v3.19.3.a.u2
Other Comprehensive Income Information (Schedule of Accumulated Other Comprehensive Income Information) (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
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 $ 1,735 $ (5,077) $ 5,352
Amounts reclassified from accumulated other comprehensive income, Cumulative Foreign Exchange Translation Adjustment   196 234
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 (2,092) 280 (219)
Amounts reclassified from accumulated other comprehensive income, Postretirement Benefits Reserves Adjustment 582 931 1,165
Other Comprehensive Income Loss Net Of Tax Period Change [Abstract]      
Beginning Balance, Total (19,564)    
Ending Balance, Total (19,493) (19,564)  
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 (13,881) (9,482) (14,501)
Current period change excluding amounts reclassified from accumulated other comprehensive income, Cumulative Foreign Exchange Translation Adjustment 1,435 (4,595) 4,879
Amounts reclassified from accumulated other comprehensive income, Cumulative Foreign Exchange Translation Adjustment   196 140
Total change in accumulated other comprehensive income, Cumulative Foreign Exchange Translation Adjustment 1,435 (4,399) 5,019
Ending Balance, Cumulative Foreign Exchange Translation Adjustment (12,446) (13,881) (9,482)
Other Comprehensive Income Defined Benefit Plans Adjustment Net Of Tax Period Increase Decrease [Abstract]      
Beginning Balance, Postretirement Benefits Reserves Adjustment (5,683) (6,780) (7,738)
Current period change excluding amounts reclassified from accumulated other comprehensive income, Postretirement Benefits Reserves Adjustment (1,927) 201 (170)
Amounts reclassified from accumulated other comprehensive income, Postretirement Benefits Reserves Adjustment 563 896 1,128
Total change in accumulated other comprehensive income, Postretirement Benefits Reserves Adjustment (1,364) 1,097 958
Ending Balance, Postretirement Benefits Reserves Adjustment (7,047) (5,683) (6,780)
Other Comprehensive Income Loss Net Of Tax Period Change [Abstract]      
Beginning Balance, Total (19,564) (16,262) (22,239)
Current period change excluding amounts reclassified from accumulated other comprehensive income, Total (492) (4,394) 4,709
Amounts reclassified from accumulated other comprehensive income, Total 563 1,092 1,268
Total change in accumulated other comprehensive income 71 (3,302) 5,977
Ending Balance, Total $ (19,493) $ (19,564) $ (16,262)