Document And Entity Information	3 Months Ended
	Mar. 30, 2012
Entity Information
Entity Registrant Name	CSX CORP
Entity Central Index Key	0000277948
Current Fiscal Year End Date	--12-28
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	1,039,158,062
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q1
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 30, 2012