Litigation And Other Contingencies (Schedule Of Guarantees) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015
Litigation And Other Contingencies [Line Items]
Guarantees	$ 7,000
Equity Company Obligations [Member]
Litigation And Other Contingencies [Line Items]
Guarantees	3,229	[1]
Other Third Party Obligations [Member]
Litigation And Other Contingencies [Line Items]
Guarantees	3,771
Debt Related Guarantees [Member]
Litigation And Other Contingencies [Line Items]
Guarantees	126
Debt Related Guarantees [Member] | Equity Company Obligations [Member]
Litigation And Other Contingencies [Line Items]
Guarantees	88	[1]
Debt Related Guarantees [Member] | Other Third Party Obligations [Member]
Litigation And Other Contingencies [Line Items]
Guarantees	38
Other Guarantees [Member]
Litigation And Other Contingencies [Line Items]
Guarantees	6,874
Other Guarantees [Member] | Equity Company Obligations [Member]
Litigation And Other Contingencies [Line Items]
Guarantees	3,141	[1]
Other Guarantees [Member] | Other Third Party Obligations [Member]
Litigation And Other Contingencies [Line Items]
Guarantees	$ 3,733

[1] ExxonMobil share