Accounts Receivable, Net

12 Months Ended

Dec. 31, 2012

Receivables [Abstract]

Loans, Notes, Trade and Other Receivables Disclosure [Text Block]

Accounts Receivable, Net

Accounts receivable, net consists of freight and other receivables, reduced by an allowance for bill adjustments and uncollectible accounts, based upon expected collectibility. At December 31, 2012 and 2011, $48 million and $39 million, respectively, of such allowances had been recorded.

At December 31, 2012 and 2011, $36 million and $31 million, respectively, of accounts receivable were greater than 90 days old.