Note 9 - Properties - Schedule of Property and Equipment Major Categories (Details) - USD ($) $ in Millions		Mar. 31, 2023		Dec. 31, 2022
Property, Plant and Equipment, Cost		$ 79,841		$ 79,255
Property, Plant and Equipment, Net		56,274		56,038
Property, Plant and Equipment, Accumulated Depreciation		23,567		23,217
Land [Member]
Property, Plant and Equipment, Cost		5,353		5,344
Property, Plant and Equipment, Net		5,353		5,344
Roadrail and Other Track Material [Member]
Property, Plant and Equipment, Cost		18,532		18,419
Property, Plant and Equipment, Net		11,375		11,323
Property, Plant and Equipment, Accumulated Depreciation		$ 7,157		$ 7,096
Property, Plant and Equipment, Useful Life (Year)		42 years		43 years
Road Ties [Member]
Property, Plant and Equipment, Cost		$ 11,764		$ 11,676
Property, Plant and Equipment, Net		8,012		7,977
Property, Plant and Equipment, Accumulated Depreciation		$ 3,752		$ 3,699
Property, Plant and Equipment, Useful Life (Year)		34 years		34 years
Road Ballast [Member]
Property, Plant and Equipment, Cost		$ 6,254		$ 6,222
Property, Plant and Equipment, Net		4,275		4,272
Property, Plant and Equipment, Accumulated Depreciation		$ 1,979		$ 1,950
Property, Plant and Equipment, Useful Life (Year)		34 years		34 years
Road, Other [Member]
Property, Plant and Equipment, Cost	[1]	$ 22,570		$ 22,411
Property, Plant and Equipment, Net		17,501	[1]	17,441
Property, Plant and Equipment, Accumulated Depreciation		$ 5,069	[1]	$ 4,970
Property, Plant and Equipment, Useful Life (Year)		47 years	[1]	47 years
Road [Member]
Property, Plant and Equipment, Cost		$ 59,120		$ 58,728
Property, Plant and Equipment, Net		41,163		41,013
Property, Plant and Equipment, Accumulated Depreciation		17,957		17,715
Equipment, Locomotives [Member]
Property, Plant and Equipment, Cost		9,221		9,166
Property, Plant and Equipment, Net		5,537		5,560
Property, Plant and Equipment, Accumulated Depreciation		$ 3,684		$ 3,606
Property, Plant and Equipment, Useful Life (Year)		18 years		18 years
Equipment, Freight Cars [Member]
Property, Plant and Equipment, Cost		$ 2,621		$ 2,562
Property, Plant and Equipment, Net		1,707		1,664
Property, Plant and Equipment, Accumulated Depreciation		$ 914		$ 898
Property, Plant and Equipment, Useful Life (Year)		23 years		23 years
Equipment, Work Equipment and Other [Member]
Property, Plant and Equipment, Cost		$ 1,278		$ 1,253
Property, Plant and Equipment, Net		788		780
Property, Plant and Equipment, Accumulated Depreciation		$ 490		$ 473
Property, Plant and Equipment, Useful Life (Year)		17 years		17 years
Equipment [Member]
Property, Plant and Equipment, Cost		$ 13,120		$ 12,981
Property, Plant and Equipment, Net		8,032		8,004
Property, Plant and Equipment, Accumulated Depreciation		5,088		4,977
Technology Equipment [Member]
Property, Plant and Equipment, Cost		1,274		1,254
Property, Plant and Equipment, Net		752		729
Property, Plant and Equipment, Accumulated Depreciation		$ 522		$ 525
Property, Plant and Equipment, Useful Life (Year)		12 years		12 years
Construction in Progress [Member]
Property, Plant and Equipment, Cost		$ 974		$ 948
Property, Plant and Equipment, Net		974		948
Property, Plant and Equipment, Accumulated Depreciation		$ 0		$ 0

[1] Other roadway includes grading, bridges and tunnels, signals, buildings, and other road assets.