(Income (Loss) from Discontinued Operations) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Revenues
Earned insurance premiums	$ 495.4	$ 498.0
Net investment income	28.5	41.8
Net realized and unrealized investment gains (losses)	75.2	58.6
Other revenue	28.3	31.2
Total revenues	627.4	629.6
Expenses
Loss and loss adjustment expenses	244.3	249.8
Insurance and reinsurance acquisition expenses	98.2	109.1
Other underwriting expenses	79.1	73.5
General and administrative expenses	43.8	45.5
Total expenses	475.6	488.8
Income (loss) from discontinued operations	0.5	(9.3)
Segment, Discontinued Operations
Revenues
Earned insurance premiums	0.9	8.8
Net investment income	0	0
Net realized and unrealized investment gains (losses)	0	0
Other revenue	0	0
Total revenues	0.9	8.8
Expenses
Loss and loss adjustment expenses	0	19.6
Insurance and reinsurance acquisition expenses	0.1	0.3
Other underwriting expenses	0.1	1.5
General and administrative expenses	0	0
Total expenses	0.2	21.4
Pre-tax income (loss)	0.7	(12.6)
Income tax (expense) benefit	(0.2)	3.3
Income (loss) from discontinued operations	0.5	(9.3)
Loss from sale of discontinued operations	0	0
Net income (loss) from discontinued operations	$ 0.5	$ (9.3)