Related Party Transactions (Consolidated Balance Sheets Components) (Details) (Corporate Joint Venture [Member], USD $) In Millions, unless otherwise specified	Dec. 28, 2012		Dec. 30, 2011
Accounts Payable [Member]
Related Party Transaction [Line Items]
CSX Payable to Conrail	$ 175	[1]	$ 143	[1]
Long-term Debt [Member] | Promissory Note Related Party October 2035 [Member]
Related Party Transaction [Line Items]
Promissory Notes Payable to Conrail Subsidiary	73	[2]	73	[2]
Notes issued, interest rate	4.40%
Long-term Debt [Member] | Promissory Note Related Party March 2035 [Member]
Related Party Transaction [Line Items]
Promissory Notes Payable to Conrail Subsidiary	$ 23	[2]	$ 23	[2]
Notes issued, interest rate	4.52%

[1] CSX Payable to Conrail is included on the consolidated balance sheet of CSX as accounts payable because it is short term in nature.

[2] Promissory notes payable to Conrail are included on the consolidated balance sheet of CSX as long-term debt.