Litigation And Other Contingencies (Schedule Of Guarantees) (Details) $ in Millions	Mar. 31, 2020 USD ($)
Litigation And Other Contingencies [Line Items]
Guarantees	$ 6,458
Equity Company Obligations [Member]
Litigation And Other Contingencies [Line Items]
Guarantees	1,714	[1]
Other Third Party Obligations [Member]
Litigation And Other Contingencies [Line Items]
Guarantees	4,744
Debt Related Guarantees [Member]
Litigation And Other Contingencies [Line Items]
Guarantees	976
Debt Related Guarantees [Member] | Equity Company Obligations [Member]
Litigation And Other Contingencies [Line Items]
Guarantees	868	[1]
Debt Related Guarantees [Member] | Other Third Party Obligations [Member]
Litigation And Other Contingencies [Line Items]
Guarantees	108
Other Guarantees [Member]
Litigation And Other Contingencies [Line Items]
Guarantees	5,482
Other Guarantees [Member] | Equity Company Obligations [Member]
Litigation And Other Contingencies [Line Items]
Guarantees	846	[1]
Other Guarantees [Member] | Other Third Party Obligations [Member]
Litigation And Other Contingencies [Line Items]
Guarantees	$ 4,636

[1] ExxonMobil share