Schedule of Components of Unrealized Gain (Loss) on Securities (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Change in Components of Net Unrealized Gain on Securities
Change in Net Unrealized Gain (Loss) on Securities	$ (152.2)	$ (151.3)	$ 1,130.5	$ (1,854.9)
Fixed Maturity Securities
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	6,016.1	4,659.6	4,054.8	7,221.5
Change in Net Unrealized Gain (Loss) on Securities	(221.3)	(249.2)	1,740.0	(2,811.1)
End of Period Balance	5,794.8	4,410.4	5,794.8	4,410.4
Other Investments
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	52.7	57.1	55.5	92.8
Change in Net Unrealized Gain (Loss) on Securities	(22.8)	8.1	(25.6)	(27.6)
End of Period Balance	29.9	65.2	29.9	65.2
Deferred Acquisition Costs
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	(54.7)	(43.8)	(41.6)	(67.0)
Change in Net Unrealized Gain (Loss) on Securities	2.4	1.0	(10.7)	24.2
End of Period Balance	(52.3)	(42.8)	(52.3)	(42.8)
Reserve for Future Policy and Contract Benefits
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	(5,582.0)	(4,498.1)	(4,108.5)	(6,277.5)
Change in Net Unrealized Gain (Loss) on Securities	185.2	460.5	(1,288.3)	2,239.9
End of Period Balance	(5,396.8)	(4,037.6)	(5,396.8)	(4,037.6)
Reinsurance Recoverable
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	349.5	283.6	263.8	351.5
Change in Net Unrealized Gain (Loss) on Securities	(7.4)	(8.6)	78.3	(76.5)
End of Period Balance	342.1	275.0	342.1	275.0
Deferred Income Tax
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	(280.4)	(162.8)	(88.3)	(447.8)
Change in Net Unrealized Gain (Loss) on Securities	24.7	(80.0)	(167.4)	205.0
End of Period Balance	(255.7)	(242.8)	(255.7)	(242.8)
Net Unrealized Gain on Securities
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	501.2	295.6	135.7	873.5
Change in Net Unrealized Gain (Loss) on Securities	(39.2)	131.8	326.3	(446.1)
End of Period Balance	$ 462.0	$ 427.4	$ 462.0	$ 427.4