Derivative Financial Instruments (Effect Of Non-Hedging Derivatives On Income Statement And Included In Net Realized Gains (Losses) On Investments) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Gain (Loss) Recognized	$ (63.3)	$ (52.7)	$ (79.0)
Derivatives Embedded In Convertible Fixed Maturity Securities [Member] | Net Realized Gains (Losses) Investments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Gain (Loss) Recognized	11.6	31.5	(2.4)
Interest Rate Swaps [Member] | Net Realized Gains (Losses) Investments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Gain (Loss) Recognized	(11.6)	2.2
Credit Default And Interest Rate Swaps [Member] | Net Realized Gains (Losses) Investments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Gain (Loss) Recognized			(3.9)
Options [Member] | Net Realized Gains (Losses) Investments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Gain (Loss) Recognized	(54.6)	(111.7)	(66.0)
Futures [Member] | Net Realized Gains (Losses) Investments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Gain (Loss) Recognized	(10.0)	22.3	(6.7)
Swaptions [Member] | Net Realized Gains (Losses) Investments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Gain (Loss) Recognized	$ 1.3	$ 3.0