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