Derivative Financial Instruments (Details 2) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010
Derivatives, fair value disclosures
Total derivative instruments, assets	$ 1,350.0	$ 1,083.2
Total derivative instruments, liabilities	1,888.9	1,416.9
Fair value of embedded derivative liabilities reported with contractholder funds	166.1	6.6
Interest rate contracts | Derivatives designated as hedging instrument
Derivatives, fair value disclosures
Total derivative instruments, assets	136.3	66.6
Total derivative instruments, liabilities	529.5	405.4
Interest rate contracts | Derivatives not designated as hedging instrument
Derivatives, fair value disclosures
Total derivative instruments, assets	748.4	488.4
Total derivative instruments, liabilities	659.9	459.5
Foreign exchange contracts | Derivatives designated as hedging instrument
Derivatives, fair value disclosures
Total derivative instruments, assets	285.9	390.8
Total derivative instruments, liabilities	155.2	142.5
Foreign exchange contracts | Derivatives not designated as hedging instrument
Derivatives, fair value disclosures
Total derivative instruments, assets	44.8	65.8
Total derivative instruments, liabilities	43.8	60.4
Equity contracts | Derivatives not designated as hedging instrument
Derivatives, fair value disclosures
Total derivative instruments, assets	109.5	64.9
Total derivative instruments, liabilities	0.5	31.7
Credit contracts | Derivatives not designated as hedging instrument
Derivatives, fair value disclosures
Total derivative instruments, assets	25.1	6.7
Total derivative instruments, liabilities	196.0	171.7
Other contracts | Derivatives not designated as hedging instrument
Derivatives, fair value disclosures
Total derivative instruments, liabilities	305.0	145.7
Derivatives designated as hedging instrument
Derivatives, fair value disclosures
Total derivative instruments, assets	422.2	457.4
Total derivative instruments, liabilities	684.7	547.9
Derivatives not designated as hedging instrument
Derivatives, fair value disclosures
Total derivative instruments, assets	927.8	625.8
Total derivative instruments, liabilities	$ 1,205.2	$ 869.0