Debt and Credit Agreements (Details) (USD $)	3 Months Ended	6 Months Ended
	Mar. 30, 2012	Jun. 29, 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		(455,000,000)
Reclassifications		0
Debt conversions to CSX stock		(1,000,000)
Discount and premium activity		(3,000,000)
Current Portion		508,000,000
Long-term Debt Portion		8,581,000,000
Long-term Debt		9,089,000,000
Employer contribution to qualified pension plans	275,000,000
Notes Payable
Movement, Debt Instruments [Roll Forward]
Long-term debt issued / Capital lease additions		300,000,000
Notes Payable | 4.4% Notes Due 2043
Movement, Debt Instruments [Roll Forward]
Notes issued, face amount	300,000,000
Notes issued, interest rate	4.40%
Capital Lease Obligations
Movement, Debt Instruments [Roll Forward]
Long-term debt issued / Capital lease additions		7,000,000
Current Liabilities
Movement, Debt Instruments [Roll Forward]
Current Portion	507,000,000	507,000,000
Long-term debt repaid		(455,000,000)
Reclassifications		457,000,000
Debt conversions to CSX stock		(1,000,000)
Discount and premium activity		0
Current Portion		508,000,000
Current Liabilities | Notes Payable
Movement, Debt Instruments [Roll Forward]
Long-term debt issued / Capital lease additions		0
Current Liabilities | Capital Lease Obligations
Movement, Debt Instruments [Roll Forward]
Long-term debt issued / Capital lease additions		0
Long Term Liabilities
Movement, Debt Instruments [Roll Forward]
Long-term Portion	8,734,000,000	8,734,000,000
Long-term debt repaid		0
Reclassifications		(457,000,000)
Debt conversions to CSX stock		0
Discount and premium activity		(3,000,000)
Long-term Debt Portion		8,581,000,000
Long Term Liabilities | Notes Payable
Movement, Debt Instruments [Roll Forward]
Long-term debt issued / Capital lease additions		300,000,000
Long Term Liabilities | Capital Lease Obligations
Movement, Debt Instruments [Roll Forward]
Long-term debt issued / Capital lease additions		$ 7,000,000