Summarized Consolidating Financial Data (Cash Flow Statements) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 30, 2011	Dec. 31, 2010	Dec. 25, 2009
Operating Activities
Net Cash Provided by (Used in) Operating Activities	$ 3,491	$ 3,261	$ 2,039
Investing Activities
Property Additions	(2,297)	(1,840)	(1,426)
Payments to Acquire Short-term Investments	(492)	0	0
Proceeds from Property Dispositions	240	108	45
Other Investing Activities	(38)	(39)	9
Net Cash Used in Investing Activities	(2,587)	(1,771)	(1,372)
Financing Activities
Long-term Debt Issued	1,200	800	500
Long-term Debt Repaid	(605)	(113)	(323)
Dividends Paid	(480)	(372)	(345)
Stock Options Exercised	29	42	34
Shares Repurchased	(1,564)	(1,452)	0
Other Financing Activities	7	(132)	(173)
Net Cash (Used in) Provided by Financing Activities	(1,413)	(1,227)	(307)
Net Decrease in Cash and Cash Equivalents	(509)	263	360
Cash and Cash Equivalents at Beginning of Period	1,292	1,029	669
Cash and Cash Equivalents at End of Period	783	1,292	1,029
CSX Corporation
Operating Activities
Net Cash Provided by (Used in) Operating Activities	1,231	944	436
Investing Activities
Property Additions	0	0	0
Payments to Acquire Short-term Investments	(475)
Proceeds from Property Dispositions	0	0	2
Other Investing Activities	(20)	301	(89)
Net Cash Used in Investing Activities	(495)	301	(87)
Financing Activities
Long-term Debt Issued	1,200	800	500
Long-term Debt Repaid	(507)	0	(200)
Dividends Paid	(480)	(372)	(345)
Stock Options Exercised	29	42	34
Shares Repurchased	(1,564)	(1,452)
Other Financing Activities	35	(81)	21
Net Cash (Used in) Provided by Financing Activities	(1,287)	(1,063)	10
Net Decrease in Cash and Cash Equivalents	(551)	182	359
Cash and Cash Equivalents at Beginning of Period	1,100	918	559
Cash and Cash Equivalents at End of Period	549	1,100	918
CSX Transportation
Operating Activities
Net Cash Provided by (Used in) Operating Activities	2,746	2,393	2,920
Investing Activities
Property Additions	(2,034)	(1,587)	(1,331)
Payments to Acquire Short-term Investments	0
Proceeds from Property Dispositions	239	107	42
Other Investing Activities	(133)	(110)	(402)
Net Cash Used in Investing Activities	(1,928)	(1,590)	(1,691)
Financing Activities
Long-term Debt Issued	0	0	0
Long-term Debt Repaid	(95)	(111)	(120)
Dividends Paid	(680)	(590)	(475)
Stock Options Exercised	0	0	0
Shares Repurchased	0	0
Other Financing Activities	(7)	(14)	(667)
Net Cash (Used in) Provided by Financing Activities	(782)	(715)	(1,262)
Net Decrease in Cash and Cash Equivalents	36	88	(33)
Cash and Cash Equivalents at Beginning of Period	118	30	63
Cash and Cash Equivalents at End of Period	154	118	30
Eliminations and Other
Operating Activities
Net Cash Provided by (Used in) Operating Activities	(486)	(76)	(1,317)
Investing Activities
Property Additions	(263)	(253)	(95)
Payments to Acquire Short-term Investments	(17)
Proceeds from Property Dispositions	1	1	1
Other Investing Activities	115	(230)	500
Net Cash Used in Investing Activities	(164)	(482)	406
Financing Activities
Long-term Debt Issued	0	0	0
Long-term Debt Repaid	(3)	(2)	(3)
Dividends Paid	680	590	475
Stock Options Exercised	0	0	0
Shares Repurchased	0	0
Other Financing Activities	(21)	(37)	473
Net Cash (Used in) Provided by Financing Activities	656	551	945
Net Decrease in Cash and Cash Equivalents	6	(7)	34
Cash and Cash Equivalents at Beginning of Period	74	81	47
Cash and Cash Equivalents at End of Period	$ 80	$ 74	$ 81