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Stock Plans and Share-Based Compensation - Narrative (Details) | 8 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Dec. 31, 2018 | Dec. 31, 2023 USD ($) plan shares | Dec. 31, 2022 plan | Dec. 31, 2021 plan | May 31, 2018 USD ($) shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Period prior to grant date |  | 3 years |  |  |
Performance Units |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Unrecognized compensation cost |  | $ 20,000,000 |  |  |
Look-back period |  | 2 years 9 months 18 days | 2 years 8 months 12 days | 2 years 10 months 24 days |
Expected weighted average period of recognition for unrecognized compensation cost (in years) |  | 2 years |  |  |
Stock Options |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Unrecognized compensation cost |  | $ 28,000,000 |  |  |
Expected weighted average period of recognition for unrecognized compensation cost (in years) |  | 2 years |  |  |
Restricted Stock Units |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Award performance period |  | 3 years |  |  |
Restricted Stock |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Award performance period |  | 5 years |  |  |
Restricted Stock | Share-Based Payment Arrangement, Cliff Vesting |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Award performance period |  | 3 years |  |  |
Restricted Stock | Share-Based Payment Arrangement, Graduated Vesting |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Award performance period |  | 3 years |  |  |
Stock Options |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Unrecognized compensation cost |  | $ 12,000,000 |  |  |
Look-back period |  | 6 years | 6 years | 6 years |
Expected weighted average period of recognition for unrecognized compensation cost (in years) |  | 2 years |  |  |
Non-management Directors |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Annual retainer to be paid to non-management directors, cash option |  | $ 130,000 |  |  |
Annual retainer to be paid to non-management directors, common stock option |  | 180,000 |  |  |
Chairman |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Annual grant of common stock amount |  | $ 250,000 |  |  |
LITP | Minimum |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Payout range (as a percent) |  | 0.00% |  |  |
LITP | Maximum |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Payout range (as a percent) |  | 200.00% |  |  |
LITP | Performance Units |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Number of equivalent shares of CSX common stock per unit of award (in shares) | shares |  | 1 |  |  |
Award performance period |  | 3 years |  |  |
Number of long term incentive plans | plan |  | 3 | 3 | 3 |
LITP | Stock Options |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Number of equivalent shares of CSX common stock per unit of award (in shares) | shares |  | 1 |  |  |
LITP | Restricted Stock |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Number of equivalent shares of CSX common stock per unit of award (in shares) | shares |  | 1 |  |  |
LITP | Stock Options |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Award term |  | 10 years |  |  |
LITP | Stock Options | Vesting on anniversary of the grant date (graded period) |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Award performance period |  | 3 years |  |  |
LITP | Certain Executive Officers | Performance Units | Minimum |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Percentage of payout subject to adjustment |  | 25.00% |  |  |
LITP | Certain Executive Officers | Performance Units | Maximum |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Percentage of payout subject to adjustment |  | 250.00% |  |  |
2021-2023 LTIP | Performance Units |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Award performance period |  | 3 years | 3 years | 3 years |
Percentage payout on operating ratio |  | 50.00% |  |  |
2020-2022 LTIP | Performance Units |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Award performance period |  | 3 years | 3 years | 3 years |
2019-2021 LTIP | Performance Units |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Award performance period |  | 3 years | 3 years | 3 years |
ESPP | Employee Stock Purchase Plan |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Number of registered shares of common stock that my be issued pursuant to plan (in shares) | shares |  |  |  |  | 12,000,000
Employee contribution percentage, minimum |  |  |  |  | 1.00%
Employee contribution percentage, maximum |  |  |  |  | 10.00%
Maximum value of stocks purchased by employee, after tax |  |  |  |  | $ 25,000
Percentage of share closing market price | 85.00% |  |  |  |
Share offering period | 6 months |  |  |  |

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