Condensed Consolidated Balance Sheets Parenthetical (USD $) In Millions, except Share data, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Fixed maturities, amortized cost	$ 18,937.1	$ 19,096.7
Equity securities, cost	107.5	119.4
Mortgage loans on real estate valuation allowance	1.2	1.2
Securities pledged, amortized costs	$ 223.1	$ 137.9
Common stock, par value	$ 50	$ 50
Common stock, shares authorized	100,000	100,000
Common stock, shares issued	55,000	55,000
Common stock, shares outstanding	55,000	55,000