Investments - Schedule of Other Than Temporary Impairment (Details) (Fixed Maturities [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Fixed Maturities [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Balance at Beginning of Period	$ 3.6	$ 2.1	$ 3.9	$ 2.4
Reductions to Previously Recognized OTTI Credit Losses	0	(0.2)	(0.1)	(0.5)
Reductions for Investments Sold During Period	0	0	(0.2)	0
Balance at End of Period	$ 3.6	$ 1.9	$ 3.6	$ 1.9