Accounts receivable (Tables)

12 Months Ended

Dec. 31, 2012

Notes To Financial Statements [Abstract]

Accounts 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