Summarized Consolidating Financial Data - Consolidating Income Statements (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Consolidated Income Statement
Revenue	$ 3,061		$ 3,102		$ 6,074	$ 5,978
Expense	1,756		1,819		3,550	3,651
Operating Income	1,305		1,283		2,524	2,327
Equity in Earnings of Subsidiaries	0		0		0	0
Interest (Expense) / Benefit	(184)		(157)		(362)	(306)
Other Income / (Expense) - Net	25		18		48	35
Earnings Before Income Taxes	1,146		1,144		2,210	2,056
Income Tax Benefit / (Expense)	(276)		(267)		(506)	(484)
Net Earnings	870	$ 834	877	$ 695	1,704	1,572
Total Comprehensive Earnings	874	$ 836	881	$ 596	1,710	1,477
Eliminations and Other
Consolidated Income Statement
Revenue	20		19		40	38
Expense	(52)		(45)		(89)	(78)
Operating Income	72		64		129	116
Equity in Earnings of Subsidiaries	(926)		(942)		(1,800)	(1,700)
Interest (Expense) / Benefit	48		32		97	56
Other Income / (Expense) - Net	(37)		(17)		(74)	(27)
Earnings Before Income Taxes	(843)		(863)		(1,648)	(1,555)
Income Tax Benefit / (Expense)	(17)		(19)		(33)	(31)
Net Earnings	(860)		(882)		(1,681)	(1,586)
Total Comprehensive Earnings	(859)		(881)		(1,678)	(1,581)
CSX Corporation
Consolidated Income Statement
Revenue	0		0		0	0
Expense	(138)		(84)		(275)	(162)
Operating Income	138		84		275	162
Equity in Earnings of Subsidiaries	926		942		1,800	1,700
Interest (Expense) / Benefit	(222)		(181)		(438)	(345)
Other Income / (Expense) - Net	11		6		19	10
Earnings Before Income Taxes	853		851		1,656	1,527
Income Tax Benefit / (Expense)	17		26		48	45
Net Earnings	870		877		1,704	1,572
Total Comprehensive Earnings	874		881		1,710	1,477
CSX Transportation
Consolidated Income Statement
Revenue	3,041		3,083		6,034	5,940
Expense	1,946		1,948		3,914	3,891
Operating Income	1,095		1,135		2,120	2,049
Equity in Earnings of Subsidiaries	0		0		0	0
Interest (Expense) / Benefit	(10)		(8)		(21)	(17)
Other Income / (Expense) - Net	51		29		103	52
Earnings Before Income Taxes	1,136		1,156		2,202	2,084
Income Tax Benefit / (Expense)	(276)		(274)		(521)	(498)
Net Earnings	860		882		1,681	1,586
Total Comprehensive Earnings	$ 859		$ 881		$ 1,678	$ 1,581