Debt and Credit Agreements (Credit Facilities and Receivable Securitization Facility) (Details) (USD $)	12 Months Ended
	Dec. 26, 2014
Line of Credit Facility [Line Item]
Line of Credit Facility, Covenant Compliance	At December 2014, CSX was in compliance with all covenant requirements under the facilities.
Accounts Receivable Securitization Credit Facility [Member]
Line of Credit Facility [Line Item]
Line of credit facility, current borrowing capacity	250,000,000
Line of Credit Facility, Expiration Date	Jun. 20, 2017
Line of credit facility, amount outstanding	0
Line of Credit Facility Total Expiration Period	3 years
Unsecured Revolving Credit Facility, Current [Member]
Line of Credit Facility [Line Item]
Line of credit facility, current borrowing capacity	1,000,000,000
Line of credit facility, amount outstanding	0
Revolving Credit Facility [Member]
Line of Credit Facility [Line Item]
Line of Credit Facility, Expiration Date	Sep. 30, 2016