CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statement of Comprehensive Income [Abstract]
Net Income	$ 1,314.2	$ 824.2	$ 793.0
Other Comprehensive Income (Loss)
Change in Net Unrealized Gain (Loss) on Securities Before Adjustment (net of tax expense (benefit) of $(1,890.8); $(346.9); $250.2)	(7,042.9)	(1,301.4)	983.0
Change in Adjustment to Deferred Acquisition Costs and Reserves for Future Policy and Contract Benefits, Net of Reinsurance (net of tax expense (benefit) of $1,100.8; $316.8; $(138.2))	4,056.9	1,195.9	(531.2)
Change in Net Gain (Loss) on Hedges (net of tax benefit of $19.2; $9.8; $23.8)	(71.4)	(36.0)	(90.0)
Change in Foreign Currency Translation Adjustment (net of tax expense (benefit) of $(0.1); $4.2; $(4.3))	(115.2)	(12.6)	20.3
Change in Unrecognized Pension and Postretirement Benefit Costs (net of tax expense (benefit) of $18.9; $42.1; $(34.8))	(61.9)	(134.0)	45.2
Total Other Comprehensive Income (Loss)	(3,110.7)	(20.1)	336.9
Comprehensive Income (Loss)	$ (1,796.5)	$ 804.1	$ 1,129.9