Earnings Per Share (Earnings Per Share Computation) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Earnings per common share
Net income (loss) attributable to ExxonMobil		$ (610)	$ 2,350
Weighted average number of common shares outstanding		4,270	4,270
Earnings (Loss) per common share (dollars)	[1]	$ (0.14)	$ 0.55
Dividends paid per common share (dollars)		$ 0.87	$ 0.82

[1] The calculation of earnings (loss) per common share and earnings (loss) per common share – assuming dilution are the same in each period shown.