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Insurance Contracts Financial Guarantee Insurance Contracts - Components of Loss and Loss Expense Reserves and Subrogation Recoverable (Details) - USD ($) $ in Thousands | 9 Months Ended |  |
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Sep. 30, 2025 | Sep. 30, 2024 | Dec. 31, 2024 | Dec. 31, 2023
Components of Loss and Loss Expense Reserves and Subrogation Recoverable [Line Items] |  |  |  |
Ceded Loss And Loss Expenses Paid Not Yet Recovered |  | $ 41,225 |  |
Policyholder Benefits and Claims Incurred, Ceded | $ 166,959 | 72,160 |  |
Liability for Claims and Claims Adjustment Expense | 437,539 |  | $ 349,062 |
Liability for Claim and Claim Adjustment Expenses Net of Subrogation recoverables | $ 437,539 | $ 323,231 | $ 349,062 | $ 197,089

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- Definition Ceded Loss And Loss Expenses Paid Not Yet Recovered + References No definition available. + Details
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- Definition [Line Items] for Components of Loss and Loss Expense Reserves and Subrogation Recoverable [Table] + References No definition available. + Details
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