Summarized Consolidating Financial Data - Consolidating Income Statements (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 25, 2016	Mar. 27, 2015
Consolidated Income Statement
Revenue	$ 2,618	$ 3,027
Expense	1,914	2,184
Operating Income	704	843
Equity in Earnings of Subsidiaries	0	0
Interest (Expense) / Benefit	(143)	(134)
Other Income / (Expense) - Net	7	2
Earnings Before Income Taxes	568	711
Income Tax Benefit / (Expense)	(212)	(269)
Net Earnings	356	442
Total Comprehensive Earnings	363	440
CSX Corporation
Consolidated Income Statement
Revenue	0	0
Expense	(72)	(148)
Operating Income	72	148
Equity in Earnings of Subsidiaries	401	440
Interest (Expense) / Benefit	(143)	(133)
Other Income / (Expense) - Net	1	(1)
Earnings Before Income Taxes	331	454
Income Tax Benefit / (Expense)	25	(12)
Net Earnings	356	442
Total Comprehensive Earnings	363	440
CSX Transportation
Consolidated Income Statement
Revenue	2,598	3,007
Expense	2,064	2,344
Operating Income	534	663
Equity in Earnings of Subsidiaries	0	0
Interest (Expense) / Benefit	(10)	(7)
Other Income / (Expense) - Net	7	6
Earnings Before Income Taxes	531	662
Income Tax Benefit / (Expense)	(198)	(246)
Net Earnings	333	416
Total Comprehensive Earnings	332	413
Eliminations and Other
Consolidated Income Statement
Revenue	20	20
Expense	(78)	(12)
Operating Income	98	32
Equity in Earnings of Subsidiaries	(401)	(440)
Interest (Expense) / Benefit	10	6
Other Income / (Expense) - Net	(1)	(3)
Earnings Before Income Taxes	(294)	(405)
Income Tax Benefit / (Expense)	(39)	(11)
Net Earnings	(333)	(416)
Total Comprehensive Earnings	$ (332)	$ (413)