Investments (Schedule of Realized Gain (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Fixed Maturities [Member]
Gain (Loss) on Investments [Line Items]
Proceeds from Sales	$ 145.4	$ 594.4	$ 307.9	$ 824.7
Gross Gains	3.5	10.6	5.9	12.9
Gross Losses	0.9	1.4	4.2	4.7
Equity Securities [Member]
Gain (Loss) on Investments [Line Items]
Proceeds from Sales	84.5	83.1	173.4	167.8
Gross Gains	1.7	$ 7.7	26.4	$ 20.1
Gross Losses	$ 0.8		$ 1.7