Contingencies (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended			12 Months Ended
	Jun. 30, 2007	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 Esurance	Dec. 31, 2011 Esurance	Dec. 31, 2012 Esurance	Dec. 30, 2011 Esurance
Loss Contingencies [Line Items]
Warranty agreement period				18 months
Covenant breach agreement period				2 years
Non-soliciation agreement period				3 years
Percentage of fluctuation in loss reserves of transferred subsidiaries retained						90.00%
Sales of consolidated and unconsolidated affiliates, net of cash sold		$ 31.3	$ 0		$ 1,010.0
Gain on sale of business in discontinued operations					700
Disposal Group Including Discontinued Operation Book Value					308
Total amount in dispute with Allstate							20
DAC amount in dispute with Allstate, Pre-tax							24.7
DAC amount in dispute with Allstate, after-tax							16.0
Extra contractual obligation in dispute with Allstate, pre-tax							5.2
Extra contractual obligation in dispute with Allstate, after-tax							3.4
Proceeds from Sale, Maturity and Collection of Investments	$ 39