v3.3.1.900
Pension And Other Postretirement Benefits (Summary Of The Change In Accumulated Other Comprehensive Income) (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]      
Total (charge)/credit to other comprehensive income, before tax $ 5,535 $ (4,619) $ 7,281
(Charge)/credit to income tax (see Note 4) (1,810) 1,549 (2,336)
(Charge)/credit to investment in equity companies 81 (81) 49
(Charge)/credit to other comprehensive income including noncontrolling interests, after tax 3,806 (3,151) 4,994
Charge/(credit) to equity of noncontrolling interests (202) 85 (279)
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 3,604 (3,066) 4,715
Pension Benefits - U.S. [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total (charge)/credit to other comprehensive income, before tax 457 (1,776) 2,678
Pension Benefits - Non-U.S. [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total (charge)/credit to other comprehensive income, before tax 3,741 (1,463) 3,054
Other Postretirement Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total (charge)/credit to other comprehensive income, before tax $ 1,337 $ (1,380) $ 1,549