Reserves for Unpaid Losses and Loss Adjustment Expenses (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended	3 Months Ended	9 Months Ended	0 Months Ended	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011	Sep. 30, 2012 Runoff	Sep. 30, 2012 Runoff	Feb. 22, 2012 AutoOne business	Sep. 30, 2011 AutoOne business		Sep. 30, 2012 AutoOne business		Sep. 30, 2011 AutoOne business
Reserves for Unpaid Loss and LAE
Gross beginning balance	$ 3,175.3	$ 3,131.5	$ 3,358.6	$ 3,295.5	$ 3,295.5
Less beginning reinsurance recoverable on unpaid losses	(2,040.7)	(1,825.9)	(2,167.5)	(1,893.2)	(1,893.2)
Net loss and LAE reserves	1,134.6	1,305.6	1,191.1	1,402.3
Loss and LAE incurred relating to Current year losses	167.0	155.7	460.1	435.7
Loss and LAE incurred relating to Prior year losses	(2.3)	(6.0)	(7.6)	(14.4)
Total incurred loss and LAE from continuing Operations	164.7	149.7	452.5	421.3
Loss and LAE paid relating to Current year losses	(59.6)	(62.2)	(123.0)	(132.9)
Loss and LAE paid relating to Prior year losses	(73.4)	(64.5)	(266.2)	(244.7)
Total loss and LAE payments from continuing operations	(133.0)	(126.7)	(389.2)	(377.6)
Net loss and LAE reserves	1,166.3	1,328.6	1,254.4	1,446.0
Total incurred loss and LAE from discontinued operations	27.7	12.9	48.4	37.7
Total loss and LAE payments from discontinued operations	(67.4)	(63.7)	(177.1)	(205.9)
Net loss and LAE reserves	1,126.6	1,277.8	1,125.7	1,277.8
Net loss and LAE reserves reclassified from (to) held for sale						256.3	256.3	64.7	(58.0)	[1]	64.7	[1]	(58.0)	[1]
Net loss and LAE reserves sold as part of the AutoOne Transaction			(63.8)
Net ending balance	870.3	1,219.8	870.3	1,219.8
Plus ending reinsurance recoverable on unpaid Losses	(41.3)	(1,939.3)	(41.3)	(1,939.3)	(2,167.5)	(1,956.6)	(1,956.6)
Gross ending balance	911.6	3,159.1	911.6	3,159.1	3,358.6	36.7	36.7
Remaining unamortized fair value adjustment			$ 153.4		$ 163.3

[1] In the three and nine months ended September 30, 2011, $58.0 million of net loss and LAE reserves related to the AutoOne Transaction were reclassified to held for sale. For the nine months ended September 30, 2012, $64.7 million of net loss and LAE reserves related to the AutoOne Transaction were reclassified from held for sale upon the closing of the transaction.