Document And Entity Information	3 Months Ended
	Mar. 31, 2020 shares
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2020
Document Fiscal Year Focus	2020
Document Transition Report	false
Entity File Number	1-2256
Entity Registrant Name	Exxon Mobil Corporation
Entity Incorporation, State or Country Code	NJ
Entity Tax Identification Number	13-5409005
Entity Address, Address Line One	5959 Las Colinas Boulevard
Entity Address City or Town	Irving
Entity Address State or Province	TX
Entity Address, Postal Zip Code	75039-2298
City Area Code	972
Local Phone Number	940-6000
Security 12(b) Title	Common Stock, without par value
Trading Symbol	XOM
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding	4,228,211,252
Entity Central Index Key	0000034088
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31