Additional Working Capital Information (Schedule Of Notes, Accounts Receivable And Payable, Loans Payable, Accrued Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Notes and Accounts Receivable [Abstract]
Trade notes and accounts receivable, less reserves of $61 million and $72 million	$ 19,638	$ 21,274
Other notes and accounts receivable, less reserves of $339 million and $539 million	5,063	4,323
Total notes and accounts receivable	24,701	25,597
Trade notes and accounts receivable, reserves	61	72
Other notes and accounts receivable, reserves	339	539
Notes And Loans Payable [Abstract]
Bank loans	325	115
Commercial paper	12,863	13,049
Long-term debt due within one year	4,070	4,766
Total notes and loans payable	17,258	17,930
Accounts Payable And Accrued Liabilities Current [Abstract]
Trade payables	21,063	21,701
Payables to equity companies	6,863	5,453
Accrued taxes other than income taxes	3,280	3,311
Other accounts payable and accrued liabilities	6,062	6,331
Total accounts payable and accrued liabilities	$ 37,268	$ 36,796