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Financial Guaranty Variable Interest Entities and Consolidated Investment Vehicles - Additional Information (Details) | 3 Months Ended |
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Mar. 31, 2024 USD ($) Entity policy consolidatedInvestmentVehicle entity | Dec. 31, 2023 USD ($) Entity entity policy consolidatedInvestmentVehicle
Variable Interest Entity [Line Items] |  |
Number of policies monitored | policy | 15,000 |
Number of policies monitored, not within the scope of ASC 810 | policy | 14,000 |
Number of policies that contain provisions for consolidation | policy | 60 | 68
Net fair value gains and losses on FG VIEs are expected to reverse to zero at maturity of the VIE debt | $ 395,000,000 |
Variable Interest Entity, Primary Beneficiary |  |
Variable Interest Entity [Line Items] |  |
Other consolidated VIE assets |  | $ 92,000,000
Other consolidated VIE liabilities |  | $ 7,000,000
Deconsolidation, gain (loss) | 5,000,000 |
Financial Guaranty Variable Interest Entities | Variable Interest Entity, Primary Beneficiary |  |
Variable Interest Entity [Line Items] |  |
Maximum loss exposure | $ 0 |
Financial Guaranty Variable Interest Entities | Variable Interest Entity, Primary Beneficiary | Puerto Rico Trusts |  |
Variable Interest Entity [Line Items] |  |
Total number of entities consolidated | entity | 24 | 24
Financial Guaranty Variable Interest Entities | Variable Interest Entity, Primary Beneficiary | Structured Finance and Other |  |
Variable Interest Entity [Line Items] |  |
Total number of entities consolidated | Entity | 23 | 24
Puerto Rico Trusts | Variable Interest Entity, Primary Beneficiary |  |
Variable Interest Entity [Line Items] |  |
Custody receipts, notice period | 30 days |
Consolidated Investment Vehicles | Variable Interest Entity, Primary Beneficiary |  |
Variable Interest Entity [Line Items] |  |
Total number of entities consolidated | consolidatedInvestmentVehicle | 3 | 3
Consolidated Investment Vehicles | Average | Variable Interest Entity, Primary Beneficiary |  |
Variable Interest Entity [Line Items] |  |
Collateral posting requirement | $ 38,000,000 | $ 41,000,000

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