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Held for Sale and Discontinued Operations - Narrative (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | --- | ---
Sep. 30, 2022 | Sep. 30, 2021 | Sep. 30, 2022 | Sep. 30, 2021 | Dec. 31, 2018 | Dec. 31, 2021 | Dec. 31, 2020
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |
Net gain (loss) from sale of discontinued operations, net of tax - Sirius Group |  |  | $ 886.8 | $ 18.7 |  |  |
Other Operations |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |
Liability related to sale | $ 0.0 |  | 0.0 |  |  | $ 495.3 |
Assets held for sale - Other | 0.0 |  | 0.0 |  |  | $ 16.1 |
Sirius Group |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |
Net gain (loss) from sale of discontinued operations, net of tax - Sirius Group | $ 0.0 | $ 0.0 | $ 0.0 | 18.7 | $ 17.3 |  |
Discontinued Operations, Disposed of by Sale | Sirius Group |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |
Net gain (loss) from sale of discontinued operations, net of tax - Sirius Group |  |  |  | 17.6 |  |  |
Liability related to sale |  |  |  |  |  |  | $ 18.7
Net (income) loss from discontinued operations attributable to non-controlling interests |  |  |  | $ 1.1 |  |  |

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