Separate Accounts, Death Benefits and Other Insurance Benefit Features and Embedded Product Derivatives - Changes in Liability Balances (Details) (Universal Life, USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Universal Life
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Balance, beginning of period	$ 318.2	$ 326.0	$ 273.4	$ 300.4
Incurred	16.6	13.3	54.6	45.3
Change due to net unrealized gains or losses included in AOCI	(4.0)	(10.6)	2.8	(17.0)
Assumption unlocking	0	0	0	0
Balance, end of period	$ 330.8	$ 328.7	$ 330.8	$ 328.7