Amount after tax of gain (loss) not previously recognized resulting from the disposal of a discontinued operation.

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Name:	us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Held for Sale and Discontinued Operations - (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Discontinued Operations [Line Items}
Net gain from sale of discontinued operations, net of tax	$ 0.9	$ (17.3)	$ 1.6	$ (17.2)
Connecticut \| Discontinued Operations, Held-for-sale
Discontinued Operations [Line Items}
Assets held for sale	2.8		2.8		$ 3.3
Swedish Tax Authority \| Discontinued Operations \| Sirius Group
Discontinued Operations [Line Items}
Net gain from sale of discontinued operations, net of tax				$ 0.1
Sirius Group \| Swedish Tax Authority \| Sirius Group
Discontinued Operations [Line Items}
Contingent liability	$ 15.7		$ 15.7		$ 17.3