Consolidated Balance Sheets (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 1,672	$ 1,794
Accounts receivable, net	1,279	1,168
Materials and supplies	805	800
Current portion of deferred income taxes	237	341
Other current assets	245	77
Total current assets	4,238	4,180
Property and equipment, net of accumulated depreciation of $1,804 and $1,626, respectively	50,928	50,070
Goodwill	14,836	14,836
Intangible assets, net	962	1,114
Other assets	1,904	1,816
Total assets	72,868	72,016
Current liabilities:
Accounts payable and other current liabilities	2,870	3,122
Long-term debt due within one year	921	453
Total current liabilities	3,791	3,575
Deferred income taxes	16,515	16,319
Long-term debt	14,959	14,080
Intangible liabilities, net	1,087	1,214
Pension and retiree health and welfare liability	755	786
Casualty and environmental liabilities	737	750
Other liabilities	1,008	963
Total liabilities	38,852	37,687
Commitments and contingencies (see Notes 6 and 7)
Equity:
Member's Equity	34,256	34,574
Accumulated other comprehensive loss	(240)	(245)
Total equity	34,016	34,329
Total liabilities and equity	$ 72,868	$ 72,016