Investing Activities Schedule of Unrealized Loss on Investments (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Investments, Debt and Equity Securities [Abstract]
Debt securities	$ (150.5)	$ 123.0	$ 77.2
Equity securities	0	0	0.1
Other investments	0.1	(0.2)	(0.1)
Net unrealized investment gains	(150.4)	122.8	77.2
Net unrealized investment gains	(150.4)	122.8	77.2
Applicable deferred policy acquisition cost	(57.8)	29.2	37.4
Applicable other actuarial offsets	(57.5)	59.9	20.1
Applicable deferred income tax expense (benefit)	(11.8)	24.9	4.2
Offsets to net unrealized investment gains (losses)	(127.1)	114.0	61.7
Net unrealized investment gains included in OCI	$ (23.3)	$ 8.8	$ 15.5