Miscellaneous Financial Information (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2020
Disclosure Text Block Supplement [Abstract]
Inventory credit, consolidated companies including noncontrolling interests - before tax	$ 153
Inventory credit, ExxonMobil share including equity companies - after tax	$ 113
After-tax impairment charges		$ 884
Goodwill impairment		562
Other impairment charges		$ 322

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of loss from reductions in inventory due to subsequent measurement adjustments, including, but not limited to, physical deterioration, obsolescence, or changes in price levels.

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The charge against earnings resulting from the write down of long lived assets other than goodwill due to the difference between the carrying value and lower fair value.

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