XML 42 R32.htm IDEA: XBRL DOCUMENT v3.8.0.1
Accounts Receivable (Tables)
12 Months Ended
Dec. 31, 2017
Accounts receivable  
Accounts receivable
In millionsDecember 31,20172016
Freight$828$752
Non-freight 172151
Gross accounts receivable1,000903
Allowance for doubtful accounts(16)(28)
Net accounts receivable$984$875