Schedule of Components of Unrealized Gain (Loss) on Securities (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Change in Components of Net Unrealized Gain on Securities
Change in Net Unrealized Gain on Securities	$ (168.5)	$ (152.2)	$ (1,085.4)	$ 1,130.5
Fixed Maturity Securities
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	4,901.2	6,016.1	6,261.5	4,054.8
Change in Net Unrealized Gain on Securities	(237.8)	(221.3)	(1,598.1)	1,740.0
End of Period Balance	4,663.4	5,794.8	4,663.4	5,794.8
Other Investments
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	(14.8)	52.7	13.9	55.5
Change in Net Unrealized Gain on Securities	(20.3)	(22.8)	(49.0)	(25.6)
End of Period Balance	(35.1)	29.9	(35.1)	29.9
Deferred Acquisition Costs
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	(41.8)	(54.7)	(50.8)	(41.6)
Change in Net Unrealized Gain on Securities	1.8	2.4	10.8	(10.7)
End of Period Balance	(40.0)	(52.3)	(40.0)	(52.3)
Reserve for Future Policy and Contract Benefits
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	(4,981.6)	(5,582.0)	(6,150.3)	(4,108.5)
Change in Net Unrealized Gain on Securities	331.9	185.2	1,500.6	(1,288.3)
End of Period Balance	(4,649.7)	(5,396.8)	(4,649.7)	(5,396.8)
Reinsurance Recoverable
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	312.9	349.5	365.0	263.8
Change in Net Unrealized Gain on Securities	(4.8)	(7.4)	(56.9)	78.3
End of Period Balance	308.1	342.1	308.1	342.1
Deferred Income Tax
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	(63.8)	(280.4)	(149.0)	(88.3)
Change in Net Unrealized Gain on Securities	(24.3)	24.7	60.9	(167.4)
End of Period Balance	(88.1)	(255.7)	(88.1)	(255.7)
Net Unrealized Gain on Securities
Change in Components of Net Unrealized Gain on Securities
Beginning of Period Balance	112.1	501.2	290.3	135.7
Change in Net Unrealized Gain on Securities	46.5	(39.2)	(131.7)	326.3
End of Period Balance	$ 158.6	$ 462.0	$ 158.6	$ 462.0