Discontinued Operations (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Revenues
Earned insurance premiums									$ 1,927.8	$ 2,251.8	$ 2,717.6
Net investment income									184.5	208.9	250.1
Net realized and unrealized investment gains									122.8	82.6	361.7
Other revenue									(57.0)	23.4	113.9
Total revenues	593.6	501.3	553.6	529.6	552.8	551.0	670.8	792.1	2,178.1	2,566.7	3,443.3
Expenses
Loss and loss adjustment expenses									1,206.9	1,389.2	1,424.1
Insurance and reinsurance acquisition expenses									400.0	479.1	547.2
Other underwriting expenses									279.1	332.9	406.6
General and administrative expenses									175.3	155.1	197.4
Total expenses	535.6	500.1	517.5	563.3	457.2	475.8	664.9	815.7	2,116.5	2,413.6	2,646.1
Loss from discontinued operations	674.2	(30.1)	(1.5)	2.5	(7.8)	3.6	0.6	(3.0)	(13.0)	(6.6)	(27.8)
Discontinued Operations.
Revenues
Earned insurance premiums									727.9	910.6	882.8
Net investment income									12.0	19.6	22.3
Net realized and unrealized investment gains									0.7	13.3	22.9
Other revenue									53.5	60.9	55.2
Total revenues									794.1	1,004.4	983.2
Expenses
Loss and loss adjustment expenses									542.3	678.8	695.0
Insurance and reinsurance acquisition expenses									159.2	191.7	170.1
Other underwriting expenses									80.4	87.9	98.7
General and administrative expenses									38.3	48.6	52.6
Total expenses									820.2	1,007.0	1,016.4
Pre-tax (loss)									(26.1)	(2.6)	(33.2)
Income tax benefit (expense)									13.1	(4.0)	5.4
Loss from discontinued operations									645.3	(6.6)	(27.8)
Discontinued Operations. | Esurance
Expenses
Loss from discontinued operations									677.5
Discontinued Operations. | AutoOne
Expenses
Loss from discontinued operations									$ (19.2)