Fair Value Measurements - Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
2023 & 2025 Fixed-to-Floating Interest Rate Swaps \| Fair Value Hedging \| Designated as Hedging Instrument
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Interest rate fair value hedge asset at fair value	$ 13	$ 23
2022 Fixed-to-Floating Interest Rate Swaps \| Fair Value Hedging \| Designated as Hedging Instrument
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Interest rate fair value hedge liability at fair value	94	87
Fair Value
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities	170	182
Carrying Value
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities at amortized costs	$ 172	$ 181

Amortized cost 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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