Summarized Consolidating Financial Data - Consolidating Income Statements (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Consolidated Income Statement
Revenue	$ 2,978			$ 3,129			$ 9,052	$ 9,107
Expense	1,691			1,836			5,241	5,487
Operating Income	1,287			1,293			3,811	3,620
Equity in Earnings of Subsidiaries	0			0			0	0
Interest (Expense) / Benefit	(186)			(162)			(548)	(468)
Other Income / (Expense) - Net	24			19			72	54
Earnings Before Income Taxes	1,125			1,150			3,335	3,206
Income Tax Benefit / (Expense)	(269)			(256)			(775)	(740)
Net Earnings	856	$ 870	$ 834	894	$ 877	$ 695	2,560	2,466
Total Comprehensive Earnings	863	$ 874	$ 836	901	$ 881	$ 596	2,573	2,378
Eliminations and Other
Consolidated Income Statement
Revenue	20			19			60	57
Expense	(33)			(30)			(122)	(108)
Operating Income	53			49			182	165
Equity in Earnings of Subsidiaries	(883)			(953)			(2,683)	(2,653)
Interest (Expense) / Benefit	45			39			142	95
Other Income / (Expense) - Net	(32)			(22)			(106)	(49)
Earnings Before Income Taxes	(817)			(887)			(2,465)	(2,442)
Income Tax Benefit / (Expense)	(48)			(17)			(81)	(48)
Net Earnings	(865)			(904)			(2,546)	(2,490)
Total Comprehensive Earnings	(864)			(903)			(2,542)	(2,484)
CSX Corporation
Consolidated Income Statement
Revenue	0			0			0	0
Expense	(138)			(86)			(413)	(248)
Operating Income	138			86			413	248
Equity in Earnings of Subsidiaries	883			953			2,683	2,653
Interest (Expense) / Benefit	(220)			(190)			(658)	(535)
Other Income / (Expense) - Net	9			6			28	16
Earnings Before Income Taxes	810			855			2,466	2,382
Income Tax Benefit / (Expense)	46			39			94	84
Net Earnings	856			894			2,560	2,466
Total Comprehensive Earnings	863			901			2,573	2,378
CSX Transportation
Consolidated Income Statement
Revenue	2,958			3,110			8,992	9,050
Expense	1,862			1,952			5,776	5,843
Operating Income	1,096			1,158			3,216	3,207
Equity in Earnings of Subsidiaries	0			0			0	0
Interest (Expense) / Benefit	(11)			(11)			(32)	(28)
Other Income / (Expense) - Net	47			35			150	87
Earnings Before Income Taxes	1,132			1,182			3,334	3,266
Income Tax Benefit / (Expense)	(267)			(278)			(788)	(776)
Net Earnings	865			904			2,546	2,490
Total Comprehensive Earnings	$ 864			$ 903			$ 2,542	$ 2,484