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Reserves for Losses and Adjustment Expenses - Additional Information (Details) - USD ($) $ in Millions | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2024 | Sep. 30, 2023 | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Insurance [Abstract] |  |  |  |  |
Provision for losses and LAE for claims incurred | $ 39.7 | $ 10.5 | $ 60.8 | $ 28.1 | $ 45.1
Financial Guarantee Insurance Contracts, Premium Received over Contract Period [Line Items] |  |  |  |  |
Prior years | 39.7 | 10.5 | $ 60.8 | $ 28.1 | $ 45.1
Reinsurance |  |  |  |  |
Insurance [Abstract] |  |  |  |  |
Provision for losses and LAE for claims incurred | 21.5 | (28.3) |  |  |
Financial Guarantee Insurance Contracts, Premium Received over Contract Period [Line Items] |  |  |  |  |
Prior years | 21.5 | (28.3) |  |  |
Insurance |  |  |  |  |
Insurance [Abstract] |  |  |  |  |
Provision for losses and LAE for claims incurred | 18.2 | 38.8 |  |  |
Financial Guarantee Insurance Contracts, Premium Received over Contract Period [Line Items] |  |  |  |  |
Prior years | $ 18.2 | $ 38.8 |  |  |

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- Definition Amount, after effects of reinsurance, of expense (reversal of expense) for claims incurred in prior reporting periods and related claims settlement costs. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480081/944-40-50-3 + Details
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