Schedule of Components of Unrealized Gain (Loss) on Securities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Change in Components of Net Unrealized Gain on Securities
Change in Net Unrealized Gain on Securities	$ (1,301.4)	$ 983.0	$ 2,870.9
Fixed Maturity Securities
Change in Components of Net Unrealized Gain on Securities
Beginning of Year Balance	7,597.6	6,364.4	2,736.5
Change in Net Unrealized Gain on Securities	(1,648.3)	1,233.2	3,627.9
End of Year Balance	5,949.3	7,597.6	6,364.4
Deferred Acquisition Costs
Change in Components of Net Unrealized Gain on Securities
Beginning of Year Balance	(85.1)	(62.7)	(27.9)
Change in Net Unrealized Gain on Securities	14.7	(22.4)	(34.8)
End of Year Balance	(70.4)	(85.1)	(62.7)
Reserve for Future Policy and Contract Benefits
Change in Components of Net Unrealized Gain on Securities
Beginning of Year Balance	(6,225.6)	(5,803.1)	(3,220.3)
Change in Net Unrealized Gain on Securities	1,566.1	(422.5)	(2,582.8)
End of Year Balance	(4,659.5)	(6,225.6)	(5,803.1)
Reinsurance Recoverable
Change in Components of Net Unrealized Gain on Securities
Beginning of Year Balance	200.2	424.7	261.4
Change in Net Unrealized Gain on Securities	(68.1)	(224.5)	163.3
End of Year Balance	132.1	200.2	424.7
Income Tax
Change in Components of Net Unrealized Gain on Securities
Beginning of Year Balance	(419.4)	(307.4)	(62.1)
Change in Net Unrealized Gain on Securities	30.1	(112.0)	(245.3)
End of Year Balance	(389.3)	(419.4)	(307.4)
Net Unrealized Gain (Loss) on Securities
Change in Components of Net Unrealized Gain on Securities
Beginning of Year Balance	1,067.7	615.9	(312.4)
Change in Net Unrealized Gain on Securities	(105.5)	451.8	928.3
End of Year Balance	$ 962.2	$ 1,067.7	$ 615.9