Schedule of Components of Unrealized Gain (Loss) on Securities (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Change in Components of Net Unrealized Gain on Securities
Change in Net Unrealized Gain on Securities	$ (1,267.1)	$ 572.7	$ (916.9)	$ 1,282.7
Fixed Maturity Securities
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	6,826.8	5,150.8	6,261.5	4,054.8
Change in Net Unrealized Gain on Securities	(1,925.6)	865.3	(1,360.3)	1,961.3
End of Period Balance	4,901.2	6,016.1	4,901.2	6,016.1
Other Investments
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	(18.4)	40.6	13.9	55.5
Change in Net Unrealized Gain on Securities	3.6	12.1	(28.7)	(2.8)
End of Period Balance	(14.8)	52.7	(14.8)	52.7
Deferred Acquisition Costs
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	(56.6)	(48.9)	(50.8)	(41.6)
Change in Net Unrealized Gain on Securities	14.8	(5.8)	9.0	(13.1)
End of Period Balance	(41.8)	(54.7)	(41.8)	(54.7)
Reserve for Future Policy and Contract Benefits
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	(6,513.9)	(4,939.7)	(6,150.3)	(4,108.5)
Change in Net Unrealized Gain on Securities	1,532.3	(642.3)	1,168.7	(1,473.5)
End of Period Balance	(4,981.6)	(5,582.0)	(4,981.6)	(5,582.0)
Reinsurance Recoverable
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	387.9	309.9	365.0	263.8
Change in Net Unrealized Gain on Securities	(75.0)	39.6	(52.1)	85.7
End of Period Balance	312.9	349.5	312.9	349.5
Deferred Income Tax
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	(211.5)	(187.4)	(149.0)	(88.3)
Change in Net Unrealized Gain on Securities	147.7	(93.0)	85.2	(192.1)
End of Period Balance	(63.8)	(280.4)	(63.8)	(280.4)
Net Unrealized Gain on Securities
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	414.3	325.3	290.3	135.7
Change in Net Unrealized Gain on Securities	(302.2)	175.9	(178.2)	365.5
End of Period Balance	$ 112.1	$ 501.2	$ 112.1	$ 501.2