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	Jun. 30, 2014	Dec. 31, 2013
Insurance [Abstract]
Debt securities	$ 312.4	$ 322.1
Equity funds	1,450.6	1,538.7
Other	40.9	47.4
Total	$ 1,803.9	$ 1,908.2