Related Party Transactions (Consolidated Balance Sheets Components) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 30, 2011		Dec. 31, 2010		Dec. 25, 2009
Corporate Joint Venture [Member] | Accounts Payable [Member]
Related Party Transaction [Line Items]
CSX Payable to Conrail	$ 143	[1]	$ 119	[1]
Subsidiaries [Member]
Related Party Transaction [Line Items]
Interest Expense Related to Conrail	4		4		4
Subsidiaries [Member] | 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]
Promissory notes interest rates	4.40%
Subsidiaries [Member] | 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]
Promissory notes interest rates	4.52%

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

[2] Included on the consolidated balance sheet of CSX as long-term debt.