v2.4.0.6
Supplemental Information On Oil And Gas Operations (Proved Undeveloped Reserves) (Details)
12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
U.S. Onshore [Member]
   
Reserve Quantities [Line Items]    
Proved undeveloped reserves 403 411
Proved Undeveloped Reserves, Extensions and discoveries 118  
Proved Undeveloped Reserves, Revisions due to prices (2)  
Proved Undeveloped Reserves, Revisions other than price (56)  
Proved Undeveloped Reserves, Conversion to proved developed reserves (68)  
Canada [Member]
   
Reserve Quantities [Line Items]    
Proved undeveloped reserves 379 420
Proved Undeveloped Reserves, Extensions and discoveries 30  
Proved Undeveloped Reserves, Revisions due to prices (14)  
Proved Undeveloped Reserves, Revisions other than price 5  
Proved Undeveloped Reserves, Conversion to proved developed reserves (62)  
North America [Member]
   
Reserve Quantities [Line Items]    
Proved undeveloped reserves 782 831
Proved Undeveloped Reserves, Extensions and discoveries 148  
Proved Undeveloped Reserves, Revisions due to prices (16)  
Proved Undeveloped Reserves, Revisions other than price (51)  
Proved Undeveloped Reserves, Conversion to proved developed reserves (130)