Discontinued Operations (Details) (USD $) In Millions, unless otherwise specified									1 Months Ended
	Jun. 30, 2012	Mar. 31, 2012	Jan. 02, 2012	Dec. 31, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Feb. 22, 2012 AutoOne Entity	Oct. 31, 2011 Esurance	Dec. 31, 2011 Discontinued Operations.
Discontinued Operations
Gain (loss) on sale of discontinued operation, net of tax									$ 677.5
Number of insurance companies sold								2
Assets held for sale
Fixed maturity investments, at fair value	5,248.7			6,221.9						111.8
Total investments	7,224.3			8,268.0
Cash	811.6			705.4						5.5
Insurance premiums receivable	747.0			489.2						8.8
Deferred acquisition costs	200.0		5.6	187.0						2.2
Deferred Income Tax Assets	504.6			536.9						1.9
Other assets	673.0			681.9						2.4
Total assets	13,280.5			14,064.0						132.6
Liabilities held for sale
Loss and loss adjustment expense reserves	5,329.8	5,510.8		5,702.3	5,642.4	5,759.8	5,736.8			64.7
Unearned insurance premiums	1,065.4			846.9						34.1
Other liabilities	461.9			527.8						8.8
Total liabilities	8,946.0			9,396.1						107.6
Net assets held for sale										$ 25.0