(Income (Loss) from Discontinued Operations) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Revenues
Earned insurance premiums	$ 536.8	$ 491.1	$ 1,545.3	$ 1,433.5
Net investment income	37.6	42.8	119.8	138.1
Net realized and unrealized investment gains (losses)	72.7	2.9	123.2	36.4
Other revenue	50.3	(35.0)	81.0	(28.3)
Revenues	697.4	501.8	1,869.3	1,579.7
Expenses
Loss and loss adjustment expenses	308.1	280.2	821.7	920.4
Insurance and reinsurance acquisition expenses	107.6	107.0	326.2	296.6
Other underwriting expenses	76.6	64.3	228.4	203.9
General and administrative expenses	58.7	36.2	146.3	120.4
Total expenses	562.3	500.5	1,555.7	1,580.1
Income (loss) from discontinued operations	(15.8)	(12.0)	(24.5)	(7.8)
Gain (loss) on sale of discontinued operation, net of tax	(91.0)	(18.2)	(91.0)	(18.2)
Segment, Discontinued Operations [Member]
Revenues
Earned insurance premiums	(0.4)	233.3	10.0	701.9
Net investment income	0	3.8	0	11.8
Net realized and unrealized investment gains (losses)	0	(6.4)	0	1.4
Other revenue	0	17.5	0	54.0
Revenues	(0.4)	248.2	10.0	769.1
Expenses
Loss and loss adjustment expenses	27.7	177.4	48.4	512.3
Insurance and reinsurance acquisition expenses	(0.8)	51.4	(1.3)	154.1
Other underwriting expenses	(1.1)	35.0	1.1	83.9
General and administrative expenses	0	1.7	0	37.5
Total expenses	25.8	265.5	48.2	787.8
Pre-tax (loss) income	(26.2)	(17.3)	(38.2)	(18.7)
Income tax benefit	10.4	5.3	13.7	10.9
Income (loss) from discontinued operations	(15.8)	(12.0)	(24.5)	(7.8)
Gain (loss) on sale of discontinued operation, net of tax	(91.0)	(18.2)	(91.0)	18.2
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	$ (106.8)	$ (30.2)	$ (115.5)	$ (26.0)