Note 11 - Properties - Schedule of Property and Equipment Major Categories (Details) - USD ($) $ in Millions		6 Months Ended		12 Months Ended
		Jun. 30, 2022		Dec. 31, 2021
Property, Plant and Equipment, Cost		$ 78,073		$ 77,275
Property, Plant and Equipment, Net		55,315		54,871
Property, Plant and Equipment, Accumulated Depreciation		22,758		22,404
Land [Member]
Property, Plant and Equipment, Cost		5,333		5,339
Property, Plant and Equipment, Net		5,333		5,339
Roadrail and Other Track Material [Member]
Property, Plant and Equipment, Cost		18,217		17,980
Property, Plant and Equipment, Net		11,240		11,136
Property, Plant and Equipment, Accumulated Depreciation		$ 6,977		$ 6,844
Property, Plant and Equipment, Useful Life (Year)		43 years		44 years
Road Ties [Member]
Property, Plant and Equipment, Cost		$ 11,538		$ 11,364
Property, Plant and Equipment, Net		7,933		7,848
Property, Plant and Equipment, Accumulated Depreciation		$ 3,605		$ 3,516
Property, Plant and Equipment, Useful Life (Year)		34 years		34 years
Road Ballast [Member]
Property, Plant and Equipment, Cost		$ 6,140		$ 6,070
Property, Plant and Equipment, Net		4,237		4,218
Property, Plant and Equipment, Accumulated Depreciation		$ 1,903		$ 1,852
Property, Plant and Equipment, Useful Life (Year)		34 years		34 years
Road, Other [Member]
Property, Plant and Equipment, Cost	[1]	$ 21,945		$ 21,593
Property, Plant and Equipment, Net		17,134	[1]	16,936
Property, Plant and Equipment, Accumulated Depreciation		$ 4,811	[1]	$ 4,657
Property, Plant and Equipment, Useful Life (Year)		47 years	[1]	47 years
Road [Member]
Property, Plant and Equipment, Cost		$ 57,840		$ 57,007
Property, Plant and Equipment, Net		40,544		40,138
Property, Plant and Equipment, Accumulated Depreciation		17,296		16,869
Equipment, Locomotives [Member]
Property, Plant and Equipment, Cost		9,158		9,371
Property, Plant and Equipment, Net		5,541		5,592
Property, Plant and Equipment, Accumulated Depreciation		$ 3,617		$ 3,779
Property, Plant and Equipment, Useful Life (Year)		18 years		17 years
Equipment, Freight Cars [Member]
Property, Plant and Equipment, Cost		$ 2,407		$ 2,227
Property, Plant and Equipment, Net		1,545		1,405
Property, Plant and Equipment, Accumulated Depreciation		$ 862		$ 822
Property, Plant and Equipment, Useful Life (Year)		23 years		24 years
Equipment, Work Equipment and Other [Member]
Property, Plant and Equipment, Cost		$ 1,191		$ 1,161
Property, Plant and Equipment, Net		747		750
Property, Plant and Equipment, Accumulated Depreciation		$ 444		$ 411
Property, Plant and Equipment, Useful Life (Year)		18 years		18 years
Equipment [Member]
Property, Plant and Equipment, Cost		$ 12,756		$ 12,759
Property, Plant and Equipment, Net		7,833		7,747
Property, Plant and Equipment, Accumulated Depreciation		4,923		5,012
Technology Equipment [Member]
Property, Plant and Equipment, Cost		1,268		1,209
Property, Plant and Equipment, Net		729		686
Property, Plant and Equipment, Accumulated Depreciation		$ 539		$ 523
Property, Plant and Equipment, Useful Life (Year)		13 years		12 years
Construction in Progress [Member]
Property, Plant and Equipment, Cost		$ 876		$ 961
Property, Plant and Equipment, Net		876		961
Property, Plant and Equipment, Accumulated Depreciation		$ 0		$ 0

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