Separate Accounts, Death Benefits and Other Insurance Benefit Features and Embedded Product Derivatives - Non-Insurance Guaranteed Product Features(Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended			9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Account Value [Member]	Dec. 31, 2012 Account Value [Member]	Sep. 30, 2013 GMWB	Dec. 31, 2012 GMWB	Sep. 30, 2013 GMAB	Dec. 31, 2012 GMAB	Sep. 30, 2013 COMBO	Dec. 31, 2012 COMBO
Variable Annuity Embedded Derivatives Table [Line Items]
GMWB	$ (0.2)	$ 14.3	$ 553.3	$ 547.4
Average Attained Age of Annuitant	64 years	64 years			64 years	63 years	58 years	58 years	62 years	61 years
GMAB	4.2	14.3	377.3	379.5
COMBO	(0.4)	(0.3)	7.2	8.3
Total variable annuity embedded derivative liabilities	$ 3.6	$ 28.3	$ 937.8	$ 935.2