GOODWILL AND INTANGIBLE ASSETS - Schedule of Change in the Carrying Amount of Goodwill by Segment (Details) $ in Millions	3 Months Ended
	Mar. 31, 2026 USD ($)
Goodwill [Roll Forward]
Beginning balance	$ 10,216
Additions/adjustments	481
Foreign currency impact	(72)
Ending balance	10,625
Freight Segment
Goodwill [Roll Forward]
Beginning balance	8,567
Additions/adjustments	6
Foreign currency impact	(12)
Ending balance	8,561
Transit Segment
Goodwill [Roll Forward]
Beginning balance	1,649
Additions/adjustments	475
Foreign currency impact	(60)
Ending balance	$ 2,064