Investing Activities Investment Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2013	Sep. 30, 2013	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Investments, Debt and Equity Securities [Abstract]
Debt securities							$ 135.0	[1]	$ 122.5	[1]	$ 94.8	[1]
Policy loans							2.9		3.1		3.1
Limited partnerships and other investments							1.8		2.2		1.8
Fair value investments							2.6		4.0		2.8
Total investment income							142.3		131.8		102.5
Less: Investment expenses							1.5		0.9		1.4
Net investment income	$ 37.4	$ 36.3	$ 34.1	$ 33.0	$ 67.1	$ 103.4	$ 140.8		$ 130.9		$ 101.1

[1] Includes net investment income on short-term investments.