Income from Investments - Net Impairment Losses Recognized in Earnings (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Net Investment Income [Line Items]
Total Other-than-temporary Impairment Losses	$ (11.0)	$ (19.5)	$ (13.8)
Fixed Maturities:
Net Investment Income [Line Items]
Total Other-than-temporary Impairment Losses	(6.4)	(16.7)	(13.3)
Equity Securities
Net Investment Income [Line Items]
Total Other-than-temporary Impairment Losses	(4.2)	$ (2.8)	$ (0.5)
Real Estate
Net Investment Income [Line Items]
Total Other-than-temporary Impairment Losses	$ (0.4)