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Held for Sale and Discontinued Operations - Narrative (Details) - Sirius Group - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2018 | Dec. 31, 2020
Discontinued Operations |  |  |  |  |
Net gain (loss) from sale of discontinued operations, net of tax | $ 0.0 | $ 0.0 | $ 18.7 |  |
Discontinued Operations, Disposed of by Sale |  |  |  |  |
Discontinued Operations |  |  |  |  |
Net gain (loss) from sale of discontinued operations, net of tax |  |  | 17.6 | $ (17.3) |
Liabilities held for sale - NSM Group |  |  |  |  | $ 18.7
Net (income) loss from discontinued operations attributable to non-controlling interests |  |  | $ 1.1 |  |

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