Document And Entity Information	3 Months Ended
	Mar. 31, 2019 shares
Document and Entity Information [Abstract]
Entity Registrant Name	CSX CORP
Entity Central Index Key	0000277948
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	809,163,666
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2019
Entity Emerging Growth Company	false
Entity Small Business	false