XML 103 R89.htm IDEA: XBRL DOCUMENT
v3.3.1.900

Fair Value Measurements (Pension Plan Assets) (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 25, 2015 | Dec. 26, 2014
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | $ 2,309 | $ 2,504
Defined Benefit Plan, Fair Value of Plan Assets Excluding Assets Measured at NAV | 1,393 | 1,528
Alternative Investments, Fair Value Disclosure | $ 916 | 976
Equity [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Investment committee equity target allocation percentage of pension assets | 70.00% |
Pension plan assets at fair value | $ 1,626 | 1,715
Common Stock [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | $ 738 | 787
Fixed Income [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Investment committee equity target allocation percentage of pension assets | 30.00% |
Pension plan assets at fair value | $ 641 | 740
Mutual funds [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 15 | 20
Cash equivalents [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 8 | 1
Corporate bonds [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 480 | 539
Government securities [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 132 | 164
Asset-backed securities [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 14 | 15
Derivatives and other [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 6 | 2
Level 1 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 761 | 808
Defined Benefit Plan, Fair Value of Plan Assets Excluding Assets Measured at NAV | 761 | 808
Level 1 [Member] | Common Stock [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 738 | 787
Level 1 [Member] | Mutual funds [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 15 | 20
Level 1 [Member] | Cash equivalents [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 8 | 1
Level 1 [Member] | Corporate bonds [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 0 | 0
Level 1 [Member] | Government securities [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 0 | 0
Level 1 [Member] | Asset-backed securities [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 0 | 0
Level 1 [Member] | Derivatives and other [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 0 | 0
Level 2 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 632 | 720
Defined Benefit Plan, Fair Value of Plan Assets Excluding Assets Measured at NAV | 632 | 720
Level 2 [Member] | Common Stock [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 0 | 0
Level 2 [Member] | Mutual funds [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 0 | 0
Level 2 [Member] | Cash equivalents [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 0 | 0
Level 2 [Member] | Corporate bonds [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 480 | 539
Level 2 [Member] | Government securities [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 132 | 164
Level 2 [Member] | Asset-backed securities [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 14 | 15
Level 2 [Member] | Derivatives and other [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 6 | 2
Level 3 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 0 | 0
Defined Benefit Plan, Fair Value of Plan Assets Excluding Assets Measured at NAV | 0 | 0
Level 3 [Member] | Common Stock [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 0 | 0
Level 3 [Member] | Mutual funds [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 0 | 0
Level 3 [Member] | Cash equivalents [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 0 | 0
Level 3 [Member] | Corporate bonds [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 0 | 0
Level 3 [Member] | Government securities [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 0 | 0
Level 3 [Member] | Asset-backed securities [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | 0 | 0
Level 3 [Member] | Derivatives and other [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension plan assets at fair value | $ 0 | $ 0

X
- Definition Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets. These assets exclude those measured at net asset value. + References No definition available. + Details
Name: | csx_DefinedBenefitPlanFairValueofPlanAssetsExcludingAssetsMeasuredatNAV
Namespace Prefix: | csx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value of investments in certain entities that calculate net asset value per share, including, but not limited to, by unit, membership interest, or other ownership interest. Investments include, but are not limited to, investments in certain hedge funds, venture capital funds, private equity funds, real estate partnerships or funds. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 6A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=36462937&loc=SL6742756-110258 + Details
Name: | us-gaap_AlternativeInvestmentsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 30 -Section 35 -Paragraph 50 -URI http://asc.fasb.org/extlink&oid=49178875&loc=d3e12355-114930 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Target allocation of investments of this type to total plan assets presented on a weighted average basis. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (c)(i) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e2446-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(i) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanTargetPlanAssetAllocations
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_EquityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_CommonStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_FixedIncomeFundsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=csx_MutualFundsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_CashEquivalentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_USTreasuryAndGovernmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=csx_DerivativesAndOtherMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |