Disclosures About Segments And Related Information (Schedule Of Long-Lived Assets By Geographic Regions) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Long-lived assets	$ 247,101	$ 252,630	$ 244,224
U.S. [Member]
Property, Plant and Equipment [Line Items]
Long-lived assets	108,147	105,101	101,194
Non-U.S. [Member]
Property, Plant and Equipment [Line Items]
Long-lived assets	138,954	147,529	143,030
Canada [Member]
Property, Plant and Equipment [Line Items]
Long-lived assets	37,433	41,138	40,144
Australia [Member]
Property, Plant and Equipment [Line Items]
Long-lived assets	14,548	16,908	16,510
Singapore [Member]
Property, Plant and Equipment [Line Items]
Long-lived assets	11,148	11,292	9,769
Kazakhstan [Member]
Property, Plant and Equipment [Line Items]
Long-lived assets	9,726	10,121	10,325
Nigeria [Member]
Property, Plant and Equipment [Line Items]
Long-lived assets	8,421	9,734	11,314
Papua New Guinea [Member]
Property, Plant and Equipment [Line Items]
Long-lived assets	8,269	8,463	5,719
Angola [Member]
Property, Plant and Equipment [Line Items]
Long-lived assets	7,021	7,689	8,413
Russia [Member]
Property, Plant and Equipment [Line Items]
Long-lived assets	$ 5,456	$ 5,702	$ 4,828