Summarized Consolidating Financial Data - Consolidating Income Statements (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Consolidated Income Statement
Revenues	$ 3,102	$ 2,933	$ 5,978	$ 5,802
Operating Expenses	1,819	1,976	3,651	4,076
Operating Income	1,283	957	2,327	1,726
Equity in Earnings of Subsidiaries	0	0	0	0
Interest (Expense) / Benefit	(157)	(137)	(306)	(274)
Other Income / (Expense) - Net	18	7	35	(43)
Earnings Before Income Taxes	1,144	827	2,056	1,409
Income Tax Benefit / (Expense)	(267)	(317)	(484)	(537)
Net Earnings	877	510	1,572	872
Total Comprehensive Earnings	881	575	1,477	943
Eliminations and Other
Consolidated Income Statement
Revenues	19	19	38	37
Operating Expenses	(45)	(54)	(78)	(76)
Operating Income	64	73	116	113
Equity in Earnings of Subsidiaries	(942)	(612)	(1,700)	(1,034)
Interest (Expense) / Benefit	32	14	56	29
Other Income / (Expense) - Net	(17)	(2)	(27)	(8)
Earnings Before Income Taxes	(863)	(527)	(1,555)	(900)
Income Tax Benefit / (Expense)	(19)	(30)	(31)	(46)
Net Earnings	(882)	(557)	(1,586)	(946)
Total Comprehensive Earnings	(881)	(558)	(1,581)	(945)
CSX Corporation
Consolidated Income Statement
Revenues	0	0	0	0
Operating Expenses	(84)	6	(162)	(42)
Operating Income	84	(6)	162	42
Equity in Earnings of Subsidiaries	942	612	1,700	1,034
Interest (Expense) / Benefit	(181)	(143)	(345)	(285)
Other Income / (Expense) - Net	6	2	10	5
Earnings Before Income Taxes	851	465	1,527	796
Income Tax Benefit / (Expense)	26	45	45	76
Net Earnings	877	510	1,572	872
Total Comprehensive Earnings	881	575	1,477	943
CSX Transportation
Consolidated Income Statement
Revenues	3,083	2,914	5,940	5,765
Operating Expenses	1,948	2,024	3,891	4,194
Operating Income	1,135	890	2,049	1,571
Equity in Earnings of Subsidiaries	0	0	0	0
Interest (Expense) / Benefit	(8)	(8)	(17)	(18)
Other Income / (Expense) - Net	29	7	52	(40)
Earnings Before Income Taxes	1,156	889	2,084	1,513
Income Tax Benefit / (Expense)	(274)	(332)	(498)	(567)
Net Earnings	882	557	1,586	946
Total Comprehensive Earnings	$ 881	$ 558	$ 1,581	$ 945