SEGMENT INFORMATION - Summary of Reconciliation Operating Income to EBITDA (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Net revenues	$ 2,254	$ 1,990	$ 4,236	$ 3,709
Segment cost of revenues	1,551	1,375	2,913	2,552
Depreciation	21	22	42	42
Segment earnings	175	143	278	227
Reconciliation of profit/(loss):
Corporate/other profit/(loss)	(33)	(31)	(67)	(66)
Interest expense, net	(36)	(37)	(66)	(75)
Depreciation	(21)	(22)	(42)	(42)
Amortization	(68)	(59)	(131)	(119)
Contingent consideration and compensation	1	0	1	(1)
Non-service pension cost	(5)	(5)	(10)	(9)
Systems and business enablement	(25)	(18)	(52)	(30)
Business process transformation expenses	0	0	0	(4)
Acquisition and divestiture related expenses	(9)	(11)	(28)	(14)
Restructuring program related costs	0	(11)	0	(14)
Other	(10)	(1)	(9)	(3)
Income before income taxes	138	108	209	154
Operating Segments, Excluding Intersegment Elimination
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Net revenues	2,254	1,990	4,236	3,709
Intersegment Eliminations
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Net revenues	(1)	(1)	(3)	(2)
Operating Segments
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Net revenues	2,255	1,991	4,239	3,711
Segment earnings	344	303	613	531
Safety Services | Operating Segments, Excluding Intersegment Elimination
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Net revenues	1,481	1,361	2,896	2,628
Safety Services | Intersegment Eliminations
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Net revenues	(1)	(1)	(1)	(1)
Safety Services | Operating Segments
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Net revenues	1,482	1,362	2,897	2,629
Segment cost of revenues	927	856	1,815	1,654
Segment operating expenses	314	285	620	563
Segment other income/expense	2	1	2	1
Depreciation	9	10	18	18
Segment earnings	252	232	482	431
Reconciliation of profit/(loss):
Depreciation	(9)	(10)	(18)	(18)
Specialty Services | Operating Segments, Excluding Intersegment Elimination
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Net revenues	773	629	1,340	1,081
Specialty Services | Intersegment Eliminations
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Net revenues	0	0	(2)	(1)
Specialty Services | Operating Segments
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Net revenues	773	629	1,342	1,082
Segment cost of revenues	624	516	1,100	893
Segment operating expenses	71	58	138	120
Segment other income/expense	4	5	7	9
Depreciation	10	11	20	22
Segment earnings	92	71	131	100
Reconciliation of profit/(loss):
Depreciation	$ (10)	$ (11)	$ (20)	$ (22)