Exploratory Costs (Schedule Of Capitalized Exploratory Well And Project Activity) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Dec. 31, 2013
Beginning capitalized exploratory costs	$ 159
Additions to exploratory costs pending the determination of proved reserves	307
Reclassification due to determination of proved reserves	(210)
Exploratory well costs charged to exploration expense	(1)
Ending capitalized exploratory costs	248	[1]
Disposal Group, Including Discontinued Operation, Property, Plant, and Equipment, Net	478		526
Capitalized exploratory costs that have been suspended, One year or less	211		116
Capitalized Exploratory Well Costs that Have Been Capitalized for Period Greater than One Year	37		43
Number of projects with exploratory costs that have been suspended for a period greater than one year	1		1
Capitalized exploratory costs [Member]
Impairment of oil and gas properties	(7)
Disposal Group, Including Discontinued Operation, Property, Plant, and Equipment, Net	$ 60

[1] (a)Includes $60 million of capitalized exploratory well costs classified as held for sale in the accompanying consolidated balance sheet as of March 31, 2014.