v3.19.3.a.u2
Pension And Other Postretirement Benefits (Summary Of The Change In Accumulated Other Comprehensive Income) (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]      
Total (charge)/credit to other comprehensive income, before tax $ (2,041) $ 1,657 $ 1,279
(Charge)/credit to income tax (see Note 4) 550 (470) (290)
(Charge)/credit to investment in equity companies (19) 24 (43)
(Charge)/credit to other comprehensive income including noncontrolling interests, after tax (1,510) 1,211 946
Charge/(credit) to equity of noncontrolling interests 146 (114) 12
Exxon Mobil Corporation Share After Noncontrolling Interest [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total change in accumulated other comprehensive income, Postretirement Benefits Reserves Adjustment (1,364) 1,097 958
U.S. [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total (charge)/credit to other comprehensive income, before tax (135) 156 1,376
Pension Benefits - Non-U.S. [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total (charge)/credit to other comprehensive income, before tax (1,402) 823 63
Other Postretirement Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total (charge)/credit to other comprehensive income, before tax $ (504) $ 678 $ (160)