v2.4.0.6
Accounting For Suspended Exploratory Well Costs (Schedule Of Period End Capitalized Suspended Exploratory Well Costs) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Dec. 31, 2008
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]        
Capitalized for a period of one year or less $ 310 $ 1,103 $ 624  
Capitalized suspended exploratory well costs, total 2,881 2,893 2,005 1,585
Capitalized For A Period Of Between One And Five Years [Member]
        
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]        
Capitalized suspended exploratory well costs 1,922 1,294 924  
Capitalized For A Period Of Between Five And Ten Years [Member]
        
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]        
Capitalized suspended exploratory well costs 409 278 220  
Capitalized For A Period Of Greater Than Ten Years [Member]
        
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]        
Capitalized suspended exploratory well costs 240 218 237  
Capitalized For A Period Greater Than One Year [Member]
        
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]        
Capitalized suspended exploratory well costs $ 2,571 $ 1,790 $ 1,381