CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net Income	$ 328.6	$ 231.1	$ 664.5	$ 657.6
Other Comprehensive Income (Loss)
Change in Net Unrealized Gain on Securities Before Adjustment (net of tax expense (benefit) of $(69.0); $126.6; $(276.3); $344.0)	(260.8)	481.4	(1,048.0)	1,322.4
Change in Adjustment to Deferred Acquisition Costs and Reserves for Future Policy and Contract Benefits, Net of Reinsurance (net of tax expense (benefit) of $49.5; $(89.9); $215.5; $(219.7))	185.4	(340.0)	816.3	(833.8)
Change in Net Gain on Hedges (net of tax benefit of $2.2; $6.7; $7.6; $7.2)	(8.0)	(27.5)	(28.3)	(29.1)
Change in Foreign Currency Translation Adjustment (net of tax expense (benefit) of $1.8; $(1.9); $3.4; $(1.1))	(30.5)	34.5	(13.9)	(32.1)
Change in Unrecognized Pension and Postretirement Benefit Costs (net of tax expense of $1.8; $0.4; $4.2; $3.4)	(5.7)	(2.0)	(13.6)	(12.9)
Net Other Comprehensive Income (Loss)	(108.2)	150.4	(260.3)	440.3
Comprehensive Income	$ 220.4	$ 381.5	$ 404.2	$ 1,097.9