CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Investments [Abstract]
Fixed Maturity Securities, Amortized Cost	$ 36,888.0	$ 36,640.7
Stockholders' Equity
Common Stock, Par	$ 0.10	$ 0.10
Common Stock, Authorized	725,000,000	725,000,000
Common Stock, Issued	359,304,646	358,691,567
Treasury Stock, Shares	73,492,245	65,975,613