Investments - Net Realized Gains on Sales of Investments (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]
Net Investment Income [Line Items]
Realized Gains	$ 4.3	$ 3.9	$ 11.4	$ 5.9
Realized Losses	0.0	0.5	0.3	0.6
Equity Securities [Member]
Net Investment Income [Line Items]
Realized Gains	0.5	31.4	0.5	32.9
Realized Losses	$ 0.1	$ 0.7	$ 0.1	$ 0.7