SEGMENT INFORMATION - Segment Financial Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Segment Reporting Information [Line Items]
Total sales	$ 2,497	$ 2,194
Income (loss) from operations	412	276
Interest expense and other, net	(49)	(43)
Income before income taxes	363	233
Freight Segment
Segment Reporting Information [Line Items]
Total sales	1,824	1,556
Transit Segment
Segment Reporting Information [Line Items]
Total sales	673	638
Corporate Activities and Elimination
Segment Reporting Information [Line Items]
Total sales	(24)	(25)
Income (loss) from operations	(30)	(20)
Interest expense and other, net	(49)	(43)
Income before income taxes	(79)	(63)
Corporate Activities and Elimination | Freight Segment
Segment Reporting Information [Line Items]
Total sales	13	14
Corporate Activities and Elimination | Transit Segment
Segment Reporting Information [Line Items]
Total sales	11	11
Operating Segments | Freight Segment
Segment Reporting Information [Line Items]
Total sales	1,837	1,570
Income (loss) from operations	368	226
Interest expense and other, net	0	0
Income before income taxes	368	226
Operating Segments | Transit Segment
Segment Reporting Information [Line Items]
Total sales	684	649
Income (loss) from operations	74	70
Interest expense and other, net	0	0
Income before income taxes	$ 74	$ 70