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Derivatives (Narrative) (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024 | Dec. 31, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract] |  |  |  |  |
Counterparty default losses on forward contracts | $ 0 | $ 0 | $ 0 | $ 0 |
Credit Derivatives [Line Items] |  |  |  |  |
Commitments |  |  |  |  |
Collateral required to be posted under agreements | 89 |  | 89 |  | 87
Variation Margin Adjustment | 107 |  | 107 |  | 174
Interest rate futures |  |  |  |  |
Credit Derivatives [Line Items] |  |  |  |  |
Derivative, notional amount | 194 |  | 194 |  | 187
Mortgage-Backed Security |  |  |  |  |
Credit Derivatives [Line Items] |  |  |  |  |
Derivative, notional amount | 36 |  | 36 |  | 12
Interest rate swaps |  |  |  |  |
Credit Derivatives [Line Items] |  |  |  |  |
Derivative Asset, Notional Amount | 4,500 |  | 4,500 |  | 4,300
Derivative Liability, Notional Amount | 4,500 |  | 4,500 |  | 4,400
Commitments To Originate Loans Held For Sale |  |  |  |  |
Credit Derivatives [Line Items] |  |  |  |  |
Commitments | 59 |  | 59 |  | 46
Interest rate forward sales commitments |  |  |  |  |
Credit Derivatives [Line Items] |  |  |  |  |
Commitments | $ 82 |  | $ 82 |  | $ 77

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