Stock Plans and Share-Based Compensation - Narrative (Details)	3 Months Ended
	Mar. 31, 2025 shares
Performance Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)	3 years
Performance Units | LTIP
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%
Performance Units | LTIP | 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)	0.20
Performance Units | LTIP | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout percentage range for participants	0.00%
Performance Units | LTIP | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout percentage range for participants	200.00%
Performance Units | LTIP | Maximum | Certain Executive Officers
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout percentage range for participants	240.00%
Stock Options | LTIP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)	3 years
Term of stock options (in years)	10 years
Restricted Stock Units | LTIP
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