Consolidated Balance Sheets (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 2,276	$ 1,960
Accounts receivable, net	1,103	1,150
Materials and supplies	836	739
Current portion of deferred income taxes	205	295
Other current assets	178	121
Total current assets	4,598	4,265
Property and equipment, net of accumulated depreciation of $1,235 and $1,056, respectively	48,498	48,047
Goodwill	14,803	14,803
Intangible assets, net	1,343	1,420
Other assets	1,876	1,845
Total assets	71,118	70,380
Current liabilities:
Accounts payable and other current liabilities	3,082	3,143
Long-term debt due within one year	530	526
Total current liabilities	3,612	3,669
Deferred income taxes	15,682	15,637
Long-term debt	13,295	12,139
Intangible liabilities, net	1,426	1,496
Casualty and environmental liabilities	869	905
Pension and retiree health and welfare liability	733	769
Other liabilities	1,059	1,016
Total liabilities	36,676	35,631
Commitments and contingencies (see Notes 2, 6 and 7)
Equity:
Member's equity	34,653	34,952
Accumulated other comprehensive loss	(211)	(203)
Total equity	34,442	34,749
Total liabilities and equity	$ 71,118	$ 70,380