Separate Accounts, Death Benefits and Other Insurance Benefit Features and Embedded Product Derivatives Changes in Additional Liability Balances (Details) (Universal Life, USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Universal Life
Net Amount at Risk by Product and Guarantee [Line Items]
Liability balance, beginning of the period	$ 270.3	$ 302.6	$ 212.0
Incurred	93.2	53.2	35.1
Change due to net unrealized gains or losses included in AOCI	7.6	0.7	15.9
Assumption unlocking	(4.5)	(86.2)	39.6
Liability balance, end of the period	$ 366.6	$ 270.3	$ 302.6