SEGMENT REPORTING - Summary of Segment Revenue and Net Before Tax Information by Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Revenue	$ 12,636	$ 11,783	$ 12,011
Used vehicle sales, net	(72)	(196)	(450)
Segment EBT	839	922	1,264
Intangible amortization expense	(53)	(35)	(37)
Other items impacting comparability, net	(13)	(157)	83
Earnings from continuing operations before income taxes	661	618	1,216
UNITED KINGDOM
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Business exit costs		2	49
SCS
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Revenue	5,300	4,875	4,720
Operating Segments | FMS
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Revenue	5,888	5,930	6,327
Direct operating costs	4,638	4,651	4,845
Used vehicle sales, net	(72)	(194)	(401)
Other segment items	806	808	826
Segment EBT	516	665	1,057
Operating Segments | SCS
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Revenue	5,300	4,875	4,720
Direct operating costs	4,735	4,420	4,253
Used vehicle sales, net	0	0	0
Other segment items	233	224	249
Segment EBT	332	231	218
Operating Segments | DTS
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Revenue	2,446	1,785	1,786
Direct operating costs	2,270	1,634	1,670
Used vehicle sales, net	0	0	0
Other segment items	51	30	13
Segment EBT	125	121	103
Eliminations
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Revenue	(998)	(807)	(822)
Segment EBT	(134)	(95)	(114)
Segment Reconciling Items
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Unallocated Central Support Services	(71)	(72)	(83)
Intangible amortization expense	(53)	(35)	(37)
Non-operating pension costs, net	(41)	(40)	(11)
Other items impacting comparability, net	$ (13)	$ (157)	$ 83