Information Relating to the Consolidated Statement of Cash Flows - Summary of Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Distributions more (less) than income from equity affiliates includes the following:
Distributions from equity affiliates	$ 1,543	$ 1,895	$ 2,747
(Income) loss from equity affiliates	472	(3,968)	(6,327)
Distributions more (less) than income from equity affiliates	2,015	(2,073)	(3,580)
Net decrease (increase) in operating working capital was composed of the following:
Decrease (increase) in accounts and notes receivable	2,423	1,852	437
Decrease (increase) in inventories	284	7	(424)
Decrease (increase) in prepaid expenses and other current assets	(87)	(323)	(149)
Increase (decrease) in accounts payable and accrued liabilities	(3,576)	(109)	(494)
Increase (decrease) in income and other taxes payable	(696)	67	(88)
Net decrease (increase) in operating working capital	(1,652)	1,494	(718)
Net cash provided by operating activities includes the following cash payments:
Interest on debt (net of capitalized interest)	720	810	736
Income taxes	2,987	4,817	4,748
Proceeds and deposits related to asset sales and returns of investment consisted of the following gross amounts:
Proceeds and deposits related to asset sales	2,891	2,809	2,000
Returns of investment from equity affiliates	77	142	392
Proceeds and deposits related to asset sales and returns of investment	2,968	2,951	2,392
Net maturities (investments) of time deposits consisted of the following gross amounts:
Investments in time deposits	0	0	(950)
Maturities of time deposits	0	950	0
Net maturities of (investments in) time deposits	0	950	(950)
Net sales (purchases) of marketable securities consisted of the following gross amounts:
Marketable securities purchased	0	(1)	(51)
Marketable securities sold	35	3	0
Net sales (purchases) of marketable securities	35	2	(51)
Net repayment (borrowing) of loans by equity affiliates:
Borrowing of loans by equity affiliates	(3,925)	(1,350)	0
Repayment of loans by equity affiliates	2,506	105	111
Net repayment (borrowing) of loans by equity affiliates	(1,419)	(1,245)	111
Net borrowings (repayments) of short-term obligations consisted of the following gross and net amounts:
Proceeds from issuances of short-term obligations	10,846	2,586	2,486
Repayments of short-term obligations	(9,771)	(1,430)	(4,136)
Net borrowings (repayments) of short-term obligations with three months or less maturity	(424)	(3,977)	3,671
Net borrowings (repayments) of short-term obligations	651	(2,821)	2,021
Capital expenditures
Additions to properties, plant and equipment	8,492	13,839	13,384
Additions to investments	136	140	65
Current-year dry hole expenditures	327	124	344
Payments for other liabilities and assets, net	(33)	13	(1)
Capital expenditures	8,922	14,116	13,792
Expensed exploration expenditures	500	598	523
Assets acquired through finance leases and other obligations	53	181	75
Payments for other assets and liabilities, net	42	(13)	0
Capital and exploratory expenditures, excluding equity affiliates	9,517	14,882	14,390
Company’s share of expenditures by equity affiliates	3,982	6,112	5,716
Capital and exploratory expenditures, including equity affiliates	13,499	20,994	20,106
Net sales (purchases) of treasury shares consists of the following gross and net amounts:
Shares issued for share-based compensation plans	226	1,104	1,147
Shares purchased under share repurchase and deferred compensation plans	(1,757)	(4,039)	(1,751)
Net sales (purchases) of treasury shares	(1,531)	(2,935)	(604)
Non-cash additions to properties, plant and equipment	$ 816		$ 25
Non-cash additions to properties, plant and equipment		$ (239)