Summarized Consolidating Cash Flow Statements (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 29, 2013	Mar. 30, 2012
Operating Activities
Net Cash Provided by (Used in) Operating Activities	$ 731	$ 444
Investing Activities
Property Additions	(491)	(469)
Purchase of Short-term Investments	(290)	(53)
Proceeds from Sales of Short-term Investments	534	437
Other Investing Activities	(18)	8
Net Cash Used in Investing Activities	(265)	(77)
Financing Activities
Long-term Debt Issued	0	300
Long-term Debt Repaid	(413)	(413)
Dividends Paid	(143)	(125)
Stock Options Exercised	6	8
Shares Repurchased	0	(300)
Other Financing Activities	5	7
Net Cash Used in Financing Activities	(545)	(523)
Net Decrease in Cash and Cash Equivalents	(79)	(156)
Cash and Cash Equivalents at Beginning of Period	784	783
Cash and Cash Equivalents at End of Period	705	627
CSX Corporation [Member]
Operating Activities
Net Cash Provided by (Used in) Operating Activities	272	(23)
Investing Activities
Property Additions	0	0
Purchase of Short-term Investments	(285)	(50)
Proceeds from Sales of Short-term Investments	510	425
Other Investing Activities	0	1
Net Cash Used in Investing Activities	225	376
Financing Activities
Long-term Debt Issued		300
Long-term Debt Repaid	(400)	(400)
Dividends Paid	(143)	(125)
Stock Options Exercised	6	8
Shares Repurchased		(300)
Other Financing Activities	4	0
Net Cash Used in Financing Activities	(533)	(517)
Net Decrease in Cash and Cash Equivalents	(36)	(164)
Cash and Cash Equivalents at Beginning of Period	481	549
Cash and Cash Equivalents at End of Period	445	385
CSX Transportation [Member]
Operating Activities
Net Cash Provided by (Used in) Operating Activities	689	641
Investing Activities
Property Additions	(458)	(435)
Purchase of Short-term Investments	0	0
Proceeds from Sales of Short-term Investments	0	0
Other Investing Activities	(63)	(13)
Net Cash Used in Investing Activities	(521)	(448)
Financing Activities
Long-term Debt Issued		0
Long-term Debt Repaid	(13)	(13)
Dividends Paid	(182)	(179)
Stock Options Exercised	0	0
Shares Repurchased		0
Other Financing Activities	0	4
Net Cash Used in Financing Activities	(195)	(188)
Net Decrease in Cash and Cash Equivalents	(27)	5
Cash and Cash Equivalents at Beginning of Period	235	154
Cash and Cash Equivalents at End of Period	208	159
Eliminations and Other [Member]
Operating Activities
Net Cash Provided by (Used in) Operating Activities	(230)	(174)
Investing Activities
Property Additions	(33)	(34)
Purchase of Short-term Investments	(5)	(3)
Proceeds from Sales of Short-term Investments	24	12
Other Investing Activities	45	20
Net Cash Used in Investing Activities	31	(5)
Financing Activities
Long-term Debt Issued		0
Long-term Debt Repaid	0	0
Dividends Paid	182	179
Stock Options Exercised	0	0
Shares Repurchased		0
Other Financing Activities	1	3
Net Cash Used in Financing Activities	183	182
Net Decrease in Cash and Cash Equivalents	(16)	3
Cash and Cash Equivalents at Beginning of Period	68	80
Cash and Cash Equivalents at End of Period	$ 52	$ 83