Summarized Consolidating Financial Data - Consolidating Income Statements (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 24, 2016	Jun. 30, 2017	Jun. 24, 2016
Consolidated Income Statement
Revenue	$ 2,933	$ 2,704	$ 5,802	$ 5,322
Expense	1,975	1,864	4,132	3,778
Operating Income	958	840	1,670	1,544
Equity in Earnings of Subsidiaries	0	0	0	0
Interest (Expense) / Benefit	(137)	(141)	(274)	(284)
Other Income / (Expense) - Net	6	8	13	15
Earnings Before Income Taxes	827	707	1,409	1,275
Income Tax Benefit / (Expense)	(317)	(262)	(537)	(474)
Net Earnings	510	445	872	801
Total Comprehensive Earnings	575	454	943	817
Eliminations and Other
Consolidated Income Statement
Revenue	19	19	37	39
Expense	(56)	(30)	(79)	(108)
Operating Income	75	49	116	147
Equity in Earnings of Subsidiaries	(612)	(493)	(1,034)	(894)
Interest (Expense) / Benefit	14	10	29	20
Other Income / (Expense) - Net	(4)	0	(11)	(1)
Earnings Before Income Taxes	(527)	(434)	(900)	(728)
Income Tax Benefit / (Expense)	(30)	(19)	(46)	(58)
Net Earnings	(557)	(453)	(946)	(786)
Total Comprehensive Earnings	(558)	(454)	(945)	(786)
CSX Corporation
Consolidated Income Statement
Revenue	0	0	0	0
Expense	6	(67)	(42)	(139)
Operating Income	(6)	67	42	139
Equity in Earnings of Subsidiaries	612	493	1,034	894
Interest (Expense) / Benefit	(143)	(141)	(285)	(284)
Other Income / (Expense) - Net	2	0	5	1
Earnings Before Income Taxes	465	419	796	750
Income Tax Benefit / (Expense)	45	26	76	51
Net Earnings	510	445	872	801
Total Comprehensive Earnings	575	454	943	817
CSX Transportation
Consolidated Income Statement
Revenue	2,914	2,685	5,765	5,283
Expense	2,025	1,961	4,253	4,025
Operating Income	889	724	1,512	1,258
Equity in Earnings of Subsidiaries	0	0	0	0
Interest (Expense) / Benefit	(8)	(10)	(18)	(20)
Other Income / (Expense) - Net	8	8	19	15
Earnings Before Income Taxes	889	722	1,513	1,253
Income Tax Benefit / (Expense)	(332)	(269)	(567)	(467)
Net Earnings	557	453	946	786
Total Comprehensive Earnings	$ 558	$ 454	$ 945	$ 786