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Variable Interest Entities (Details) - USD ($) $ in Millions | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2025 | Dec. 31, 2024
Schedule of Equity Method Investments [Line Items] |  |
Surplus Notes and Guarantee Fund Certificates, Reciprocal Exchange | $ 29.0 | $ 22.0
Surplus Notes and Guarantee Fund Certificates, Additional Reciprocal Exchange | 7.0 |
Variable Interest Entity, Not Primary Beneficiary |  |
Schedule of Equity Method Investments [Line Items] |  |
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount | $ 17.4 | $ 17.6

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