Income from Investments - Net Impairment Losses Recognized in Earnings (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Net Investment Income [Line Items]
Total Other-than-temporary Impairment Losses	$ (25.8)	$ (11.0)	$ (19.5)
Fixed Maturities:
Net Investment Income [Line Items]
Total Other-than-temporary Impairment Losses	(25.8)	(6.4)	(16.7)
Equity Securities
Net Investment Income [Line Items]
Total Other-than-temporary Impairment Losses	0.0	(4.2)	(2.8)
Real Estate
Net Investment Income [Line Items]
Total Other-than-temporary Impairment Losses	$ 0.0	$ (0.4)	$ 0.0