Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $) In Millions, except Share data	Sep. 30, 2011	Dec. 31, 2010
Consolidated Balance Sheets (Parenthetical) [Abstract]
Common stock, par or stated value per share	$ 1	$ 1
Common stock, shares authorized	1,350,000,000	1,350,000,000
Common stock, shares outstanding, net of treasury shares	336,106,217	357,362,604
Properties, accumulated depreciation	$ 9,351	$ 9,262