Investments - Schedule of Other Than Temporary Impairment (Details) - Fixed Maturities [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Cumulative Balance of Pre-tax Credit Losses Recognized in Retained Earnings at Beginning of Period	$ 1.4	$ 5.1
Pre-tax Credit Losses on Fixed Maturities without Pre-tax Credit Losses Included in Cumulative Balance at Beginning of Period	0.4	2.7
From Status of Credit Loss to Status of Intent-to-sell or Required-to-sell	0.0	(3.6)
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Reductions, Securities Sold	(0.2)	0.0
Cumulative Balance of Pre-tax Credit Losses Recognized in Retained Earnings at End of Period	$ 1.6	$ 4.2