Properties - Schedule of Net Properties (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 48,105	$ 46,505
Accumulated depreciation	(13,863)	(13,490)
Net book value	34,242	33,015
Total Road
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	34,792	34,076
Accumulated depreciation	(9,727)	(9,694)
Net book value	25,065	24,382
Rail and Other Track Material
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	8,660	8,761
Accumulated depreciation	(1,405)	(1,835)
Net book value	$ 7,255	$ 6,926
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	$ 6,763	$ 6,522
Accumulated depreciation	(2,010)	(1,923)
Net book value	$ 4,753	$ 4,599
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	$ 2,741	$ 2,751
Accumulated depreciation	(637)	(624)
Net book value	$ 2,104	$ 2,127
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	$ 3,383	$ 3,289
Accumulated depreciation	(1,130)	(1,094)
Net book value	$ 2,253	$ 2,195
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	$ 2,989	$ 2,794
Accumulated depreciation	(454)	(411)
Net book value	$ 2,535	$ 2,383
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	$ 3,299	$ 3,266
Accumulated depreciation	(1,210)	(1,086)
Net book value	$ 2,089	$ 2,180
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	$ 1,416	$ 1,388
Accumulated depreciation	(558)	(514)
Net book value	$ 858	$ 874
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	$ 5,541	$ 5,305
Accumulated depreciation	(2,323)	(2,207)
Net book value	$ 3,218	$ 3,098
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	$ 10,296	$ 10,125
Accumulated depreciation	(4,136)	(3,796)
Net book value	6,160	6,329
Locomotive
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	4,848	4,912
Accumulated depreciation	(1,856)	(1,732)
Net book value	$ 2,992	$ 3,180
Annual depreciation rate	3.80%	3.60%
Estimated useful life (avg. years)	26 years	27 years
Freight Cars
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 2,316	$ 2,322
Accumulated depreciation	(369)	(358)
Net book value	$ 1,947	$ 1,964
Annual depreciation rate	3.10%	2.90%
Estimated useful life (avg. years)	32 years	35 years
Work Equipment and Other
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 3,132	$ 2,891
Accumulated depreciation	(1,911)	(1,706)
Net book value	$ 1,221	$ 1,185
Annual depreciation rate	8.90%	8.20%
Estimated useful life (avg. years)	11 years	12 years
Land
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 2,272	$ 1,885
Net book value	2,272	1,885
Construction In Progress
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	745	419
Net book value	$ 745	$ 419