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Major Customers and Concentration of Credit Risk
 12 Months Ended
Dec. 31, 2011
Major Customers and Concentration of Credit Risk  
Major Customers and Concentration of Credit Risk

Note 8—Major Customers and Concentration of Credit Risk

 

Marathon Petroleum Corporation and its affiliates accounted for 16%, 14% and 14% of our revenues for each of the three years ended December 31, 2011, 2010 and 2009, respectively. ConocoPhillips Company accounted for 10%, 10% and 12% of our revenues for the years ended December 31, 2011, 2010 and 2009, respectively. No other customers accounted for 10% or more of our revenues during any of the three years ended December 31, 2011. The majority of revenues from these customers pertain to our supply and logistics operations. We believe that the loss of these customers would have only a short-term impact on our operating results. There is risk, however, that we would not be able to identify and access a replacement market at comparable margins.

 

Financial instruments that potentially subject us to concentrations of credit risk consist principally of trade receivables. Our accounts receivable are primarily from purchasers and shippers of crude oil. This industry concentration has the potential to impact our overall exposure to credit risk in that the customers may be similarly affected by changes in economic, industry or other conditions. We review credit exposure and financial information of our counterparties and generally require letters of credit for receivables from customers that are not considered creditworthy, unless the credit risk can otherwise be reduced. See Note 2 for additional discussion of our accounts receivable and our review of credit exposure.