Note 6 - Other Income - Schedule of Other Income (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Gain on non-operating asset dispositions [a]	[1]	$ 98	$ 63	$ 114	$ 72
Rental income		39	34	75	67
Net periodic pension costs		21	6	41	11
Environmental remediation and restoration		(5)	(5)	(31)	(9)
Other		10	27	11	35
Total		$ 163	$ 125	$ 210	$ 176

[1] 2022 includes a $79 million gain from a land sale to the Illinois State Toll Highway Authority. 2021 includes a $50 million gain from a sale to the Colorado Department of Transportation.