Stock Plans and Share-Based Compensation - Assumptions and Inputs Used to Estimate Fair Value of Stock Options (Details) - Stock Options - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant date fair value (in dollars per share)	$ 9.82	$ 10.12	$ 7.94
Annual dividend yield	1.40%	1.10%	1.20%
Risk-free Interest Rate	3.80%	2.00%	0.70%
Annualized Volatility	29.60%	30.10%	31.20%
Expected Life (in years)	6 years	6 years	6 years
Weighted-average grant-date market price of CSX stock (strike price) (in dollars per share)	$ 31.54	$ 35.12	$ 29.65