Note 2 - Operations and Segmentation - Summary of Freight and Other Revenues (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Revenue from Contract with Customer, Excluding Assessed Tax	$ 6,056	$ 5,860
Bulk [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	1,897	1,832
Industrial [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	2,017	1,921
Premium [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	1,742	1,687
Cargo and Freight [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	5,656	5,440
Other Subsidiary Revenues [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	235	205
Accessorial Revenues [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	151	201
Other Miscellaneous Product and Service Revenues [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 14	$ 14