CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net Income	$ 281.2	$ 285.5	$ 562.1	$ 559.0
Other Comprehensive Income (Loss)
Change in Net Unrealized Gain on Securities Before Adjustment (net of tax expense (benefit) of $279.3; $(169.5); $606.1; $(444.4))	1,047.7	(635.0)	2,292.8	(1,677.1)
Change in Adjustment to Deferred Acquisition Costs and Reserves for Future Policy and Contract Benefits, Net of Reinsurance (net of tax expense (benefit) of $(201.2); $133.8; $(446.7); $345.9)	(760.7)	503.4	(1,693.5)	1,311.3
Change in Net Gain on Hedges (net of tax benefit of $2.8; $1.6; $8.6; $3.9)	(12.1)	(6.7)	(32.6)	(15.5)
Change in Foreign Currency Translation Adjustment (net of tax expense (benefit) of $0.1; $(0.3); $0.4; $(0.3))	(19.7)	(61.8)	(2.4)	(14.3)
Change in Unrecognized Pension and Postretirement Benefit Costs (net of tax expense of $1.3; $2.0; $2.0; $2.7)	4.6	6.3	7.4	9.4
Total Other Comprehensive Income (Loss)	259.8	(193.8)	571.7	(386.2)
Comprehensive Income	$ 541.0	$ 91.7	$ 1,133.8	$ 172.8