Summarized Consolidating Financial Data (Income Statements) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 30, 2011	Sep. 30, 2011	Jul. 01, 2011	Apr. 01, 2011	Dec. 31, 2010	Sep. 24, 2010	Jun. 25, 2010	Mar. 26, 2010	Dec. 30, 2011	Dec. 31, 2010	Dec. 25, 2009
Consolidated Income Statement
Revenue	$ 2,951	$ 2,963	$ 3,019	$ 2,810	$ 2,816	$ 2,666	$ 2,663	$ 2,491	$ 11,743	$ 10,636	$ 9,041
Operating Expenses									8,325	7,565	6,771
Operating Income	841	878	926	773	846	825	768	632	3,418	3,071	2,270
Equity in Earnings of Subsidiaries									0	0	0
Interest Expense									(552)	(557)	(558)
Other Income - Net									22	32	34
Earnings Before Income Taxes									2,888	2,546	1,746
Income Tax Benefit (Expense)									(1,066)	(983)	(618)
Earnings from Continuing Operations									1,822	1,563	1,128
Discontinued Operations									0	0	15
Net Earnings	457	464	506	395	430	414	414	305	1,822	1,563	1,143
CSX Corporation
Consolidated Income Statement
Revenue									0	0	0
Operating Expenses									(278)	(166)	(279)
Operating Income									278	166	279
Equity in Earnings of Subsidiaries									1,947	1,779	1,239
Interest Expense									(496)	(499)	(500)
Other Income - Net									13	21	70
Earnings Before Income Taxes									1,742	1,467	1,088
Income Tax Benefit (Expense)									80	96	23
Earnings from Continuing Operations											1,111
Discontinued Operations											32
Net Earnings									1,822	1,563	1,143
CSX Transportation
Consolidated Income Statement
Revenue									11,676	9,939	7,776
Operating Expenses									8,679	7,110	5,983
Operating Income									2,997	2,829	1,793
Equity in Earnings of Subsidiaries									3	3	10
Interest Expense									(83)	(101)	(116)
Other Income - Net									19	22	18
Earnings Before Income Taxes									2,936	2,753	1,705
Income Tax Benefit (Expense)									(1,081)	(1,064)	(624)
Earnings from Continuing Operations											1,081
Discontinued Operations											0
Net Earnings									1,855	1,689	1,081
Eliminations and Other
Consolidated Income Statement
Revenue									67	697	1,265
Operating Expenses									(76)	621	1,067
Operating Income									143	76	198
Equity in Earnings of Subsidiaries									(1,950)	(1,782)	(1,249)
Interest Expense									27	43	58
Other Income - Net									(10)	(11)	(54)
Earnings Before Income Taxes									(1,790)	(1,674)	(1,047)
Income Tax Benefit (Expense)									(65)	(15)	(17)
Earnings from Continuing Operations											(1,064)
Discontinued Operations											(17)
Net Earnings									$ (1,855)	$ (1,689)	$ (1,081)