Accounts Receivable, Net	6 Months Ended
Accounts Receivable, Net	Jun. 30, 2013
Receivables [Abstract]
Accounts Receivable, Net	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 June 30, 2013 and December 31, 2012, $52 million and $48 million, respectively, of such allowances had been recorded. At June 30, 2013 and December 31, 2012, $30 million and $36 million, respectively, of accounts receivable were greater than 90 days old.

The entire disclosure for claims held for amounts due a entity, excluding financing receivables. Examples include, but are not limited to, trade accounts receivables, notes receivables, loans receivables. Includes disclosure for allowance for credit losses.

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