Earnings Per Share (Earnings Per Share Computation) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings per common share
Net income (loss) attributable to ExxonMobil (millions of dollars)	$ (1,080)	$ 3,130	$ (1,690)	$ 5,480
Weighted average number of common shares outstanding (millions of shares)	4,271	4,271	4,270	4,270
Earnings (Loss) per common share (dollars)	$ (0.26)	$ 0.73	$ (0.40)	$ 1.28
Dividends paid per common share (dollars)	$ 0.87	$ 0.87	$ 1.74	$ 1.69