Summarized Consolidating Cash Flow Statements (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 28, 2012	Sep. 30, 2011
Operating Activities
Net Cash Provided by (Used in) Operating Activities	$ 2,304	$ 2,585
Investing Activities
Property Additions	(1,830)	(1,436)
Purchases of Short-term Investments	(78)	(14)
Proceeds from Sales of Short-term Investments	573	66
Other Investing Activities	10	(17)
Net Cash Used in Investing Activities	(1,325)	(1,401)
Financing Activities
Long-term Debt Issued	300	600
Long-term Debt Repaid	(481)	(595)
Dividends Paid	(415)	(354)
Stock Options Exercised	11	27
Shares Repurchased	(500)	(1,564)
Other Financing Activities	16	(10)
Net Cash Used in Financing Activities	(1,069)	(1,896)
Net Decrease in Cash and Cash Equivalents	(90)	(712)
Cash and Cash Equivalents at Beginning of Period	783	1,292
Cash and Cash Equivalents at End of Period	693	580
CSX Corporation [Member]
Operating Activities
Net Cash Provided by (Used in) Operating Activities	429	1,054
Investing Activities
Property Additions	0	0
Purchases of Short-term Investments	(50)	0
Proceeds from Sales of Short-term Investments	525	0
Other Investing Activities	(6)	(19)
Net Cash Used in Investing Activities	469	(19)
Financing Activities
Long-term Debt Issued	300	600
Long-term Debt Repaid	(400)	(507)
Dividends Paid	(415)	(354)
Stock Options Exercised	11	27
Shares Repurchased	(500)	(1,564)
Other Financing Activities	15	30
Net Cash Used in Financing Activities	(989)	(1,768)
Net Decrease in Cash and Cash Equivalents	(91)	(733)
Cash and Cash Equivalents at Beginning of Period	549	1,100
Cash and Cash Equivalents at End of Period	458	367
CSX Transportation [Member]
Operating Activities
Net Cash Provided by (Used in) Operating Activities	2,202	2,014
Investing Activities
Property Additions	(1,669)	(1,285)
Purchases of Short-term Investments	0	0
Proceeds from Sales of Short-term Investments	0	0
Other Investing Activities	78	(90)
Net Cash Used in Investing Activities	(1,591)	(1,375)
Financing Activities
Long-term Debt Issued	0	0
Long-term Debt Repaid	(79)	(86)
Dividends Paid	(536)	(510)
Stock Options Exercised	0	0
Shares Repurchased	0	0
Other Financing Activities	3	(21)
Net Cash Used in Financing Activities	(612)	(617)
Net Decrease in Cash and Cash Equivalents	(1)	22
Cash and Cash Equivalents at Beginning of Period	154	118
Cash and Cash Equivalents at End of Period	153	140
Eliminations and Other [Member]
Operating Activities
Net Cash Provided by (Used in) Operating Activities	(327)	(483)
Investing Activities
Property Additions	(161)	(151)
Purchases of Short-term Investments	(28)	(14)
Proceeds from Sales of Short-term Investments	48	66
Other Investing Activities	(62)	92
Net Cash Used in Investing Activities	(203)	(7)
Financing Activities
Long-term Debt Issued	0	0
Long-term Debt Repaid	(2)	(2)
Dividends Paid	536	510
Stock Options Exercised	0	0
Shares Repurchased	0	0
Other Financing Activities	(2)	(19)
Net Cash Used in Financing Activities	532	489
Net Decrease in Cash and Cash Equivalents	2	(1)
Cash and Cash Equivalents at Beginning of Period	80	74
Cash and Cash Equivalents at End of Period	$ 82	$ 73