Summarized Consolidating Financial Data (Income Statements) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 28, 2012	Sep. 28, 2012	Jun. 29, 2012	Mar. 30, 2012	Dec. 30, 2011	Sep. 30, 2011	Jul. 01, 2011	Apr. 01, 2011	Dec. 28, 2012	Dec. 30, 2011	Dec. 31, 2010
Consolidated Income Statement
Revenue	$ 2,884	$ 2,894	$ 3,012	$ 2,966	$ 2,951	$ 2,963	$ 3,019	$ 2,810	$ 11,756	$ 11,743	$ 10,636
Operating Expenses									8,299	8,325	7,565
Operating Income	804	854	943	856	841	878	926	773	3,457	3,418	3,071
Equity in Earnings of Subsidiaries									0	0	0
Interest Expense									(566)	(552)	(557)
Other Income - Net									73	22	32
Earnings Before Income Taxes									2,964	2,888	2,546
Income Tax Benefit (Expense)									(1,105)	(1,066)	(983)
Net Earnings	443	455	512	449	457	464	506	395	1,859	1,822	1,563
Total Comprehensive Earnings									1,798	1,718	1,601
CSX Corporation
Consolidated Income Statement
Revenue									0	0	0
Operating Expenses									(355)	(278)	(166)
Operating Income									355	278	166
Equity in Earnings of Subsidiaries									1,988	1,947	1,779
Interest Expense									(513)	(496)	(499)
Other Income - Net									(3)	2	13
Earnings Before Income Taxes									1,827	1,731	1,459
Income Tax Benefit (Expense)									32	91	104
Net Earnings									1,859	1,822	1,563
Total Comprehensive Earnings									1,798	1,718	1,601
CSX Transportation
Consolidated Income Statement
Revenue									11,689	11,676	9,939
Operating Expenses									8,779	8,679	7,110
Operating Income									2,910	2,997	2,829
Equity in Earnings of Subsidiaries									(2)	3	3
Interest Expense									(70)	(83)	(101)
Other Income - Net									61	19	22
Earnings Before Income Taxes									2,899	2,936	2,753
Income Tax Benefit (Expense)									(1,062)	(1,081)	(1,064)
Net Earnings									1,837	1,855	1,689
Total Comprehensive Earnings									1,814	1,841	1,701
Eliminations and Other
Consolidated Income Statement
Revenue									67	67	697
Operating Expenses									(125)	(76)	621
Operating Income									192	143	76
Equity in Earnings of Subsidiaries									(1,986)	(1,950)	(1,782)
Interest Expense									17	27	43
Other Income - Net									15	1	(3)
Earnings Before Income Taxes									(1,762)	(1,779)	(1,666)
Income Tax Benefit (Expense)									(75)	(76)	(23)
Net Earnings									(1,837)	(1,855)	(1,689)
Total Comprehensive Earnings									$ (1,814)	$ (1,841)	$ (1,701)