CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Net Income	$ 824.2	$ 793.0	$ 1,100.3
Other Comprehensive Income (Loss)
Change in Net Unrealized Gain on Securities Before Adjustment (net of tax expense (benefit) of $(346.9); $250.2; $757.0)	(1,301.4)	983.0	2,870.9
Change in Adjustment to Deferred Acquisition Costs and Reserves for Future Policy and Contract Benefits, Net of Reinsurance (net of tax expense (benefit) of $316.8; $(138.2); $(511.7))	1,195.9	(531.2)	(1,942.6)
Change in Net Gain on Hedges (net of tax benefit of $9.8; $23.8; $17.0)	(36.0)	(90.0)	(62.8)
Change in Foreign Currency Translation Adjustment (net of tax expense (benefit) of $4.2; $(4.3); $0.2)	(12.6)	20.3	23.6
Change in Unrecognized Pension and Postretirement Benefit Costs (net of tax expense (benefit) of $42.1; $(34.8); $(9.3))	(134.0)	45.2	37.6
Total Other Comprehensive Income (Loss)	(20.1)	336.9	851.5
Comprehensive Income	$ 804.1	$ 1,129.9	$ 1,951.8