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Significant Transactions - Outrigger Re (Details) - USD ($) $ in Millions |  |  | 3 Months Ended | 12 Months Ended
--- | --- | --- | --- | ---
Dec. 20, 2022 | Jan. 01, 2021 | Dec. 31, 2022 | Dec. 31, 2022
Ark |  |  |  |
Other Significant Transactions [Line Items] |  |  |  |
Ownership interest after all transactions (as a percent) |  | 72.00% |  |
Outrigger Re |  |  |  |
Other Significant Transactions [Line Items] |  |  |  |
Issuance of redeemable preference shares | $ 250.0 |  |  |
Outrigger Re | Cash and Short Term Investments |  |  |  |
Other Significant Transactions [Line Items] |  |  |  |
Investment owned, balance |  |  | $ 203.7 | $ 203.7
Assets held in trust, expenses |  |  |  | $ 1.3
Outrigger Re |  |  |  |
Other Significant Transactions [Line Items] |  |  |  |
Purchase price |  |  | $ 205.0 |
Ownership interest after all transactions (as a percent) |  |  | 100.00% |

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