CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Accounts and notes receivable, allowance for doubtful accounts	$ 87	$ 72
Preferred stock, par value (in usd per share)	$ 0.01	$ 0.01
Preferred stock, authorized (in shares)	25,000,000	25,000,000
Preferred stock, outstanding (in shares)	0	0
Common stock, par value (in usd per share)	$ 0.01	$ 0.01
Common stock, authorized (in shares)	6,000,000,000	6,000,000,000
Common stock, issued (in shares)	1,939,000,000	1,985,000,000
Common stock, outstanding (in shares)	1,939,000,000	1,985,000,000