Investments - Schedule of Other Than Temporary Impairment (Details) - Fixed Maturities [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
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	$ 1.1	$ 1.6
Pre-tax Credit Losses on Fixed Maturities without Pre-tax Credit Losses Included in Cumulative Balance at Beginning of Period	0.1	0.0
Cumulative Balance of Pre-tax Credit Losses Recognized in Retained Earnings at End of Period	$ 1.2	$ 1.6