Contingencies (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		1 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Oct. 31, 2011	Jun. 30, 2007	Oct. 07, 2011	Jan. 22, 2015
Loss Contingencies [Line Items]
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	$ 8.0	$ 0
Esurance
Loss Contingencies [Line Items]
Warranty agreement period			18 months
Non-solicitation agreement period			3 years
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]
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	8.0
OneBeacon Runoff [Member]
Loss Contingencies [Line Items]
Number of insurance holders						3
OneBeacon Runoff [Member] | Segment, Discontinued Operations
Loss Contingencies [Line Items]
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	$ (0.1)	$ (0.5)