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Commitments and Contingencies (Environmental) (Details) (USD $)
In Millions, unless otherwise specified
9 Months Ended
Sep. 30, 2012
Dec. 31, 2011
Site Contingency [Line Items]    
Number Of Years Passed Since Alleged Release 25 years  
Accrual for Environmental Loss Contingencies Disclosure [Abstract]    
Accrual for Environmental Loss Contingencies $ 72 $ 81
Duncan, Oklahoma environmental matter
   
Site Contingency [Line Items]    
Accrual for site contingency 26  
Superfund sites
   
Site Contingency [Line Items]    
Accrual for site contingency $ 6  
Number of superfund sites 9