Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 28, 2012		Dec. 30, 2011		Dec. 31, 2010
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Comprehensive Earnings	$ 1,798		$ 1,718		$ 1,601
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	(875)		(771)		(809)
Other Comprehensive Income (Loss):
Income (Loss) Before Reclassifications	(181)		(229)		(12)
Loss (Income) Reclassified to Net Earnings	87		74		62
Tax (Expense) Benefit	33		51		(12)
Total Other Comprehensive (Loss) Income	(61)		(104)		38
Ending Balance	(936)		(875)		(771)
Pension and Other Post-Employment Benefits [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	(799)		(711)		(737)
Other Comprehensive Income (Loss):
Income (Loss) Before Reclassifications	(172)		(216)		(24)
Loss (Income) Reclassified to Net Earnings	88		75		63
Tax (Expense) Benefit	32		53		(13)
Total Other Comprehensive (Loss) Income	(52)		(88)		26
Ending Balance	(851)		(799)		(711)
Other [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	(76)	[1]	(60)	[1]	(72)	[1]
Other Comprehensive Income (Loss):
Income (Loss) Before Reclassifications	(9)	[1]	(13)	[1]	12	[1]
Loss (Income) Reclassified to Net Earnings	(1)	[1]	(1)	[1]	(1)	[1]
Tax (Expense) Benefit	1	[1]	(2)	[1]	1	[1]
Total Other Comprehensive (Loss) Income	(9)	[1]	(16)	[1]	12	[1]
Ending Balance	$ (85)	[1]	$ (76)	[1]	$ (60)	[1]

[1] Other primarily represents CSX's share of AOCI of equity method investees.