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Commitments and Contingencies (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Loss Contingencies [Line Items]
Net gain from sale of discontinued operations, net of tax	$ (1.0)	$ 0.0	$ (0.1)	$ 0.7
Sirius Group \| Swedish Tax Authority \| Sirius Group
Loss Contingencies [Line Items]
Contingent liability	16.5		$ 16.5		$ 16.5
Change in contingent liability	$ (1.0)