Number of locomotives under the long-term maintenance program.

No definition available.

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- Definition

Percentage of locomotive fleet currently covered under a long-term maintenance program.

+ References

No definition available.

+ Details

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- Definition

Maintenance costs incurred and directly related to services rendered by an entity during the reporting period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.2(d))

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

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- Definition

Sets forth the number of units of goods that must be purchased within the specified time period of the agreement to avoid penalties or unfavorable effects on pricing, among other adverse consequences.

+ References

No definition available.

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- Definition

The remaining amount of the fixed and determinable portion of an unrecorded unconditional purchase obligation to be paid in more than four and within five years from the balance sheet date.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 47

-Paragraph 7

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 FASB

-Name Accounting Standards Codification

-Topic 440

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25336-109308

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- Definition

The remaining amount of the fixed and determinable portion of an unrecorded unconditional purchase obligation to be paid within one year of the balance sheet date.

+ References

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- Definition

The remaining amount of the fixed and determinable portion of an unrecorded unconditional purchase obligation to be paid in more than three and within four years from the balance sheet date.

+ References

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- Definition

The remaining amount of the fixed and determinable portion of an unrecorded unconditional purchase obligation to be paid in more than one and within two years from the balance sheet date.

+ References

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- Definition

The remaining amount of the fixed and determinable portion of an unrecorded unconditional purchase obligation to be paid in more than two and within three years from the balance sheet date.

+ References

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- Definition

The amount of the fixed and determinable portion of an unrecorded unconditional purchase obligation as of the balance sheet date.

+ References

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- Definition

The remaining amount of the fixed and determinable portion of an unrecorded unconditional purchase obligation to be paid after five years from the balance sheet date.

+ References

No definition available.

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Commitments and Contingencies (Purchase Commitments) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 30, 2011	Dec. 31, 2010	Dec. 25, 2009
Unrecorded Unconditional Purchase Obligation [Line Items]
Percentage of Locomotive Fleet Under Long-Term Maintenance Program	46.00%
Amounts Paid	$ 281	$ 252	$ 237
Number of locomotives under the long term maintenance plan	1,943	1,869	1,891
Unrecorded Unconditional Purchase Obligation [Abstract]
2012	828
2013	357
2014	336
2015	322
2016	297
Thereafter	2,488
Total	4,628
Locomotive Purchase Obligations [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Remaining purchase obligation	65
Unrecorded Unconditional Purchase Obligation [Abstract]
2012	475
2013	301
2014	300
2015	288
2016	285
Thereafter	2,429
Total	4,078
Other Purchase Obligations [Member]
Unrecorded Unconditional Purchase Obligation [Abstract]
2012	353
2013	56
2014	36
2015	34
2016	12
Thereafter	59
Total	$ 550