Capital Expenditures [Abstract]

No definition available.

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- Definition

Number of depreciable asset categories to account for depreciation expense for the railroad assets that are depreciated under the group life method.

+ References

No definition available.

+ Details

Name:	csx_NumberOfDepreciableAssetCategoriesForRailroadAssets
Namespace Prefix:	csx_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of total gross assets depreciated under the group-life method of accounting. Does not include other assets which are depreciated on a straight line basis.

+ References

No definition available.

+ Details

Name:	csx_PercentageOfAssetsDepreciatedUnderGroupLifeMethod
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Balance Type:	na
Period Type:	instant

- Definition

Percentage of labor costs relating to the deconstruction of old track based upon an analysis of track replacement process.

+ References

No definition available.

+ Details

Name:	csx_PercentageOfLaborCostRailInstallationDeconstructionOfOldTrack
Namespace Prefix:	csx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of labor costs relating to the installation of new track based upon an analysis of track replacement process.

+ References

No definition available.

+ Details

Name:	csx_PercentageOfLaborCostRailInstallationInstallationOfNewTrack
Namespace Prefix:	csx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The frequency with which life studies are required, by Surface Transportation Board (STB) to be performed.

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

-- None. No documentation exists for this element. --

+ References

No definition available.

+ Details

Name:	csx_RailroadAssetsAbstract
Namespace Prefix:	csx_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585

+ Details

Name:	us-gaap_Depreciation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of gain (loss) on sale or disposal of property, plant and equipment assets, excluding oil and gas property and timber property.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=51717284&loc=d3e1361-107760

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=51719941&loc=d3e2941-110230

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.13)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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Properties (Railroad Assets, Non-Railroad Assets, and Capital Expenditure) (Details)	12 Months Ended
	Dec. 25, 2015 USD ($) categories	Dec. 26, 2014 USD ($)	Dec. 27, 2013 USD ($)
Railroad Assets [Abstract]
Percentage of assets depreciated under the group-life method	86.00%
Total fixed assets	$ 41,574,000,000	$ 39,343,000,000
Annual depreciation expense	$ 1,208,000,000	1,151,000,000	$ 1,104,000,000
Capital Expenditures [Abstract]
Percentage of labor costs relating to the deconstruction of old track (In hundredths)	20.00%
Percentage of labor costs relating to the installation of new track (In hundredths)	80.00%
Minimum [Member]
Railroad Assets [Abstract]
Number of depreciable asset categories for railroad assets \| categories	130
Road - Ties [Member]
Railroad Assets [Abstract]
Total fixed assets	$ 5,077,000,000	4,807,000,000
Number of depreciable asset categories for railroad assets \| categories	18
Total Equipment [Member]
Railroad Assets [Abstract]
Total fixed assets	$ 11,108,000,000	$ 10,108,000,000
Life studies, frequency period	3 years
Total Equipment [Member] \| Minimum [Member]
Railroad Assets [Abstract]
Estimated useful life	3 years	3 years
Total Equipment [Member] \| Maximum [Member]
Railroad Assets [Abstract]
Estimated useful life	38 years	38 years
Road - Total [Member]
Railroad Assets [Abstract]
Total fixed assets	$ 27,564,000,000	$ 26,125,000,000
Life studies, frequency period	6 years
Road - Total [Member] \| Minimum [Member]
Railroad Assets [Abstract]
Estimated useful life	8 years	8 years
Road - Total [Member] \| Maximum [Member]
Railroad Assets [Abstract]
Estimated useful life	90 years	90 years
Technology Equipment [Member] \| Minimum [Member]
Railroad Assets [Abstract]
Estimated useful life	3 years
Abnormal gain (loss) on operating property [Member]
Railroad Assets [Abstract]
Abnormal gains and losses	$ 23,000,000	$ 0	$ 65,000,000
Gain (loss) on non-operating property [Member]
Railroad Assets [Abstract]
Abnormal gains and losses	$ 59,000,000