Schedule of Components of Unrealized Gain (Loss) on Securities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Change in Components of Net Unrealized Gain on Securities
Change in Net Unrealized Gain (Loss) on Securities	$ (1,720.9)	$ 1,439.3	$ (2,101.2)
Fixed Maturity Securities
Change in Components of Net Unrealized Gain on Securities
Beginning of Year Balance	6,261.5	4,054.8	7,221.5
Change in Net Unrealized Gain (Loss) on Securities	(2,565.8)	2,206.7	(3,166.7)
End of Year Balance	3,695.7	6,261.5	4,054.8
Other Investments
Change in Components of Net Unrealized Gain on Securities
Beginning of Year Balance	13.9	55.5	92.8
Change in Net Unrealized Gain (Loss) on Securities	(47.6)	(41.6)	(37.3)
End of Year Balance	(33.7)	13.9	55.5
Deferred Acquisition Costs
Change in Components of Net Unrealized Gain on Securities
Beginning of Year Balance	(50.8)	(41.6)	(67.0)
Change in Net Unrealized Gain (Loss) on Securities	21.4	(9.2)	25.4
End of Year Balance	(29.4)	(50.8)	(41.6)
Reserve for Future Policy and Contract Benefits
Change in Components of Net Unrealized Gain on Securities
Beginning of Year Balance	(6,150.3)	(4,108.5)	(6,277.5)
Change in Net Unrealized Gain (Loss) on Securities	2,571.9	(2,041.8)	2,169.0
End of Year Balance	(3,578.4)	(6,150.3)	(4,108.5)
Reinsurance Recoverable
Change in Components of Net Unrealized Gain on Securities
Beginning of Year Balance	365.0	263.8	351.5
Change in Net Unrealized Gain (Loss) on Securities	(101.8)	101.2	(87.7)
End of Year Balance	263.2	365.0	263.8
Deferred Income Tax Charges
Change in Components of Net Unrealized Gain on Securities
Beginning of Year Balance	(149.0)	(88.3)	(447.8)
Change in Net Unrealized Gain (Loss) on Securities	35.9	(60.7)	359.5
End of Year Balance	(113.1)	(149.0)	(88.3)
Net Unrealized Gain on Securities
Change in Components of Net Unrealized Gain on Securities
Beginning of Year Balance	290.3	135.7	873.5
Change in Net Unrealized Gain (Loss) on Securities	(86.0)	154.6	(737.8)
End of Year Balance	$ 204.3	$ 290.3	$ 135.7