Investments Investments - Net Realized Gains on Sales of Investments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Fixed Maturities [Member]
Net Investment Income [Line Items]
Gains on Sales	$ 3.6	$ 0.2	$ 9.5	$ 5.0
Losses on Sales	(0.1)	0.0	(0.7)	0.0
Equity Securities [Member]
Net Investment Income [Line Items]
Gains on Sales	2.8	7.9	35.7	11.7
Losses on Sales	$ (0.7)	$ 0.0	$ (1.4)	$ 0.0