CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Net Income	$ 229.9	$ 210.6
Other Comprehensive Income (Loss)
Change in Net Unrealized Gain on Securities Before Adjustment (net of tax expense of $89.0; $414.3)	176.9	800.1
Change in Adjustment to Deferred Acquisition Costs and Reserves for Future Policy and Contract Benefits, Net of Reinsurance (net of tax benefit of $67.3; $287.7)	(134.5)	(566.0)
Change in Net Gain on Cash Flow Hedges (net of tax benefit of $6.0; $13.6)	(10.7)	(26.2)
Change in Foreign Currency Translation Adjustment	17.1	(26.4)
Change in Unrecognized Pension and Postretirement Benefit Costs (net of tax expense of $1.5; $1.6)	2.6	3.1
Total Other Comprehensive Income	51.4	184.6
Comprehensive Income	$ 281.3	$ 395.2