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Commitments and Contingencies (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2021 | Mar. 31, 2021 | Jun. 30, 2020 | Jun. 30, 2021 | Jun. 30, 2020
Loss Contingencies [Line Items] |  |  |  |  |
Net gain from sale of discontinued operations, net of tax | $ 0.0 |  | $ (1.0) | $ 18.7 | $ (0.1)
Sirius Group | Discontinued Operations |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |
Net gain from sale of discontinued operations, net of tax |  | $ 17.6 |  |  |

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