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Accounts receivable
12 Months Ended
Dec. 31, 2012
Notes To Financial Statements [Abstract]  
Accounts receivable

3Accounts receivable

In millions December 31, 2012 2011
Freight   $674 $630
Non-freight     167  206
Gross accounts receivable    841  836
Allowance for doubtful accounts    (10)  (16)
Net accounts receivable   $831 $820