Disclosures About Segments And Related Information (Schedule Of Long-Lived Assets By Geographic Regions) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Long-lived assets	$ 253,018	$ 247,101	$ 252,630
U.S. [Member]
Property, Plant and Equipment [Line Items]
Long-lived assets	114,372	108,147	105,101
Non-U.S. [Member]
Property, Plant and Equipment [Line Items]
Long-lived assets	138,646	138,954	147,529
Canada [Member]
Property, Plant and Equipment [Line Items]
Long-lived assets	39,130	37,433	41,138
Australia [Member]
Property, Plant and Equipment [Line Items]
Long-lived assets	13,933	14,548	16,908
Singapore [Member]
Property, Plant and Equipment [Line Items]
Long-lived assets	11,645	11,148	11,292
Kazakhstan [Member]
Property, Plant and Equipment [Line Items]
Long-lived assets	9,315	9,726	10,121
Papua New Guinea [Member]
Property, Plant and Equipment [Line Items]
Long-lived assets	8,057	8,269	8,463
Nigeria [Member]
Property, Plant and Equipment [Line Items]
Long-lived assets	7,640	8,421	9,734
Angola [Member]
Property, Plant and Equipment [Line Items]
Long-lived assets	5,784	7,021	7,689
United Arab Emirates [Member]
Property, Plant and Equipment [Line Items]
Long-lived assets	5,262	4,859	4,304
Russia [Member]
Property, Plant and Equipment [Line Items]
Long-lived assets	$ 5,135	$ 5,456	$ 5,702