Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	1 Months Ended		9 Months Ended
	Oct. 31, 2015	Oct. 31, 2014	Sep. 30, 2015	Sep. 30, 2014
Decrease (increase) in current assets:
Receivables, net			$ 1,093	$ 503
Inventories			(45)	(1,164)
Income taxes receivable			88	(8)
Prepaid expenses and other			(11)	2
Increase (decrease) in current liabilities:
Accounts payable			(1,007)	(57)
Accrued expenses			(5)	73
Taxes other than income taxes			(50)	(24)
Income taxes payable			(17)	(133)
Changes in current assets and current liabilities			46	(808)
Cash Flows Related to Interest and Income Taxes
Interest paid in excess of amount capitalized			301	271
Income taxes paid, net			1,532	1,209
Supplemental Cash Flow Elements (Textual)
Treasury stock purchased but settled in subsequent quarter			$ 30	$ 70
Stock purchases, in shares		1,500,000
Subsequent Event [Member]
Supplemental Cash Flow Elements (Textual)
Stock purchases, in shares	506,100