v2.4.0.6
Supplemental Information On Oil And Gas Operations (Proved Reserves) (Details)
 12 Months Ended
Dec. 31, 2011
MMbls
Dec. 31, 2010
MMbls
Dec. 31, 2009
MMbls
Dec. 31, 2008
MMbls
Reserve Quantities [Line Items]        
Conversion rate of gas reserves from barrels of oil to Boe 6      
U.S. Onshore [Member]
        
Reserve Quantities [Line Items]        
Proved developed and undeveloped reserves 403 411    
Proved developed and undeveloped reserves, revisions other than price (2)      
Proved developed and undeveloped reserves, extensions and discoveries 118      
Canada [Member]
        
Reserve Quantities [Line Items]        
Proved developed and undeveloped reserves 379 420    
Proved developed and undeveloped reserves, revisions other than price (14)      
Proved developed and undeveloped reserves, extensions and discoveries 30      
North America [Member]
        
Reserve Quantities [Line Items]        
Proved developed and undeveloped reserves 782 831    
Proved developed and undeveloped reserves, revisions other than price (16)      
Proved developed and undeveloped reserves, extensions and discoveries 148      
Oil (MMBbls) [Member] | U.S. Onshore [Member]
        
Reserve Quantities [Line Items]        
Proved developed and undeveloped reserves 168 148 139 133
Proved developed and undeveloped reserves, revisions due to prices 2 4 9  
Proved developed and undeveloped reserves, revisions other than price (1) 2    
Proved developed and undeveloped reserves, extensions and discoveries 36 19 9  
Proved developed and undeveloped reserves, production (17) (14) (12)  
Proved developed and undeveloped reserves, sale of reserves   (2)    
Proved developed reserves, volume 146 131 119 111
Proved developed producing reserves, BOE 139 123 112 103
Proved undeveloped reserves, volume 22 17 20 22
Oil (MMBbls) [Member] | U.S. Offshore [Member]
        
Reserve Quantities [Line Items]        
Proved developed and undeveloped reserves     33 34
Proved developed and undeveloped reserves, revisions due to prices   1 2  
Proved developed and undeveloped reserves, revisions other than price   2 1  
Proved developed and undeveloped reserves, extensions and discoveries   1 2  
Proved developed and undeveloped reserves, production   (2) (5)  
Proved developed and undeveloped reserves, sale of reserves   (35) (1)  
Proved developed reserves, volume     21 22
Proved developed producing reserves, BOE     12 9
Proved undeveloped reserves, volume     12 12
Oil (MMBbls) [Member] | Total U.S [Member]
        
Reserve Quantities [Line Items]        
Proved developed and undeveloped reserves 168 148 172 167
Proved developed and undeveloped reserves, revisions due to prices 2 5 11  
Proved developed and undeveloped reserves, revisions other than price (1) 4 1  
Proved developed and undeveloped reserves, extensions and discoveries 36 20 11  
Proved developed and undeveloped reserves, production (17) (16) (17)  
Proved developed and undeveloped reserves, sale of reserves   (37) (1)  
Proved developed reserves, volume 146 131 140 133
Proved developed producing reserves, BOE 139 123 124 112
Proved undeveloped reserves, volume 22 17 32 34
Oil (MMBbls) [Member] | Canada [Member]
        
Reserve Quantities [Line Items]        
Proved developed and undeveloped reserves 537 533 514 134
Proved developed and undeveloped reserves, revisions due to prices (15) (24) 291  
Proved developed and undeveloped reserves, revisions other than price 11 9 (8)  
Proved developed and undeveloped reserves, extensions and discoveries 36 59 122  
Proved developed and undeveloped reserves, production (28) (25) (25)  
Proved developed reserves, volume 163 126 149 110
Proved developed producing reserves, BOE 155 116 137 91
Proved undeveloped reserves, volume 374 407 365 24
Oil (MMBbls) [Member] | North America [Member]
        
Reserve Quantities [Line Items]        
Proved developed and undeveloped reserves 705 681 686 301
Proved developed and undeveloped reserves, revisions due to prices (13) (19) 302  
Proved developed and undeveloped reserves, revisions other than price 10 13 (7)  
Proved developed and undeveloped reserves, extensions and discoveries 72 79 133  
Proved developed and undeveloped reserves, production (45) (41) (42)  
Proved developed and undeveloped reserves, sale of reserves   (37) (1)  
Proved developed reserves, volume 309 257 289 243
Proved developed producing reserves, BOE 294 239 261 203
Proved undeveloped reserves, volume 396 424 397 58
Gas (Bcf) [Member] | U.S. Onshore [Member]
        
Reserve Quantities [Line Items]        
Proved developed and undeveloped reserves 9,507 9,065 8,127 7,979
Proved developed and undeveloped reserves, revisions due to prices (1) 449 (661)  
Proved developed and undeveloped reserves, revisions other than price (243) 105 119  
Proved developed and undeveloped reserves, extensions and discoveries 1,410 1,088 1,387  
Proved developed and undeveloped reserves, purchase of reserves 16 12 1  
Proved developed and undeveloped reserves, production (740) (699) (698)  
Proved developed and undeveloped reserves, sale of reserves   (17)    
Proved developed reserves, volume 7,957 7,280 6,447 6,469
Proved developed producing reserves, BOE 7,409 6,702 5,860 5,787
Proved undeveloped reserves, volume 1,550 1,785 1,680 1,510
Gas (Bcf) [Member] | U.S. Offshore [Member]
        
Reserve Quantities [Line Items]        
Proved developed and undeveloped reserves     342 390
Proved developed and undeveloped reserves, revisions due to prices   2 (4)  
Proved developed and undeveloped reserves, revisions other than price   (26) (62)  
Proved developed and undeveloped reserves, extensions and discoveries   7 64  
Proved developed and undeveloped reserves, production   (17) (45)  
Proved developed and undeveloped reserves, sale of reserves   (308) (1)  
Proved developed reserves, volume     185 212
Proved developed producing reserves, BOE     137 64
Proved undeveloped reserves, volume     157 178
Gas (Bcf) [Member] | Total U.S [Member]
        
Reserve Quantities [Line Items]        
Proved developed and undeveloped reserves 9,507 9,065 8,469 8,369
Proved developed and undeveloped reserves, revisions due to prices (1) 451 (665)  
Proved developed and undeveloped reserves, revisions other than price (243) 79 57  
Proved developed and undeveloped reserves, extensions and discoveries 1,410 1,095 1,451  
Proved developed and undeveloped reserves, purchase of reserves 16 12 1  
Proved developed and undeveloped reserves, production (740) (716) (743)  
Proved developed and undeveloped reserves, sale of reserves   (325) (1)  
Proved developed reserves, volume 7,957 7,280 6,632 6,681
Proved developed producing reserves, BOE 7,409 6,702 5,997 5,851
Proved undeveloped reserves, volume 1,550 1,785 1,837 1,688
Gas (Bcf) [Member] | Canada [Member]
        
Reserve Quantities [Line Items]        
Proved developed and undeveloped reserves 979 1,218 1,288 1,510
Proved developed and undeveloped reserves, revisions due to prices (60) 21 (29)  
Proved developed and undeveloped reserves, revisions other than price (38) (17) (14)  
Proved developed and undeveloped reserves, extensions and discoveries 58 131 67  
Proved developed and undeveloped reserves, purchase of reserves 20 9 6  
Proved developed and undeveloped reserves, production (213) (214) (223)  
Proved developed and undeveloped reserves, sale of reserves (6)   (29)  
Proved developed reserves, volume 951 1,144 1,213 1,357
Proved developed producing reserves, BOE 862 1,031 1,075 1,194
Proved undeveloped reserves, volume 28 74 75 153
Gas (Bcf) [Member] | North America [Member]
        
Reserve Quantities [Line Items]        
Proved developed and undeveloped reserves 10,486 10,283 9,757 9,879
Proved developed and undeveloped reserves, revisions due to prices (61) 472 (694)  
Proved developed and undeveloped reserves, revisions other than price (281) 62 43  
Proved developed and undeveloped reserves, extensions and discoveries 1,468 1,226 1,518  
Proved developed and undeveloped reserves, purchase of reserves 36 21 7  
Proved developed and undeveloped reserves, production (953) (930) (966)  
Proved developed and undeveloped reserves, sale of reserves (6) (325) (30)  
Proved developed reserves, volume 8,908 8,424 7,845 8,038
Proved developed producing reserves, BOE 8,271 7,733 7,072 7,045
Proved undeveloped reserves, volume 1,578 1,859 1,912 1,841
Natural Gas Liquids (MMBbls) [Member] | U.S. Onshore [Member]
        
Reserve Quantities [Line Items]        
Proved developed and undeveloped reserves 525 449 385 315
Proved developed and undeveloped reserves, revisions due to prices 4 14 (11)  
Proved developed and undeveloped reserves, revisions other than price 1 13 36  
Proved developed and undeveloped reserves, extensions and discoveries 102 68 70  
Proved developed and undeveloped reserves, purchase of reserves 2      
Proved developed and undeveloped reserves, production (33) (28) (25)  
Proved developed and undeveloped reserves, sale of reserves   (3)    
Proved developed reserves, volume 402 353 293 260
Proved developed producing reserves, BOE 372 318 265 230
Proved undeveloped reserves, volume 123 96 92 55
Natural Gas Liquids (MMBbls) [Member] | U.S. Offshore [Member]
        
Reserve Quantities [Line Items]        
Proved developed and undeveloped reserves     2 2
Proved developed and undeveloped reserves, revisions other than price   3 1  
Proved developed and undeveloped reserves, production     (1)  
Proved developed and undeveloped reserves, sale of reserves   (5)    
Proved developed reserves, volume     1 1
Proved developed producing reserves, BOE     1  
Proved undeveloped reserves, volume     1 1
Natural Gas Liquids (MMBbls) [Member] | Total U.S [Member]
        
Reserve Quantities [Line Items]        
Proved developed and undeveloped reserves 525 449 387 317
Proved developed and undeveloped reserves, revisions due to prices 4 14 (11)  
Proved developed and undeveloped reserves, revisions other than price 1 16 37  
Proved developed and undeveloped reserves, extensions and discoveries 102 68 70  
Proved developed and undeveloped reserves, purchase of reserves 2      
Proved developed and undeveloped reserves, production (33) (28) (26)  
Proved developed and undeveloped reserves, sale of reserves   (8)    
Proved developed reserves, volume 402 353 294 261
Proved developed producing reserves, BOE 372 318 266 230
Proved undeveloped reserves, volume 123 96 93 56
Natural Gas Liquids (MMBbls) [Member] | Canada [Member]
        
Reserve Quantities [Line Items]        
Proved developed and undeveloped reserves 27 30 34 35
Proved developed and undeveloped reserves, revisions due to prices (1) (1) 2  
Proved developed and undeveloped reserves, revisions other than price   (1)    
Proved developed and undeveloped reserves, extensions and discoveries 2 2 1  
Proved developed and undeveloped reserves, production (4) (4) (4)  
Proved developed reserves, volume 26 28 32 31
Proved developed producing reserves, BOE 24 26 28 29
Proved undeveloped reserves, volume 1 2 2 4
Natural Gas Liquids (MMBbls) [Member] | North America [Member]
        
Reserve Quantities [Line Items]        
Proved developed and undeveloped reserves 552 479 421 352
Proved developed and undeveloped reserves, revisions due to prices 3 13 (9)  
Proved developed and undeveloped reserves, revisions other than price 1 15 37  
Proved developed and undeveloped reserves, extensions and discoveries 104 70 71  
Proved developed and undeveloped reserves, purchase of reserves 2      
Proved developed and undeveloped reserves, production (37) (32) (30)  
Proved developed and undeveloped reserves, sale of reserves   (8)    
Proved developed reserves, volume 428 381 326 292
Proved developed producing reserves, BOE 396 344 294 259
Proved undeveloped reserves, volume 124 98 95 60
Total (MMBoe) [Member] | U.S. Onshore [Member]
        
Reserve Quantities [Line Items]        
Proved developed and undeveloped reserves 2,278 [1] 2,107 [1] 1,878 [1] 1,777 [1]
Proved developed and undeveloped reserves, revisions due to prices 6 [1] 92 [1] (113) [1]  
Proved developed and undeveloped reserves, revisions other than price (41) [1] 32 [1] 57 [1]  
Proved developed and undeveloped reserves, extensions and discoveries 374 [1] 269 [1] 311 [1]  
Proved developed and undeveloped reserves, purchase of reserves 5 [1] 2 [1]    
Proved developed and undeveloped reserves, production (173) [1] (158) [1] (154) [1]  
Proved developed and undeveloped reserves, sale of reserves   (8) [1]    
Proved developed producing reserves, BOE 1,746 [1] 1,557 [1] 1,354 [1] 1,298 [1]
Proved developed reserves, BOE 1,875 [1] 1,696 [1] 1,486 [1] 1,449 [1]
Proved undeveloped reserves, BOE 403 [1] 411 [1] 392 [1] 328 [1]
Total (MMBoe) [Member] | U.S. Offshore [Member]
        
Reserve Quantities [Line Items]        
Proved developed and undeveloped reserves     92 [1] 101 [1]
Proved developed and undeveloped reserves, revisions due to prices   1 [1] 1 [1]  
Proved developed and undeveloped reserves, revisions other than price   1 [1] (8) [1]  
Proved developed and undeveloped reserves, extensions and discoveries   2 [1] 12 [1]  
Proved developed and undeveloped reserves, production   (5) [1] (13) [1]  
Proved developed and undeveloped reserves, sale of reserves   (91) [1] (1) [1]  
Proved developed producing reserves, BOE     35 [1] 20 [1]
Proved developed reserves, BOE     53 [1] 59 [1]
Proved undeveloped reserves, BOE     39 [1] 42 [1]
Total (MMBoe) [Member] | Total U.S [Member]
        
Reserve Quantities [Line Items]        
Proved developed and undeveloped reserves 2,278 [1] 2,107 [1] 1,970 [1] 1,878 [1]
Proved developed and undeveloped reserves, revisions due to prices 6 [1] 93 [1] (112) [1]  
Proved developed and undeveloped reserves, revisions other than price (41) [1] 33 [1] 49 [1]  
Proved developed and undeveloped reserves, extensions and discoveries 374 [1] 271 [1] 323 [1]  
Proved developed and undeveloped reserves, purchase of reserves 5 [1] 2 [1]    
Proved developed and undeveloped reserves, production (173) [1] (163) [1] (167) [1]  
Proved developed and undeveloped reserves, sale of reserves   (99) [1] (1) [1]  
Proved developed producing reserves, BOE 1,746 [1] 1,557 [1] 1,389 [1] 1,318 [1]
Proved developed reserves, BOE 1,875 [1] 1,696 [1] 1,539 [1] 1,508 [1]
Proved undeveloped reserves, BOE 403 [1] 411 [1] 431 [1] 370 [1]
Total (MMBoe) [Member] | Canada [Member]
        
Reserve Quantities [Line Items]        
Proved developed and undeveloped reserves 727 [1] 766 [1] 763 [1] 421 [1]
Proved developed and undeveloped reserves, revisions due to prices (27) [1] (21) [1] 289 [1]  
Proved developed and undeveloped reserves, revisions other than price 6 [1] 5 [1] (11) [1]  
Proved developed and undeveloped reserves, extensions and discoveries 47 [1] 83 [1] 135 [1]  
Proved developed and undeveloped reserves, purchase of reserves 3 [1] 2 [1] 1 [1]  
Proved developed and undeveloped reserves, production (67) [1] (65) [1] (66) [1]  
Proved developed and undeveloped reserves, sale of reserves (1) [1] (1) [1] (6) [1]  
Proved developed producing reserves, BOE 323 [1] 314 [1] 344 [1] 319 [1]
Proved developed reserves, BOE 348 [1] 346 [1] 383 [1] 367 [1]
Proved undeveloped reserves, BOE 379 [1] 420 [1] 380 [1] 54 [1]
Total (MMBoe) [Member] | North America [Member]
        
Reserve Quantities [Line Items]        
Proved developed and undeveloped reserves 3,005 [1] 2,873 [1] 2,733 [1] 2,299 [1]
Proved developed and undeveloped reserves, revisions due to prices (21) [1] 72 [1] 177 [1]  
Proved developed and undeveloped reserves, revisions other than price (35) [1] 38 [1] 38 [1]  
Proved developed and undeveloped reserves, extensions and discoveries 421 [1] 354 [1] 458 [1]  
Proved developed and undeveloped reserves, purchase of reserves 8 [1] 4 [1] 1 [1]  
Proved developed and undeveloped reserves, production (240) [1] (228) [1] (233) [1]  
Proved developed and undeveloped reserves, sale of reserves (1) [1] (100) [1] (7) [1]  
Proved developed producing reserves, BOE 2,069 [1] 1,871 [1] 1,733 [1] 1,637 [1]
Proved developed reserves, BOE 2,223 [1] 2,042 [1] 1,922 [1] 1,875 [1]
Proved undeveloped reserves, BOE 782 [1] 831 [1] 811 [1] 424 [1]
[1] Gas reserves are converted to Boe at the rate of six Mcf per Bbl of oil, based upon the approximate relative energy content of gas and oil. This rate is not necessarily indicative of the relationship of natural gas and oil prices. Natural gas liquids reserves are converted to Boe on a one-to-one basis with oil.