Income From Investments - Net Impairment Losses Recognized in Earnings (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net Investment Income [Line Items]
Net Impairment Losses Recognized in Earnings	$ (7.6)	$ (3.4)	$ (1.0)	$ (1.9)	$ (2.8)	$ (3.2)	$ (0.4)	$ (0.5)	$ (13.9)	$ (6.9)	$ (11.3)
Fixed Maturities [Member]
Net Investment Income [Line Items]
Net Impairment Losses Recognized in Earnings									(10.3)	(1.9)	(2.2)
Equity Securities [Member]
Net Investment Income [Line Items]
Net Impairment Losses Recognized in Earnings									(3.6)	(1.9)	(1.9)
Real Estate [Member]
Net Investment Income [Line Items]
Net Impairment Losses Recognized in Earnings									$ 0	$ (3.1)	$ (7.2)