Schedule of Components of Unrealized Gain (Loss) on Securities (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Change in Components of Net Unrealized Gain on Securities
Change in Net Unrealized Gain (Loss) on Securities	$ 572.7	$ (1,425.1)	$ 1,282.7	$ (1,703.6)
Fixed Maturity Securities
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	5,150.8	6,803.9	4,054.8	7,221.5
Change in Net Unrealized Gain (Loss) on Securities	865.3	(2,144.3)	1,961.3	(2,561.9)
End of Period Balance	6,016.1	4,659.6	6,016.1	4,659.6
Other Investments
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	40.6	72.5	55.5	92.8
Change in Net Unrealized Gain (Loss) on Securities	12.1	(15.4)	(2.8)	(35.7)
End of Period Balance	52.7	57.1	52.7	57.1
Deferred Acquisition Costs
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	(48.9)	(61.2)	(41.6)	(67.0)
Change in Net Unrealized Gain (Loss) on Securities	(5.8)	17.4	(13.1)	23.2
End of Period Balance	(54.7)	(43.8)	(54.7)	(43.8)
Reserve for Future Policy and Contract Benefits
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	(4,939.7)	(5,979.7)	(4,108.5)	(6,277.5)
Change in Net Unrealized Gain (Loss) on Securities	(642.3)	1,481.6	(1,473.5)	1,779.4
End of Period Balance	(5,582.0)	(4,498.1)	(5,582.0)	(4,498.1)
Reinsurance Recoverable
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	309.9	353.9	263.8	351.5
Change in Net Unrealized Gain (Loss) on Securities	39.6	(70.3)	85.7	(67.9)
End of Period Balance	349.5	283.6	349.5	283.6
Deferred Income Tax
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	(187.4)	(397.0)	(88.3)	(447.8)
Change in Net Unrealized Gain (Loss) on Securities	(93.0)	234.2	(192.1)	285.0
End of Period Balance	(280.4)	(162.8)	(280.4)	(162.8)
Net Unrealized Gain on Securities
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	325.3	792.4	135.7	873.5
Change in Net Unrealized Gain (Loss) on Securities	175.9	(496.8)	365.5	(577.9)
End of Period Balance	$ 501.2	$ 295.6	$ 501.2	$ 295.6