v3.19.3.a.u2
Document And Entity Information - USD ($)
$ in Billions
 12 Months Ended
Dec. 31, 2019
Jan. 31, 2020
Jun. 28, 2019
Cover [Abstract]      
Document Type 10-K    
Amendment Flag false    
Document Annual Report true    
Document Period End Date Dec. 31, 2019    
Document Fiscal Year Focus 2019    
Document Transition Report false    
Entity File Number 1-2256    
Entity Registrant Name Exxon Mobil Corporation    
Entity Incorporation State Country Code NJ    
Entity Tax Identification Number 13-5409005    
Entity Address Address Line 1 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 Well Known Seasoned Issuer Yes    
Entity Voluntary Filers No    
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 Public Float     $ 324
Entity Common Stock Shares Outstanding   4,232,190,744  
Documents Incorporated By Reference Text Block Proxy Statement for the 2020 Annual Meeting of Shareholders (Part III)    
Document Fiscal Period Focus FY    
Entity Central Index Key 0000034088    
Current Fiscal Year End Date --12-31