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