Supplemental Cash Flow Information (Details) - USD ($) $ in Millions			6 Months Ended
		Jan. 01, 2019	Jun. 30, 2019	Jun. 30, 2018
Decrease (increase) in current assets:
Receivables, net			$ (1,664)	$ (595)
Inventories			278	(46)
Prepaid expenses and other			406	(35)
Increase (decrease) in current liabilities:
Accounts payable			1,555	661
Accrued expenses			(195)	(83)
Taxes other than income taxes payable			(75)	28
Income taxes payable			108	(375)
Changes in current assets and current liabilities			413	(445)
Cash Flows Related to Interest and Income Taxes
Interest paid in excess of amount capitalized, including interest on finance leases			227	248
Income taxes paid (received), net			(331)	$ 817
Cash paid for amounts included in the measurement of lease liabilities:
Operating leases - operating cash flows			216
Changes in lease balances resulting from new and modified leases
Operating leases - changes in lease balances resulting from new and modified leases	[1]		1,592
Cash paid for amounts included in the measurement of lease liabilities:
Finance leases - operating cash flows			25
Finance leases - financing cash flows			15
Change in lease balances resulting from new and modified leases
Finance leases - changes in lease balances resulting from new and modified leases			$ 192
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.