Leases (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Future Minimum Lease Payments For Capital Leases [Abstract]
Minimum capital lease payments - 2014	$ 272
Minimum capital lease payments - 2015	260
Minimum capital lease payments - 2016	239
Minimum capital lease payments - 2017	247
Minimum capital lease payments - 2018	225
Minimum capital lease payments - later years	957
Total minimum capital lease payments	2,200
Capital lease payments - amount representing interest	(498)
Capital lease payments - present value of minimum lease payments	1,702
Properties held under capital leases	2,486	2,467
Properties held under capital leases - accumulated depreciation	1,092	966
Lease payments related to locomotives	94.00%
Future Minimum Lease Payments For Operating Leases [Abstract]
Minimum operating lease payments - 2014	512
Minimum operating lease payments - 2015	477
Minimum operating lease payments - 2016	438
Minimum operating lease payments - 2017	400
Minimum operating lease payments - 2018	332
Minimum operating lease payments - later years	1,907
Total minimum operating lease payments	4,066
Rent expense for operating leases with terms exceeding one month	$ 618	$ 631	$ 637

Percent of capital lease payments related to locomotives.

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Amount before accumulated depreciation of leased physical assets used in the normal conduct of business to produce goods and services.

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Amount of minimum lease payments for capital leases.

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Amount of minimum lease payments maturing in the next fiscal year following the latest fiscal year for capital leases.

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Amount of minimum lease payments maturing in the fifth fiscal year following the latest fiscal year for capital leases.

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Amount of minimum lease payments maturing in the forth fiscal year following the latest fiscal year for capital leases.

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Amount of minimum lease payments maturing in the third fiscal year following the latest fiscal year for capital leases.

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Amount of minimum lease payments maturing in the second fiscal year following the latest fiscal year for capital leases.

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Amount of minimum lease payments maturing after the fifth fiscal year following the latest fiscal year for capital leases.

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Amount necessary to reduce net minimum lease payments to present value for capital leases.

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Present value of minimum lease payments for capital leases net of executory costs, including amounts paid by the lessee to the lessor for insurance, maintenance and taxes.

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The total charge for the use of long-lived depreciable assets subject to a lease meeting the criteria for capitalization.

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Amount of required minimum rental payments for leases having an initial or remaining non-cancelable letter-terms in excess of one year.

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Amount of required minimum rental payments maturing in the second fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

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