Summary of Significant Accounting Policies (Details)	12 Months Ended
Dec. 31, 2011 years
Notes To Financial Statements [Abstract]
Properties depreciation method by asset class	The cost of properties, including those under capital leases, net of asset impairment write-downs, is depreciated on a straight-line basis over their estimated service lives, measured in years, except for rail which is measured in millions of gross tons per mile. The Company follows the group method of depreciation whereby a single composite depreciation rate is applied to the gross investment in a class of similar assets, despite small differences in the service life or salvage value of individual property units within the same asset class.
Intangible assets amortization method	straight-line basis
Intangible assets
Intangible assets, useful life, minimum (in years)	40
Intangible assets, useful life, maximum (in years)	50
Pensions
Pension Plan amortization of cumulative net actuarial gains and losses	10.00%
Postretirement benefits amortization of cumulative net actuarial gains and losses	10.00%

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Pension Plan's amortization of cumulative net actuarial gains and losses percentage in excess of, the greater of the beginning of year balances of the projected benefit obligation or market-related value of plan assets, over the expected average remaining service life of the employee group covered by the plans.

+ References

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Other postretirement benefits amortization of cumulative net actuarial gains and losses percentage in excess of the projected benefit obligation at the beginning of the year, over the expected average remaining service life of the employee group covered by the plan.

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The amortization method of a major finite-lived intangible asset class. A major class is composed of intangible assets that can be grouped together because they are similar either by their nature or by their use in the operations of a company. The straight-line method is the preferred amortization method, unless another method better reflects the pattern in which the asset is consumed.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 12, 13, 14

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-Name Accounting Standards Codification

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-Section 35

-Paragraph 6

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The maximum useful life of a major finite-lived intangible asset class. A major class is composed of intangible assets that can be grouped together because they are similar either by their nature or by their use in the operations of a company.

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The minimum useful life of a major finite-lived intangible asset class. A major class is composed of intangible assets that can be grouped together because they are similar either by their nature or by their use in the operations of a company.

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- Definition

Describes an entity's methodology for allocating the cost of a property, plant or equipment, less salvage value (if any), over the estimated useful life of the asset in a systematic and rational manner.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 12

-Paragraph 5

-Subparagraph d

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 43

-Chapter 9

-Section C

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