Supplemental Cash Flow Information (Details) - USD ($) $ in Millions			9 Months Ended
		Jan. 01, 2019	Sep. 30, 2019	Sep. 30, 2018
Decrease (increase) in current assets:
Receivables, net			$ (669)	$ (1,307)
Inventories			126	(1,134)
Prepaid expenses and other			373	(65)
Increase (decrease) in current liabilities:
Accounts payable			914	1,890
Accrued expenses			(92)	(168)
Taxes other than income taxes payable			(25)	(32)
Income taxes payable			101	(358)
Changes in current assets and current liabilities			728	(1,174)
Cash Flows Related to Interest and Income Taxes
Interest paid in excess of amount capitalized, including interest on finance leases			303	344
Income taxes paid (received), net			(184)	$ 1,116
Cash paid for amounts included in the measurement of lease liabilities:
Operating leases - operating cash flows			329
Operating leases - investing cash flows			1
Changes in lease balances resulting from new and modified leases
Operating leases - changes in lease balances resulting from new and modified leases	[1]		1,673
Cash paid for amounts included in the measurement of lease liabilities:
Finance leases - operating cash flows			38
Finance leases - financing cash flows			24
Change in lease balances resulting from new and modified leases
Finance leases - changes in lease balances resulting from new and modified leases			$ 221
Topic 842 [Member]
Changes in lease balances resulting from new and modified leases
Operating leases - changes in lease balances resulting from new and modified leases		$ 1,300

[1] Includes noncash activity of $1.3 billion for ROU assets for operating leases recorded on January 1, 2019 upon adoption of Topic 842.