CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net Income	$ 161.0	$ 280.9
Other Comprehensive Income (Loss)
Change in Net Unrealized Gain on Securities Before Adjustment (net of tax expense (benefit) of $(436.5); $326.8)	(1,666.7)	1,245.1
Change in Adjustment to Deferred Acquisition Costs and Reserves for Future Policy and Contract Benefits, Net of Reinsurance (net of tax expense (benefit) of $380.8; $(245.5))	1,446.1	(932.8)
Change in Net Gain on Hedges (net of tax expense (benefit) of $6.6; $(5.8))	22.8	(20.5)
Change in Foreign Currency Translation Adjustment (net of tax expense of $2.1; $0.3)	(63.6)	17.3
Change in Unrecognized Pension and Postretirement Benefit Costs (net of tax expense of $1.9; $0.7)	(7.0)	(2.8)
Total Other Comprehensive Income (Loss)	(254.4)	311.9
Comprehensive Income	$ (93.4)	$ 592.8