CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net Income	$ 280.9	$ 273.5
Other Comprehensive Income (Loss)
Change in Net Unrealized Gain on Securities Before Adjustment (net of tax expense (benefit) of $326.8; $(274.9))	1,245.1	(1,042.1)
Change in Adjustment to Deferred Acquisition Costs and Reserves for Future Policy and Contract Benefits, Net of Reinsurance (net of tax expense (benefit) of $(245.5); $212.1)	(932.8)	807.9
Change in Net Gain on Hedges (net of tax benefit of $5.8; $2.3)	(20.5)	(8.8)
Change in Foreign Currency Translation Adjustment (net of tax expense of $0.3; $ -)	17.3	47.5
Change in Unrecognized Pension and Postretirement Benefit Costs (net of tax expense of $0.7; $0.7)	2.8	3.1
Total Other Comprehensive Income (Loss)	311.9	(192.4)
Comprehensive Income	$ 592.8	$ 81.1