v2.4.0.6
Goodwill and Intangibles - Summary of Changes in Carrying Amount of Goodwill (Detail) (USD $)
In Millions, unless otherwise specified
 12 Months Ended 12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2011
E&P [Member]
Dec. 31, 2010
E&P [Member]
Dec. 31, 2009
E&P [Member]
Dec. 31, 2011
R&M [Member]
Dec. 31, 2010
R&M [Member]
Goodwill [Line Items]              
Goodwill gross, beginning balance $ 29,076 $ 29,081 $ 25,443 [1] $ 25,443 [1] $ 25,443 [1] $ 3,633 [1] $ 3,638 [1]
Accumulated impairment losses, beginning balance (25,443) (25,443) (25,443) [1] (25,443) [1]      
Goodwill, beginning balance 3,633 [2] 3,638       3,633 [1] 3,638 [1]
Goodwill allocated to assets held for sale or sold (273)         (273) [1]  
Tax and other adjustments (28) (5)       (28) [1] (5) [1]
Goodwill gross, ending balance 28,775 29,076 25,443 [1] 25,443 [1] 25,443 [1] 3,332 [1] 3,633 [1]
Accumulated impairment losses, ending balance (25,443) (25,443) (25,443) [1] (25,443) [1]      
Goodwill, ending Balance $ 3,332 [2] $ 3,633 [2]       $ 3,332 [1] $ 3,633 [1]
[1] E&P represents continuing operations, and R&M represents discontinued operations.
[2] Certain amounts have been restated to reflect a prior period adjustment. See Note 21-Accumulated Other Comprehensive Income, in the Notes to Consolidated Financial Statements.