Summarized Consolidating Financial Data - Consolidating Income Statements (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 25, 2016
Consolidated Income Statement
Revenue	$ 2,869	$ 2,618
Expense	2,157	1,914
Operating Income	712	704
Equity in Earnings of Subsidiaries	0	0
Interest (Expense) / Benefit	(137)	(143)
Other Income / (Expense) - Net	7	7
Earnings Before Income Taxes	582	568
Income Tax Benefit / (Expense)	(220)	(212)
Net Earnings	362	356
Total Comprehensive Earnings	368	363
CSX Corporation
Consolidated Income Statement
Revenue	0	0
Expense	(48)	(72)
Operating Income	48	72
Equity in Earnings of Subsidiaries	422	401
Interest (Expense) / Benefit	(142)	(143)
Other Income / (Expense) - Net	3	1
Earnings Before Income Taxes	331	331
Income Tax Benefit / (Expense)	31	25
Net Earnings	362	356
Total Comprehensive Earnings	368	363
CSX Transportation
Consolidated Income Statement
Revenue	2,851	2,598
Expense	2,228	2,064
Operating Income	623	534
Equity in Earnings of Subsidiaries	0	0
Interest (Expense) / Benefit	(10)	(10)
Other Income / (Expense) - Net	11	7
Earnings Before Income Taxes	624	531
Income Tax Benefit / (Expense)	(235)	(198)
Net Earnings	389	333
Total Comprehensive Earnings	387	332
Eliminations and Other
Consolidated Income Statement
Revenue	18	20
Expense	(23)	(78)
Operating Income	41	98
Equity in Earnings of Subsidiaries	(422)	(401)
Interest (Expense) / Benefit	15	10
Other Income / (Expense) - Net	(7)	(1)
Earnings Before Income Taxes	(373)	(294)
Income Tax Benefit / (Expense)	(16)	(39)
Net Earnings	(389)	(333)
Total Comprehensive Earnings	$ (387)	$ (332)