Receivables (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014
Receivables
Accounts receivable				$ 4,105	$ 5,509
Commodity derivative and foreign currency contract receivables				147	151
Other receivables				247	256
Receivables, gross				4,499	5,916
Allowance for doubtful accounts	$ (37)	$ (46)	$ (56)	(35)	(37)
Receivables, net				$ 4,464	$ 5,879
Allowance for Doubtful Accounts Rollforward
Balance as of beginning of year	37	46	56
Increase in allowance charged to expense	7	7	13
Accounts charged against the allowance, net of recoveries	(9)	(15)	(23)
Foreign currency translation	0	(1)	0
Balance as of end of year	$ 35	$ 37	$ 46