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Financial Guaranty Variable Interest Entities and Consolidated Investment Vehicles - Roll Forward of Number of Consolidated CIVs (Details) (Details) - Variable Interest Entity, Primary Beneficiary - Consolidated Investment Vehicles $ in Millions | 12 Months Ended
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Dec. 31, 2022 USD ($) Entity | Dec. 31, 2021 Entity | Dec. 31, 2020 Entity
Schedule of Consolidated FG VIEs Rollforward [Roll Forward] |  |  |
Beginning of year | 20 | 11 | 4
Consolidated | 4 | 10 | 7
Deconsolidated | (2) | (1) | 0
December 31 |  | 20 | 11
Deconsolidation, net assets | $ | $ 417 |  |

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