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Reinsurance - Schedule of Disaggregation of Reinsurance Recoverable by Financial Strength Rating and Aging Analysis (Details) - USD ($) $ in Thousands | Sep. 30, 2024 | Jun. 30, 2024 | Dec. 31, 2023 | Sep. 30, 2023 | Jun. 30, 2023 | Dec. 31, 2022
--- | --- | --- | --- | --- | --- | ---
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | $ 1,059,251 |  | $ 658,525 |  |  |
Less: allowance for credit losses | (2,000) | $ (1,700) | (1,700) | $ (1,800) | $ (1,800) | $ (1,600)
Total reinsurance recoverable, net | 1,057,251 |  | 656,825 |  |  |
Reinsurance Recoverable for Paid and Unpaid Claims and Claims Adjustments, Gross | Current |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | 1,057,078 |  | 654,071 |  |  |
Reinsurance Recoverable for Paid and Unpaid Claims and Claims Adjustments, Gross | Past Due |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | 2,173 |  | 4,454 |  |  |
Federal and state pools |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | 325,080 |  | 80,506 |  |  |
Federal and state pools | Current |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | 325,080 |  | 80,506 |  |  |
Federal and state pools | Past Due |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | 0 |  | 0 |  |  |
Other than federal and state pools |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | 4,774 |  | 4,565 |  |  |
Other than federal and state pools | Current |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | 4,679 |  | 4,488 |  |  |
Other than federal and state pools | Past Due |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | 95 |  | 77 |  |  |
Total non-rated reinsurers |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | 329,854 |  | 85,071 |  |  |
Total non-rated reinsurers | Current |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | 329,759 |  | 84,994 |  |  |
Total non-rated reinsurers | Past Due |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | 95 |  | 77 |  |  |
A++ |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | 109,922 |  | 82,487 |  |  |
A++ | Current |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | 109,343 |  | 82,466 |  |  |
A++ | Past Due |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | 579 |  | 21 |  |  |
A+ |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | 476,187 |  | 374,019 |  |  |
A+ | Current |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | 475,190 |  | 371,132 |  |  |
A+ | Past Due |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | 997 |  | 2,887 |  |  |
A |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | 137,607 |  | 113,263 |  |  |
A | Current |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | 137,194 |  | 111,883 |  |  |
A | Past Due |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | 413 |  | 1,380 |  |  |
A- |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | 5,681 |  | 3,685 |  |  |
A- | Current |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | 5,592 |  | 3,596 |  |  |
A- | Past Due |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | 89 |  | 89 |  |  |
Total rated reinsurers |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | 729,397 |  | 573,454 |  |  |
Total rated reinsurers | Current |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | 727,319 |  | 569,077 |  |  |
Total rated reinsurers | Past Due |  |  |  |  |  |
Reinsurance Recoverable, Credit Quality Indicator [Line Items] |  |  |  |  |  |
Total reinsurance recoverable, gross | $ 2,078 |  | $ 4,377 |  |  |

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