Derivative Financial Instruments (Effect Of Non-Hedging Derivatives On Income Statement And Included In Net Realized Gains (Losses) On Investments) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Gain (Loss) Recognized	$ 10.4	$ (63.3)	$ (52.7)
Derivatives Embedded In Convertible Fixed Maturity Securities [Member] | Net Realized Gains (Losses) Investments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Gain (Loss) Recognized	(22.2)	11.6	31.5
Interest Rate Swaps [Member] | Net Realized Gains (Losses) Investments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Gain (Loss) Recognized	(1.9)	(11.6)	2.2
Options [Member] | Net Realized Gains (Losses) Investments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Gain (Loss) Recognized	34.7	(54.6)	(111.7)
Futures [Member] | Net Realized Gains (Losses) Investments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Gain (Loss) Recognized	(0.1)	(10.0)	22.3
Swaptions [Member] | Net Realized Gains (Losses) Investments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Gain (Loss) Recognized	$ (0.1)	$ 1.3	$ 3.0