v2.4.0.6
Asset Retirement Obligations (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Asset Retirement Obligation Disclosure [Line Items]      
Asset retirement obligations as of beginning of year $ 1,497 $ 1,513  
Liabilities incurred 53 55  
Liabilities settled (82) (129)  
Revision of estimated obligation 25 194  
Accretion expense on discounted obligation 92 92 91
Foreign currency translation adjustment (22) 41  
Asset retirement obligations as of end of year 1,563 1,497 1,513
Less current portion 67 74  
Asset retirement obligations, long-term 1,496 1,423  
Assumed By Others [Member]
     
Asset Retirement Obligation Disclosure [Line Items]      
Liabilities settled   $ (269)