Other Comprehensive Income Information (Schedule Of Accumulated Other Comprehensive Income Information) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Other Comprehensive Income Foreign Currency Transaction And Translation Adjustment Net Of Tax Period Increase Decrease [Abstract]
Current period change excluding amounts reclassified from accumulated other comprehensive income, Cumulative Foreign Exchange Translation Adjustment	$ 2,875	$ 600	$ (2,774)	$ 1,349
Other Comprehensive Income Defined Benefit Plans Adjustment Net Of Tax Period Increase Decrease [Abstract]
Current period change excluding amounts reclassified from accumulated other comprehensive income, Postretirement Benefits Reserves Adjustment	(136)	(34)	(49)	(60)
Amounts reclassified from accumulated other comprehensive income, Postretirement Benefits Reserves Adjustment	203	141	407	326
Other Comprehensive Income Loss Net Of Tax Period Change [Abstract]
Beginning Balance, Total			(19,493)
Ending Balance, Total	(21,617)		(21,617)
Exxon Mobil Corporation Share After Noncontrolling Interest [Member]
Other Comprehensive Income Foreign Currency Transaction And Translation Adjustment Net Of Tax Period Increase Decrease [Abstract]
Beginning Balance, Cumulative Foreign Exchange Translation Adjustment			(12,446)	(13,881)
Current period change excluding amounts reclassified from accumulated other comprehensive income, Cumulative Foreign Exchange Translation Adjustment			(2,469)	1,096
Total change in accumulated other comprehensive income, Cumulative Foreign Exchange Translation Adjustment			(2,469)	1,096
Ending Balance, Cumulative Foreign Exchange Translation Adjustment	(14,915)	(12,785)	(14,915)	(12,785)
Net investment hedge gain/(loss), net of taxes			5
Other Comprehensive Income Defined Benefit Plans Adjustment Net Of Tax Period Increase Decrease [Abstract]
Beginning Balance, Postretirement Benefits Reserves Adjustment			(7,047)	(5,683)
Current period change excluding amounts reclassified from accumulated other comprehensive income, Postretirement Benefits Reserves Adjustment			(45)	(49)
Amounts reclassified from accumulated other comprehensive income, Postretirement Benefits Reserves Adjustment			390	312
Total change in accumulated other comprehensive income, Postretirement Benefits Reserves Adjustment			345	263
Ending Balance, Postretirement Benefits Reserves Adjustment	(6,702)	(5,420)	(6,702)	(5,420)
Other Comprehensive Income Loss Net Of Tax Period Change [Abstract]
Beginning Balance, Total			(19,493)	(19,564)
Current period change excluding amounts reclassified from accumulated other comprehensive income, Total			(2,514)	1,047
Amounts reclassified from accumulated other comprehensive income, Total			390	312
Total change in accumulated other comprehensive income, Total			(2,124)	1,359
Ending Balance, Total	$ (21,617)	$ (18,205)	$ (21,617)	$ (18,205)