Stock Plans and Share-Based Compensation - Narrative (Details)	3 Months Ended
Mar. 31, 2024 shares
Performance Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)	3 years
LTIP \| Performance Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of grants with performance vesting, average annual operating income growth	0.50
Percentage of grants with performance vesting, cumulative free cash flow	50.00%
LTIP \| Performance Units \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout percentage range for participants	0.00%
LTIP \| Performance Units \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout percentage range for participants	200.00%
LTIP \| Performance Units \| Certain Executive Officers
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of payout subject to upward or downward adjustment (up to)	0.25
LTIP \| Performance Units \| Certain Executive Officers \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout percentage range for participants	250.00%
LTIP \| Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of stock options (in years)	10 years
Award vesting period (in years)	3 years
LTIP \| Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)	3 years
Number of equivalent shares of CSX common stock per unit of award (in shares)	1

Percentage Of Grants With Performance Vesting, Average Annual Operating Income Growth

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Percentage Of Grants With Performance Vesting, CSX Cash Earnings

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- Definition

Share Based Compensation Arrangement by Share Based Payment Award, Equity Instruments Other than Options, Payout Percentage Adjustment

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- Definition

Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Equivalent Shares of Common Stock Per Unit

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Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other Than Options, Payout Percentage of Target

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- Definition

Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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- 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.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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