Investments (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Schedule of Investments [Line Items]
Impairment (recoveries) losses on investments	$ (0.1)	$ 0.8	$ 0.1	$ 27.9
Mortgage Loans [Member]
Schedule of Investments [Line Items]
Impairment (recoveries) losses on investments	(0.7)		(0.7)	6.6
Allowance for credit losses	7.1		7.1		$ 7.9
Fixed Maturities [Member]
Schedule of Investments [Line Items]
Impairment (recoveries) losses on investments	0.6	$ 0.8	0.8	19.1
Impairments on fixed maturities included intend to sell				16.5
Impairments on fixed maturities credit related losses				$ 2.6
Fixed Maturities Including Held For Sale [Member]
Schedule of Investments [Line Items]
Allowance for credit losses	$ 0.2		$ 0.2		$ 0.1