Derivative Asset, Notional Amount Settled

No definition available.

Name:	csx_DerivativeAssetNotionalAmountSettled
Namespace Prefix:	csx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Derivative, Number Of Fair Value Hedges

+ References

No definition available.

+ Details

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Namespace Prefix:	csx_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value of all asset derivatives designated as cash flow hedging instruments.

+ References

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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

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+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Nominal or face amount used to calculate payments on the derivative asset.

+ References

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+ Details

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

- Definition

Period the derivative contract is outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeTermOfContract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value as of the balance sheet date of all derivative assets designated as interest rate fair value hedging instruments.

+ References

+ Details

Name:	us-gaap_InterestRateFairValueHedgeAssetAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value as of the balance sheet date of all derivative liabilities designated as interest rate fair value hedging instruments.

+ References

+ Details

Name:	us-gaap_InterestRateFairValueHedgeLiabilityAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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-Subparagraph (SX 210.4-08(f))
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+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Other cash or noncash adjustments to reconcile net income to cash provided by (used in) operating activities that are not separately disclosed in the statement of cash flows (for example, cash received or cash paid during the current period for miscellaneous operating activities, net change during the reporting period in other assets or other liabilities).

+ References

No definition available.

+ Details

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

- Details

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- Details

Name:	us-gaap_DebtInstrumentAxis=csx_FixedRateNotesDueBetween2036And2040Member
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Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=csx_A325NotesDue2027Member
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- Details

Name:	us-gaap_DebtInstrumentAxis=csx_UnsecuredRevolvingCreditFacilityDue2028Member
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Period Type:

- Details

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Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=csx_FixedRateNotesDue2033Member
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Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=csx_FixedToFloatingInterestRateSwapMember
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- Details

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- Details

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- Details

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Debt and Credit Agreements - Narrative (Details)	3 Months Ended
Debt and Credit Agreements - Narrative (Details)	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($) swap	Sep. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Mar. 31, 2022 USD ($) swap	Dec. 31, 2020 USD ($)
Line of Credit Facility
Other operating activities	$ (15,000,000)				$ (31,000,000)
Commercial Paper
Line of Credit Facility
Maximum borrowing capacity of credit facility	1,000,000,000
Borrowings outstanding	0
Fixed Rate Notes Due Between 2036 and 2040
Line of Credit Facility
Debt issued	1,050,000,000	$ 1,050,000,000				$ 800,000,000
3.25% Notes Due 2027
Line of Credit Facility
Debt issued							$ 850,000,000
Debt interest rate							3.25%
Unsecured Revolving Credit Facility Due 2028 \| Credit Facility
Line of Credit Facility
Maximum borrowing capacity of credit facility	1,200,000,000
Borrowings outstanding	0
Fixed Rate Notes Due 2033
Line of Credit Facility
Debt issued		$ 250,000,000
Fixed-to-Floating Interest Rate Swap \| Fair Value Hedging
Line of Credit Facility
Derivative, number of fair value hedges \| swap						5
Derivative, term of contract (in years)						10 years
Two Separate Fixed-to-Floating Interest Rate Swaps \| Fair Value Hedging
Line of Credit Facility
Derivative, number of fair value hedges \| swap		2
Derivative, term of contract (in years)		10 years
Designated as Hedging Instrument \| Fixed-to-Floating Interest Rate Swap \| Fair Value Hedging
Line of Credit Facility
Fair value hedge derivative instrument liabilities at fair value	131,000,000	$ 107,000,000
Designated as Hedging Instrument \| Forward Starting Interest Rate Swap \| Cash Flow Hedge
Line of Credit Facility
Cash flow hedge derivative instrument assets at fair value	51,000,000	48,000,000
Designated as Hedging Instrument \| Interest Rate Swap \| Cash Flow Hedge
Line of Credit Facility
Aggregate notional value of interest forward interest rate swap	114,000,000	114,000,000					$ 500,000,000
Cash flow hedge derivative instrument assets at fair value	51,000,000	48,000,000
Derivative asset, notional amount settled			$ 113,000,000	$ 113,000,000
Other operating activities			$ 51,000,000	$ 44,000,000
Designated as Hedging Instrument \| Two Separate Fixed-to-Floating Interest Rate Swaps \| Fair Value Hedging
Line of Credit Facility
Interest rate fair value hedge asset at fair value	$ 11,000,000	$ 19,000,000