Summarized Consolidating Financial Data - Consolidating Income Statement (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 26, 2015	Jun. 27, 2014	Jun. 26, 2015	Jun. 27, 2014
Consolidated Income Statement
Revenue	$ 3,064	$ 3,244	$ 6,091	$ 6,256
Expense	2,047	2,247	4,231	4,520
Operating Income	1,017	997	1,860	1,736
Equity in Earnings of Subsidiaries	0	0	0	0
Interest (Expense) / Benefit	(134)	(135)	(268)	(275)
Other Income / (Expense) - Net	4	(12)	6	(5)
Earnings Before Income Taxes	887	850	1,598	1,456
Income Tax Benefit / (Expense)	(334)	(321)	(603)	(529)
Net Earnings	553	529	995	927
Total Comprehensive Earnings	565	544	1,005	958
CSX Corporation
Consolidated Income Statement
Revenue	0	0	0	0
Expense	(146)	(105)	(294)	(208)
Operating Income	146	105	294	208
Equity in Earnings of Subsidiaries	546	545	986	961
Interest (Expense) / Benefit	(132)	(126)	(265)	(256)
Other Income / (Expense) - Net	(2)	(3)	(3)	(5)
Earnings Before Income Taxes	558	521	1,012	908
Income Tax Benefit / (Expense)	(5)	8	(17)	19
Net Earnings	553	529	995	927
Total Comprehensive Earnings	565	544	1,005	958
CSX Transportation
Consolidated Income Statement
Revenue	3,045	3,223	6,052	6,215
Expense	2,239	2,360	4,583	4,753
Operating Income	806	863	1,469	1,462
Equity in Earnings of Subsidiaries	0	0	0	0
Interest (Expense) / Benefit	(9)	(14)	(16)	(28)
Other Income / (Expense) - Net	7	(10)	13	(4)
Earnings Before Income Taxes	804	839	1,466	1,430
Income Tax Benefit / (Expense)	(305)	(318)	(551)	(522)
Net Earnings	499	521	915	908
Total Comprehensive Earnings	499	522	912	915
Eliminations and Other
Consolidated Income Statement
Revenue	19	21	39	41
Expense	(46)	(8)	(58)	(25)
Operating Income	65	29	97	66
Equity in Earnings of Subsidiaries	(546)	(545)	(986)	(961)
Interest (Expense) / Benefit	7	5	13	9
Other Income / (Expense) - Net	(1)	1	(4)	4
Earnings Before Income Taxes	(475)	(510)	(880)	(882)
Income Tax Benefit / (Expense)	(24)	(11)	(35)	(26)
Net Earnings	(499)	(521)	(915)	(908)
Total Comprehensive Earnings	$ (499)	$ (522)	$ (912)	$ (915)