Debt and Credit Agreements (Details) (USD $)	3 Months Ended	9 Months Ended
	Mar. 30, 2012	Sep. 28, 2012
Movement, Debt Instruments [Roll Forward]
Current Portion	$ 507,000,000	$ 507,000,000
Long-term Portion	8,734,000,000	8,734,000,000
Long-term Debt	9,241,000,000	9,241,000,000
Long-term debt repaid		(481,000,000)
Reclassifications		0
Debt conversions to CSX stock		(1,000,000)
Discount and premium activity		(4,000,000)
Current Portion		806,000,000
Long-term Debt Portion		8,257,000,000
Long-term Debt		9,063,000,000
Employer contribution to qualified pension plans	275,000,000
Notes Payable [Member]
Movement, Debt Instruments [Roll Forward]
Long-term debt issued / Capital lease additions		300,000,000
Notes Payable [Member] | 4.4% Notes Due 2043 [Member]
Movement, Debt Instruments [Roll Forward]
Notes issued, face amount	300,000,000
Notes issued, interest rate	4.40%
Capital Lease Obligations [Member]
Movement, Debt Instruments [Roll Forward]
Long-term debt issued / Capital lease additions		8,000,000
Current Liabilities [Member]
Movement, Debt Instruments [Roll Forward]
Current Portion	507,000,000	507,000,000
Long-term debt repaid		(481,000,000)
Reclassifications		781,000,000
Debt conversions to CSX stock		(1,000,000)
Discount and premium activity		0
Current Portion		806,000,000
Current Liabilities [Member] | Notes Payable [Member]
Movement, Debt Instruments [Roll Forward]
Long-term debt issued / Capital lease additions		0
Current Liabilities [Member] | Capital Lease Obligations [Member]
Movement, Debt Instruments [Roll Forward]
Long-term debt issued / Capital lease additions		0
Long Term Liabilities [Member]
Movement, Debt Instruments [Roll Forward]
Long-term Portion	8,734,000,000	8,734,000,000
Long-term debt repaid		0
Reclassifications		(781,000,000)
Debt conversions to CSX stock		0
Discount and premium activity		(4,000,000)
Long-term Debt Portion		8,257,000,000
Long Term Liabilities [Member] | Notes Payable [Member]
Movement, Debt Instruments [Roll Forward]
Long-term debt issued / Capital lease additions		300,000,000
Long Term Liabilities [Member] | Capital Lease Obligations [Member]
Movement, Debt Instruments [Roll Forward]
Long-term debt issued / Capital lease additions		$ 8,000,000