v2.4.0.6
Debt - Additional Information (Detail) (USD $)
 12 Months Ended
Dec. 31, 2011
Aug. 31, 2011
Dec. 31, 2010
Short-term Debt [Line Items]      
Maturities of long-term borrowings net of unamortized premiums and discounts in 2012 $ 1,013,000,000    
Maturities of long-term borrowings net of unamortized premiums and discounts in 2013 1,275,000,000    
Maturities of long-term borrowings net of unamortized premiums and discounts in 2014 1,527,000,000    
Maturities of long-term borrowings net of unamortized premiums and discounts in 2015 1,571,000,000    
Maturities of long-term borrowings net of unamortized premiums and discounts in 2016 2,364,000,000    
Classification of short-term debt as long-term debt 1,058,000,000    
Total amount under revolving credit facilities   8,000,000,000  
Revolving credit facilities may be used as support for letters of credit 750,000,000    
Minimum limit of debt for cross default provision 200,000,000    
Maturity period of commercial paper (in days) 90    
Direct outstanding borrowings under the revolving credit facilities 0   0
Letters of credit issued under revolving credit facilities 1,954,000,000    
Commercial paper outstanding 1,128,000,000   1,182,000,000
Credit facilities remaining after commercial paper outstanding and issuance of letters of credit 6,800,000,000    
Revolving Credit Facility [Member]
      
Short-term Debt [Line Items]      
Letters of credit issued under revolving credit facilities 40,000,000    
ConocoPhillips [Member]
      
Short-term Debt [Line Items]      
ConocoPhillips Commercial Paper Program 6,350,000,000    
ConocoPhillips Qatar Funding Ltd [Member]
      
Short-term Debt [Line Items]      
ConocoPhillips Commercial Paper Program 1,500,000,000    
9.375% Notes due 2011 [Member]
      
Short-term Debt [Line Items]      
Note repaid at its maturity 328,000,000    
6.50% Notes due 2011 [Member]
      
Short-term Debt [Line Items]      
Note repaid at its maturity 500,000,000    
Old Revolving Credit Facilities [Member]
      
Short-term Debt [Line Items]      
Total amount under revolving credit facilities   7,850,000,000  
Old revolving credit facility expiring in September 2012 [Member]
      
Short-term Debt [Line Items]      
Total amount under revolving credit facilities 7,350,000,000    
Credit facility expiring in August 2016 [Member]
      
Short-term Debt [Line Items]      
Total amount under revolving credit facilities 7,500,000,000    
Revolving credit facility expiring in July 2012 [Member]
      
Short-term Debt [Line Items]      
Total amount under revolving credit facilities $ 500,000,000