Properties - Schedule of Net Properties (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 53,816	$ 52,191
Accumulated Depreciation	(17,005)	(16,533)
Properties - Net (Note 6)	36,811	35,658
Total Road
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	39,268	37,684
Accumulated Depreciation	(11,968)	(11,648)
Properties - Net (Note 6)	27,300	26,036
Rail and Other Track Material
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	10,318	9,883
Accumulated Depreciation	(2,311)	(2,199)
Properties - Net (Note 6)	$ 8,007	$ 7,684
Annual Depreciation Rate	2.50%	2.50%
Estimated Useful Life (Avg. Years)	41 years	41 years
Ties
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 7,488	$ 7,269
Accumulated Depreciation	(2,374)	(2,252)
Properties - Net (Note 6)	$ 5,114	$ 5,017
Annual Depreciation Rate	3.50%	3.50%
Estimated Useful Life (Avg. Years)	28 years	28 years
Grading
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 3,240	$ 2,813
Accumulated Depreciation	(726)	(699)
Properties - Net (Note 6)	$ 2,514	$ 2,114
Annual Depreciation Rate	1.30%	1.30%
Estimated Useful Life (Avg. Years)	75 years	75 years
Ballast
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 3,581	$ 3,494
Accumulated Depreciation	(1,183)	(1,159)
Properties - Net (Note 6)	$ 2,398	$ 2,335
Annual Depreciation Rate	2.60%	2.60%
Estimated Useful Life (Avg. Years)	38 years	38 years
Bridges, Trestles, and Culverts
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 3,391	$ 3,234
Accumulated Depreciation	(591)	(572)
Properties - Net (Note 6)	$ 2,800	$ 2,662
Annual Depreciation Rate	1.70%	1.70%
Estimated Useful Life (Avg. Years)	60 years	60 years
Signals and Interlockers
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 3,476	$ 3,476
Accumulated Depreciation	(1,464)	(1,480)
Properties - Net (Note 6)	$ 2,012	$ 1,996
Annual Depreciation Rate	4.10%	4.10%
Estimated Useful Life (Avg. Years)	24 years	24 years
Buildings
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 1,577	$ 1,498
Accumulated Depreciation	(580)	(568)
Properties - Net (Note 6)	$ 997	$ 930
Annual Depreciation Rate	2.50%	2.50%
Estimated Useful Life (Avg. Years)	40 years	40 years
Other
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 6,197	$ 6,017
Accumulated Depreciation	(2,739)	(2,719)
Properties - Net (Note 6)	$ 3,458	$ 3,298
Annual Depreciation Rate	4.10%	4.10%
Estimated Useful Life (Avg. Years)	25 years	25 years
Total Equipment
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 11,264	$ 11,162
Accumulated Depreciation	(5,037)	(4,885)
Properties - Net (Note 6)	6,227	6,277
Locomotive
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	5,374	5,252
Accumulated Depreciation	(2,267)	(2,175)
Properties - Net (Note 6)	$ 3,107	$ 3,077
Annual Depreciation Rate	3.80%	3.80%
Estimated Useful Life (Avg. Years)	26 years	26 years
Freight Cars
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 2,246	$ 2,311
Accumulated Depreciation	(358)	(407)
Properties - Net (Note 6)	$ 1,888	$ 1,904
Annual Depreciation Rate	3.10%	3.10%
Estimated Useful Life (Avg. Years)	32 years	32 years
Work Equipment and Other
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 3,644	$ 3,599
Accumulated Depreciation	(2,412)	(2,303)
Properties - Net (Note 6)	$ 1,232	$ 1,296
Annual Depreciation Rate	8.90%	8.90%
Estimated Useful Life (Avg. Years)	11 years	11 years
Land
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 2,286	$ 2,276
Properties - Net (Note 6)	2,286	2,276
Construction In Progress
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	998	1,069
Properties - Net (Note 6)	$ 998	$ 1,069