Condensed Consolidated Balance Sheet Parentheticals (USD $) In Millions, except Share data	Sep. 30, 2011	Dec. 31, 2010
Trade accounts receivable, allowances	$ 14	$ 16
Common stock, par value	$ 0.01	$ 0.01
Common stock, authorized	1,100,000,000	1,100,000,000
Common stock, issued	342,549,342	340,561,761
Common stock in treasury, shares	30,532,886	7,995,085