Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Decrease (increase) in current assets:
Receivables, net		$ (1,531)	$ 1,294	$ 2,753
Inventories		771	(222)	(1,014)
Income taxes receivable		156	(104)	(23)
Prepaid expenses and other		(109)	(45)	(32)
Increase (decrease) in current liabilities:
Accounts payable		1,556	(1,787)	(3,149)
Accrued expenses		117	(40)	38
Taxes other than income taxes		82	(74)	(64)
Income taxes payable		(66)	(328)	(319)
Changes in current assets and current liabilities		976	(1,306)	(1,810)
Supplemental Cash Flow Elements [Textual]
Stock purchases, in shares	347,438
Payment of long-term liability to joint venture partner		184	(25)	(49)
Cash Flows Related to Interest and Income Taxes
Interest paid in excess of amount capitalized		427	416	392
Income taxes paid, net		444	$ 2,093	$ 1,624
Owner-Method Joint Venture Investment [Member]
Supplemental Cash Flow Elements [Textual]
Payment of long-term liability to joint venture partner		$ 137