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Held for Sale and Discontinued Operations - Narrative (Details) £ in Millions, $ in Millions |  | 3 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | --- | ---
Apr. 12, 2021 USD ($) | Apr. 12, 2021 GBP (£) | Mar. 31, 2022 USD ($) | Mar. 31, 2021 USD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |
Net gain from sale of discontinued operations, net of tax |  |  | $ 0.0 | $ 18.7 |  |  |
Loss on sale |  |  |  | 28.7 |  |  |
Total assets |  |  | $ 7,356.7 |  |  | $ 7,000.7 |
Sirius Group |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |
Net gain from sale of discontinued operations, net of tax |  |  |  |  | $ 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 from sale of discontinued operations, net of tax |  |  |  | 17.6 |  |  |
Liability related to sale |  |  |  |  |  |  | $ 18.7
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Fresh Insurance Services Group Limited |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |
Proceeds from sale of business | $ 1.5 | £ 1.1 |  |  |  |  |
Disposal Group, Held-for-sale, Not Discontinued Operations | Fresh Insurance Services Group Limited |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |
Loss on sale |  |  |  | 28.7 |  |  |
Disposal Group, Held-for-sale, Not Discontinued Operations | Other |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |
Total assets |  |  |  | 15.9 |  | $ 16.1 |
Foreign Currency Gain (Loss) | 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 from sale of discontinued operations, net of tax |  |  |  | $ 1.1 |  |  |

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