Derivative Financial Instruments Notional and Fair Values (Details) (USD $) In Millions, unless otherwise specified						3 Months Ended		9 Months Ended
	Sep. 30, 2012	Jun. 30, 2012		Dec. 31, 2011		Sep. 30, 2012 Non-Qualifying for hedge accounting	Sep. 30, 2011 Non-Qualifying for hedge accounting	Sep. 30, 2012 Non-Qualifying for hedge accounting	Sep. 30, 2011 Non-Qualifying for hedge accounting	Sep. 30, 2012 Interest rate contracts Non-Qualifying for hedge accounting	Dec. 31, 2011 Interest rate contracts Non-Qualifying for hedge accounting	Sep. 30, 2012 Interest rate contracts Non-Qualifying for hedge accounting Derivatives	Dec. 31, 2011 Interest rate contracts Non-Qualifying for hedge accounting Derivatives	Sep. 30, 2012 Foreign exchange contracts Non-Qualifying for hedge accounting	Dec. 31, 2011 Foreign exchange contracts Non-Qualifying for hedge accounting	Sep. 30, 2012 Foreign exchange contracts Non-Qualifying for hedge accounting Derivatives	Dec. 31, 2011 Foreign exchange contracts Non-Qualifying for hedge accounting Derivatives	Sep. 30, 2012 Equity contracts Non-Qualifying for hedge accounting	Dec. 31, 2011 Equity contracts Non-Qualifying for hedge accounting	Sep. 30, 2012 Equity contracts Non-Qualifying for hedge accounting Derivatives	Dec. 31, 2011 Equity contracts Non-Qualifying for hedge accounting Derivatives	Sep. 30, 2012 Credit contracts Non-Qualifying for hedge accounting	Jun. 30, 2012 Credit contracts Non-Qualifying for hedge accounting	Dec. 31, 2011 Credit contracts Non-Qualifying for hedge accounting	Sep. 30, 2012 Credit contracts Non-Qualifying for hedge accounting Derivatives	Dec. 31, 2011 Credit contracts Non-Qualifying for hedge accounting Derivatives	Sep. 30, 2012 Fixed maturities Non-Qualifying for hedge accounting	Dec. 31, 2011 Fixed maturities Non-Qualifying for hedge accounting	Sep. 30, 2012 Within retail annuity products Non-Qualifying for hedge accounting Future policy benefits and claims reserves	Dec. 31, 2011 Within retail annuity products Non-Qualifying for hedge accounting Future policy benefits and claims reserves	Sep. 30, 2012 Within reinsurance agreement Non-Qualifying for hedge accounting Funds held under reinsurance treaties with affiliates	Dec. 31, 2011 Within reinsurance agreement Non-Qualifying for hedge accounting Funds held under reinsurance treaties with affiliates
Derivatives, Fair Value [Line Items]
Net realized gains (losses) on derivatives						$ (307.6)	$ 832.1	$ (1,259.4)	$ 440.3
Derivative, Notional Amount										27,824.8	27,046.0			1,422.8	1,297.8			15,156.8	15,434.3			71.0		143.4
Derivatives	1,628.8			1,609.1								1,465.7	1,538.4			15.0	9.7			147.6	60.1				0.5	0.9
Derivatives	641.9			604.9								572.6	520.0			39.7	42.4			29.5	28.4				0.1	14.1
Embedded Derivatives		51.1	[1]	55.0	[1]																						51.1	55.0	0	0	0	0
Embedded derivative on reinsurance																											0	0	3,349.7	3,512.1	317.7	230.9
Total Derivative Assets, Gross	1,679.9			1,664.1
Total Derivative Liabilities, Gross	4,309.3			4,347.9
Maximum Potential Future Exposure on Credit Risk Derivatives																							$ 70.5	$ 108.8

[1] Embedded derivatives within fixed maturity securities are reported with the host investment. The changes in fair value of embedded derivatives are reported in Other net realized capital gains (losses) in the Condensed Statements of Operations.