Summarized Consolidating Cash Flow Statements (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 26, 2014	Sep. 27, 2013
Operating Activities
Net Cash Provided by (Used in) Operating Activities	$ 2,302	$ 2,499
Investing Activities
Property Additions	(1,557)	(1,687)
Purchase of Short-term Investments	(1,170)	(809)
Proceeds from Sales of Short-term Investments	1,102	1,307
Other Investing Activities	5	(54)
Net Cash Provided by (Used in) Investing Activities	(1,620)	(1,243)
Financing Activities
Long-term Debt Issued	1,000	0
Long-term Debt Repaid	(932)	(779)
Dividends Paid	(470)	(448)
Stock Options Exercised	0	9
Shares Repurchased	(388)	(224)
Other Financing Activities	(5)	(7)
Net Cash Used in Financing Activities	(795)	(1,449)
Net Decrease in Cash and Cash Equivalents	(113)	(193)
Cash and Cash Equivalents at Beginning of Period	592	784
Cash and Cash Equivalents at End of Period	479	591
CSX Corporation
Operating Activities
Net Cash Provided by (Used in) Operating Activities	397	871
Investing Activities
Property Additions	0	0
Purchase of Short-term Investments	(1,170)	(805)
Proceeds from Sales of Short-term Investments	1,077	1,240
Other Investing Activities	0	(4)
Net Cash Provided by (Used in) Investing Activities	(93)	431
Financing Activities
Long-term Debt Issued	1,000
Long-term Debt Repaid	(600)	(700)
Dividends Paid	(470)	(448)
Stock Options Exercised		9
Shares Repurchased	(388)	(224)
Other Financing Activities	10	12
Net Cash Used in Financing Activities	(448)	(1,351)
Net Decrease in Cash and Cash Equivalents	(144)	(49)
Cash and Cash Equivalents at Beginning of Period	439	481
Cash and Cash Equivalents at End of Period	295	432
CSX Transportation
Operating Activities
Net Cash Provided by (Used in) Operating Activities	2,301	2,106
Investing Activities
Property Additions	(1,398)	(1,522)
Purchase of Short-term Investments	0	0
Proceeds from Sales of Short-term Investments	0	0
Other Investing Activities	(90)	(76)
Net Cash Provided by (Used in) Investing Activities	(1,488)	(1,598)
Financing Activities
Long-term Debt Issued	0
Long-term Debt Repaid	(332)	(79)
Dividends Paid	(428)	(548)
Stock Options Exercised		0
Shares Repurchased	0	0
Other Financing Activities	(16)	(15)
Net Cash Used in Financing Activities	(776)	(642)
Net Decrease in Cash and Cash Equivalents	37	(134)
Cash and Cash Equivalents at Beginning of Period	91	235
Cash and Cash Equivalents at End of Period	128	101
Eliminations and Other
Operating Activities
Net Cash Provided by (Used in) Operating Activities	(396)	(478)
Investing Activities
Property Additions	(159)	(165)
Purchase of Short-term Investments	0	(4)
Proceeds from Sales of Short-term Investments	25	67
Other Investing Activities	95	26
Net Cash Provided by (Used in) Investing Activities	(39)	(76)
Financing Activities
Long-term Debt Issued	0
Long-term Debt Repaid	0	0
Dividends Paid	428	548
Stock Options Exercised		0
Shares Repurchased	0	0
Other Financing Activities	1	(4)
Net Cash Used in Financing Activities	429	544
Net Decrease in Cash and Cash Equivalents	(6)	(10)
Cash and Cash Equivalents at Beginning of Period	62	68
Cash and Cash Equivalents at End of Period	$ 56	$ 58