, Measurements, Recurring - Level 3 - Available-for-sale Securities - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of the period	$ 881	$ 957
Interest income	3	3
(Provision for)/reversal of credit losses	0	(1)
Unrealized gain/(loss) included in AOCI	(7)	2
Settlements	(27)	(19)
Balance, end of the period	850	942
Total amount of unrealized gain/(loss) for the period included in AOCI relating to assets held at the end of the period	(7)	2
Total amount of gain/(loss) for the period included in earnings relating to assets held at the end of the period	$ 3	$ 2

Amount of unrealized gain (loss) recognized in other comprehensive income (OCI) from asset measured at fair value on recurring basis using unobservable input (level 3) and still held.

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Amount of gain (loss) recognized in income from asset and liability measured at fair value on recurring basis using unobservable input (level 3).

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3).

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Amount of gain (loss) recognized in other comprehensive income (OCI) from asset measured at fair value on recurring basis using unobservable input (level 3).

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Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of expense related to credit loss from transactions other than loan and lease transactions.

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