Separate Accounts, Death Benefits and Other Insurance Benefit Features and Embedded Product Derivatives - Non-Insurance Guaranteed Product Features (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Account value	$ 699.2	$ 784.0
Variable Annuity | GMWB
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Account value	$ 427.8	$ 471.3
Average Attained Age of Annuitant	65 years	65 years
Variable Annuity | GMAB
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Account value	$ 266.4	$ 305.8
Average Attained Age of Annuitant	59 years	59 years
Variable Annuity | COMBO
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Account value	$ 5.0	$ 6.9
Average Attained Age of Annuitant	64 years	64 years