Contingencies (Details) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Jun. 30, 2007 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jan. 22, 2015	Oct. 07, 2011
Loss Contingencies [Line Items]
Net (loss) income from sale of discontinued operations		$ (0.1)	$ 2.7	$ 7.9	$ 2.7
Esurance
Loss Contingencies [Line Items]
Percentage of fluctuation in loss reserves of transferred subsidiaries retained							90.00%
Tribune Company Litigation | Pending Litigation
Loss Contingencies [Line Items]
Proceeds from Sale, Maturity and Collection of Investments	$ 39.0
Segment, Discontinued Operations
Loss Contingencies [Line Items]
Net (loss) income from sale of discontinued operations		0.1	$ 2.7	8.0	2.7
Gain Contingency, Unrecorded Amount		18.0		$ 18.0
OneBeacon Runoff [Member]
Loss Contingencies [Line Items]
Net (loss) income from sale of discontinued operations		5.3			$ 5.3
Number of insurance holders						3
OneBeacon Runoff [Member] | Segment, Discontinued Operations
Loss Contingencies [Line Items]
Net (loss) income from sale of discontinued operations		$ 0.3