Separate Accounts, Death Benefits and Other Insurance Benefit Features and Embedded Product Derivatives - Corporate Account Investments of Account Balances of Variable Annuity Contracts with Guarantees (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Insurance [Abstract]
Debt securities	$ 296.0	$ 322.1
Equity funds	1,339.1	1,538.7
Other	38.9	47.4
Total	$ 1,674.0	$ 1,908.2