CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net Income	$ 285.5	$ 245.1	$ 559.0	$ 475.0
Other Comprehensive Income (Loss)
Change in Net Unrealized Gain on Securities Before Adjustment (net of tax expense (benefit) of $(169.5); $206.5; $(444.4); $295.5)	(635.0)	373.3	(1,677.1)	550.2
Change in Adjustment to Deferred Acquisition Costs and Reserves for Future Policy and Contract Benefits, Net of Reinsurance (net of tax expense (benefit) of $133.8; $(162.6); $345.9; $(229.9))	503.4	(298.1)	1,311.3	(432.6)
Change in Net Gain on Hedges (net of tax benefit of $1.6; $6.3; $3.9; $12.3)	(6.7)	(12.3)	(15.5)	(23.0)
Change in Foreign Currency Translation Adjustment (net of tax benefit of $0.3; $-; $0.3; $-)	(61.8)	39.8	(14.3)	56.9
Change in Unrecognized Pension and Postretirement Benefit Costs (net of tax expense of $2.0; $1.3; $2.7; $2.8)	6.3	1.8	9.4	4.4
Total Other Comprehensive Income (Loss)	(193.8)	104.5	(386.2)	155.9
Comprehensive Income	$ 91.7	$ 349.6	$ 172.8	$ 630.9