Properties - Schedule of Net Properties (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 44,324	$ 43,227
Accumulated Depreciation	(12,560)	(12,077)
Properties - Net	31,764	31,150
Total Road
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	30,091	28,824
Accumulated Depreciation	(7,790)	(7,324)
Properties - Net	22,301	21,500
Rail and Other Track Material
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	7,694	7,326
Accumulated Depreciation	(1,606)	(1,493)
Properties - Net	$ 6,088	$ 5,833
Annual Depreciation Rate	2.50%	2.50%
Estimated useful life	40 years	40 years
Ties
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 5,665	$ 5,368
Accumulated Depreciation	(1,446)	(1,292)
Properties - Net	$ 4,219	$ 4,076
Annual Depreciation Rate	3.70%	3.70%
Estimated useful life	27 years	27 years
Grading
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 2,662	$ 2,600
Accumulated Depreciation	(542)	(514)
Properties - Net	$ 2,120	$ 2,086
Annual Depreciation Rate	1.40%	1.40%
Estimated useful life	90 years	90 years
Ballast
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 2,994	$ 2,897
Accumulated Depreciation	(921)	(860)
Properties - Net	$ 2,073	$ 2,037
Annual Depreciation Rate	2.70%	2.70%
Estimated useful life	37 years	37 years
Bridges, Trestles, and Culverts
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 2,405	$ 2,306
Accumulated Depreciation	(356)	(317)
Properties - Net	$ 2,049	$ 1,989
Annual Depreciation Rate	1.60%	1.60%
Estimated useful life	70 years	70 years
Signals and Interlockers
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 2,759	$ 2,523
Accumulated Depreciation	(588)	(496)
Properties - Net	$ 2,171	$ 2,027
Annual Depreciation Rate	4.00%	4.00%
Estimated useful life	25 years	25 years
Buildings
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 1,278	$ 1,238
Accumulated Depreciation	(464)	(447)
Properties - Net	$ 814	$ 791
Annual Depreciation Rate	2.50%	2.50%
Estimated useful life	40 years	40 years
Other
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 4,634	$ 4,566
Accumulated Depreciation	(1,867)	(1,905)
Properties - Net	$ 2,767	$ 2,661
Annual Depreciation Rate	4.20%	4.20%
Estimated useful life	24 years	24 years
Total Equipment
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 11,606	$ 11,604
Accumulated Depreciation	(4,770)	(4,740)
Properties - Net	6,836	6,864
Locomotive
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	6,083	6,110
Accumulated Depreciation	(2,490)	(2,504)
Properties - Net	$ 3,593	$ 3,606
Annual Depreciation Rate	3.50%	3.50%
Estimated useful life	29 years	29 years
Freight Cars
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 3,262	$ 3,386
Accumulated Depreciation	(998)	(1,046)
Properties - Net	$ 2,264	$ 2,340
Annual Depreciation Rate	2.90%	2.90%
Estimated useful life	35 years	35 years
Work Equipment and Other
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 2,261	$ 2,108
Accumulated Depreciation	(1,282)	(1,190)
Properties - Net	$ 979	$ 918
Annual Depreciation Rate	7.40%	7.40%
Estimated useful life	14 years	14 years
Land
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 1,849	$ 1,833
Properties - Net	1,849	1,833
Construction In Progress
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	778	913
Properties - Net	$ 778	913
Other
Property, Plant and Equipment, Net, by Type [Abstract]
Cost		53
Accumulated Depreciation		(13)
Properties - Net		$ 40
Estimated useful life		32 years