Summarized Consolidating Financial Data - Consolidating Income Statements (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Consolidated Income Statement
Revenues	$ 3,129	$ 2,743	$ 9,107	$ 8,545
Operating Expenses	1,836	1,875	5,487	5,951
Operating Income	1,293	868	3,620	2,594
Equity in Earnings of Subsidiaries	0	0	0	0
Interest (Expense) / Benefit	(162)	(132)	(468)	(406)
Other Income / (Expense) - Net	19	14	54	(29)
Earnings Before Income Taxes	1,150	750	3,206	2,159
Income Tax Benefit / (Expense)	(256)	(291)	(740)	(828)
Net Earnings	894	459	2,466	1,331
Total Comprehensive Earnings	901	467	2,378	1,410
Eliminations and Other
Consolidated Income Statement
Revenues	19	18	57	55
Operating Expenses	(30)	(27)	(108)	(103)
Operating Income	49	45	165	158
Equity in Earnings of Subsidiaries	(953)	(472)	(2,653)	(1,506)
Interest (Expense) / Benefit	39	18	95	47
Other Income / (Expense) - Net	(22)	(6)	(49)	(14)
Earnings Before Income Taxes	(887)	(415)	(2,442)	(1,315)
Income Tax Benefit / (Expense)	(17)	(18)	(48)	(64)
Net Earnings	(904)	(433)	(2,490)	(1,379)
Total Comprehensive Earnings	(903)	(433)	(2,484)	(1,378)
CSX Corporation
Consolidated Income Statement
Revenues	0	0	0	0
Operating Expenses	(86)	(129)	(248)	(171)
Operating Income	86	129	248	171
Equity in Earnings of Subsidiaries	953	472	2,653	1,506
Interest (Expense) / Benefit	(190)	(147)	(535)	(432)
Other Income / (Expense) - Net	6	1	16	6
Earnings Before Income Taxes	855	455	2,382	1,251
Income Tax Benefit / (Expense)	39	4	84	80
Net Earnings	894	459	2,466	1,331
Total Comprehensive Earnings	901	467	2,378	1,410
CSX Transportation
Consolidated Income Statement
Revenues	3,110	2,725	9,050	8,490
Operating Expenses	1,952	2,031	5,843	6,225
Operating Income	1,158	694	3,207	2,265
Equity in Earnings of Subsidiaries	0	0	0	0
Interest (Expense) / Benefit	(11)	(3)	(28)	(21)
Other Income / (Expense) - Net	35	19	87	(21)
Earnings Before Income Taxes	1,182	710	3,266	2,223
Income Tax Benefit / (Expense)	(278)	(277)	(776)	(844)
Net Earnings	904	433	2,490	1,379
Total Comprehensive Earnings	$ 903	$ 433	$ 2,484	$ 1,378