GOODWILL AND INTANGIBLE ASSETS - Summary of Change in the Carrying Amount of Goodwill by Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Goodwill [Roll Forward]
Balance beginning of period	$ 8,587	$ 8,485
Additions	35	229
Foreign currency impact	(114)	(127)
Balance end of period	8,508	8,587
Freight Segment
Goodwill [Roll Forward]
Balance beginning of period	7,073	6,872
Additions	35	214
Foreign currency impact	(23)	(13)
Balance end of period	7,085	7,073
Transit Segment
Goodwill [Roll Forward]
Balance beginning of period	1,514	1,613
Additions	0	15
Foreign currency impact	(91)	(114)
Balance end of period	$ 1,423	$ 1,514