v2.4.0.6
Supplemental Information On Oil And Gas Operations (Capitalized Costs) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2011
Dec. 31, 2010
Capitalized Costs Relating to Oil and Gas Producing Activities, by Geographic Area [Line Items]    
Capitalized Costs, Proved properties $ 61,696 $ 56,012
United States [Member]
    
Capitalized Costs Relating to Oil and Gas Producing Activities, by Geographic Area [Line Items]    
Capitalized Costs, Proved properties 41,397 36,301
Capitalized Costs, Unproved properties 2,347 2,156
Capitalized Costs, Total oil & gas properties 43,744 38,457
Capitalized Costs, Accumulated DD&A (29,742) (28,546)
Net capitalized costs 14,002 9,911
Canada [Member]
    
Capitalized Costs Relating to Oil and Gas Producing Activities, by Geographic Area [Line Items]    
Capitalized Costs, Proved properties 20,299 19,711
Capitalized Costs, Unproved properties 1,635 1,278
Capitalized Costs, Total oil & gas properties 21,934 20,989
Capitalized Costs, Accumulated DD&A (14,585) (14,130)
Net capitalized costs 7,349 6,859
North America [Member]
    
Capitalized Costs Relating to Oil and Gas Producing Activities, by Geographic Area [Line Items]    
Capitalized Costs, Proved properties 61,696 56,012
Capitalized Costs, Unproved properties 3,982 3,434
Capitalized Costs, Total oil & gas properties 65,678 59,446
Capitalized Costs, Accumulated DD&A (44,327) (42,676)
Net capitalized costs $ 21,351 $ 16,770