Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Consolidated Balance Sheets [Abstract]
Common stock, shares authorized	250	250
Common stock, par value	$ 1	$ 1
Common stock , shares issued	104.1	104.1
Common stock share outstanding	93.5	92.6
Unvested restricted common stock included in shares issued and outstanding	0.5	0.6