Litigation And Other Contingencies (Schedule Of Guarantees) (Details) $ in Millions	Dec. 31, 2018 USD ($)
Loss Contingencies [Line Items]
Guarantees	$ 5,838
Equity Company Obligations [Member]
Loss Contingencies [Line Items]
Guarantees	1,387	[1]
Other Third-Party Obligations [Member]
Loss Contingencies [Line Items]
Guarantees	4,451
Debt-Related Guarantees [Member]
Loss Contingencies [Line Items]
Guarantees	608
Debt-Related Guarantees [Member] | Equity Company Obligations [Member]
Loss Contingencies [Line Items]
Guarantees	537	[1]
Debt-Related Guarantees [Member] | Other Third-Party Obligations [Member]
Loss Contingencies [Line Items]
Guarantees	71
Other Guarantees [Member]
Loss Contingencies [Line Items]
Guarantees	5,230
Other Guarantees [Member] | Equity Company Obligations [Member]
Loss Contingencies [Line Items]
Guarantees	850	[1]
Other Guarantees [Member] | Other Third-Party Obligations [Member]
Loss Contingencies [Line Items]
Guarantees	$ 4,380

[1] ExxonMobil share.