11. Separate Accounts Death Benefits, Other Insurance Benefit Features and Embedded Product Derivatives (Details 3) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2011
Additional Insurance Benefits	$ 998.0	$ 968.2
Average Attained Age Of Annuitant	63 years	63 years
GMWB
Additional Insurance Benefits	590.6	572.5
Average Attained Age Of Annuitant	63 years	62 years
GMAB
Additional Insurance Benefits	397.2	385.6
Average Attained Age Of Annuitant	58 years	57 years
COMBO
Additional Insurance Benefits	$ 10.2	$ 10.1
Average Attained Age Of Annuitant	61 years	61 years