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v3.25.0.1

Third-Party Reinsurance - Remaining Gross and Net Reinsurance Recoverables (Details) - USD ($) $ in Millions | 12 Months Ended |  |  |
--- | --- | --- | --- | ---
Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
P&C Insurance and Reinsurance (Ark/WM Outrigger) |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Gross | $ 491.9 |  |  |
Net | 417.4 |  |  |
Reinsurance recoverable on unpaid losses | $ 434.4 | $ 340.8 | $ 505.0 | $ 428.9
P&C Insurance and Reinsurance (Ark/WM Outrigger) | Reinsurance Recoverable Including Reinsurance Premium Paid | Reinsurer Concentration Risk |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
% of Total | 100.00% |  |  |
P&C Insurance and Reinsurance (Ark/WM Outrigger) | Ceded Credit Risk, Secured |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Collateral | $ 74.5 |  |  |
Ark Insurance Holdings Limited/Outrigger |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Collateral | 589.0 | 442.0 |  |
Reinsurance recoverable on unpaid losses | 434.4 | 340.8 |  |
Ark Insurance Holdings Limited/Outrigger | Ark Insurance Holdings Limited - Segment |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Reinsurance recoverable on unpaid losses | (31.8) | $ (15.6) |  |
A+ or better | P&C Insurance and Reinsurance (Ark/WM Outrigger) |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Gross | 310.3 |  |  |
Net | $ 310.3 |  |  |
A+ or better | P&C Insurance and Reinsurance (Ark/WM Outrigger) | Reinsurance Recoverable Including Reinsurance Premium Paid | Reinsurer Concentration Risk |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
% of Total | 74.30% |  |  |
A+ or better | P&C Insurance and Reinsurance (Ark/WM Outrigger) | Ceded Credit Risk, Secured |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Collateral | $ 0.0 |  |  |
A- to A | P&C Insurance and Reinsurance (Ark/WM Outrigger) |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Gross | 98.5 |  |  |
Net | $ 98.5 |  |  |
A- to A | P&C Insurance and Reinsurance (Ark/WM Outrigger) | Reinsurance Recoverable Including Reinsurance Premium Paid | Reinsurer Concentration Risk |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
% of Total | 23.60% |  |  |
A- to A | P&C Insurance and Reinsurance (Ark/WM Outrigger) | Ceded Credit Risk, Secured |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Collateral | $ 0.0 |  |  |
B++ or lower and not rated | P&C Insurance and Reinsurance (Ark/WM Outrigger) |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Gross | 83.1 |  |  |
Net | $ 8.6 |  |  |
B++ or lower and not rated | P&C Insurance and Reinsurance (Ark/WM Outrigger) | Reinsurance Recoverable Including Reinsurance Premium Paid | Reinsurer Concentration Risk |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
% of Total | 2.10% |  |  |
B++ or lower and not rated | P&C Insurance and Reinsurance (Ark/WM Outrigger) | Ceded Credit Risk, Secured |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Collateral | $ 74.5 |  |  |
B++ or lower and not rated | Ark Insurance Holdings Limited/Outrigger | Ark Insurance Holdings Limited - Segment |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Gross | (34.9) |  |  |
Collateral | $ (34.9) |  |  |

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