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Significant Transactions - Outrigger Re (Details) - USD ($) $ in Millions | 1 Months Ended | 3 Months Ended |
--- | --- | --- | ---
Jan. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022 | Mar. 31, 2024
Outrigger Re |  |  |  |
Other Significant Transactions [Line Items] |  |  |  |
Contributions to subsidiaries |  |  | $ 205.0 |
Outrigger Re |  |  |  |
Other Significant Transactions [Line Items] |  |  |  |
Ceded unearned premiums |  |  | $ 250.0 |
Rollover amount |  | $ 130.0 |  |
Short-term investments, at fair value |  | $ 265.3 |  | $ 222.4
Return of capital | $ 68.1 |  |  |

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