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Third-Party Reinsurance - Effects of Reinsurance (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Written premiums: |  |  |
Direct | $ 24.1 | $ 58.6 | $ 63.8
Assumed | 31.9 | 0.0 | 1.3
Gross written premiums | 56.0 | 58.6 | 65.1
Earned premiums: |  |  |
Direct | 15.8 | 28.7 | 28.6
Assumed | 15.9 | 2.5 | 4.7
Gross earned premiums | 31.7 | 31.2 | 33.3
Net earned premiums | 1,691.6 | 1,440.9 | 1,076.7
Loss and LAE: |  |  |
Net incurred loss and LAE | 888.5 | 726.8 | 536.4
Ark Insurance Holdings Limited/Outrigger |  |  |
Written premiums: |  |  |
Direct | 1,101.5 | 931.9 | 760.4
Assumed | 1,105.5 | 966.5 | 691.6
Gross written premiums | 2,207.0 | 1,898.4 | 1,452.0
Ceded | (527.9) | (377.5) | (256.8)
Net written premiums | 1,679.1 | 1,520.9 | 1,195.2
Earned premiums: |  |  |
Direct | 1,004.2 | 848.1 | 655.5
Assumed | 1,088.2 | 925.6 | 668.7
Gross earned premiums | 2,092.4 | 1,773.7 | 1,324.2
Ceded | (504.6) | (364.0) | (280.8)
Net earned premiums | 1,587.8 | 1,409.7 | 1,043.4
Loss and LAE: |  |  |
Gross | 1,056.7 | 782.5 | 814.9
Ceded | (200.9) | (55.7) | (278.5)
Net incurred loss and LAE | 855.8 | 726.8 | $ 536.4
Ark Insurance Holdings Limited/Outrigger | Ark Insurance Holdings Limited - Segment |  |  |
Written premiums: |  |  |
Ceded | 86.5 | (110.0) |
Earned premiums: |  |  |
Ceded | 88.0 | 104.3 |
Loss and LAE: |  |  |
Ceded | $ 29.9 | $ 15.6 |

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