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Depreciation And Amortization
3 Months Ended
Mar. 31, 2013
Depreciation, Depletion and Amortization [Abstract]  
Property, Plant and Equipment Disclosure [Text Block]
 Depreciation and Amortization
Accumulated depreciation of owned equipment and property at March 31, 2013 and December 31, 2012 was $10.8 billion and $10.6 billion, respectively. Accumulated amortization of equipment and property under capital leases at March 31, 2013 and December 31, 2012 was $219 million and $205 million, respectively.