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Contracts Accounted for as Financial Guaranty Insurance - Additional Information (Details) | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2026 | Dec. 31, 2025
Guarantor Obligations [Line Items] |  |
Weighted average risk-free rates for U.S. dollar denominated financial guaranty insurance obligations | 4.17% | 3.93%
Minimum |  |
Guarantor Obligations [Line Items] |  |
Weighted average risk-free rates for U.S. dollar denominated financial guaranty insurance obligations | 1.93% | 1.93%
Maximum |  |
Guarantor Obligations [Line Items] |  |
Weighted average risk-free rates for U.S. dollar denominated financial guaranty insurance obligations | 5.68% | 5.35%
Foreign Currency Concentration Risk | Premiums Receivable | Premiums Receivable |  |
Guarantor Obligations [Line Items] |  |
Percentage of installment premiums denominated in currencies other than the U.S. dollar | 67.00% | 68.00%

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