SPECIAL (GAINS) AND CHARGES - Restructuring and Non-Restructuring Activity (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended	36 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024	Dec. 31, 2024	Jul. 30, 2024
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Global surgical solutions business
Other restructuring information
Professional services	$ 1.6	$ 6.0
Services from professionals, net of tax	1.2	4.5
Special (gains) and charges
Other restructuring information
Business combination advisory and legal fees, pre tax	1.5	2.5
Business combination and integration related costs, after tax	1.1	1.9
Other special gains and charges	(13.0)	1.6
Specific legal reserve and related legal charges
Other restructuring information
Other special gains and charges	13.0	1.6
Other special gains and charges, after-tax	11.3	0.9
Prior Year Plans
Other restructuring information
Restructuring liability	5.6		$ 6.5	$ 6.5
Combined Program
Other restructuring information
Restructuring charges incurred, pre-tax	184.1
Restructuring charges incurred, after tax	151.5
Restructuring liability	5.7		12.8	12.8
Cash payments	7.1
Restructuring
Recorded expense (income) and accrual				170.1
Net cash payments				(156.0)
Non-cash net charges				(15.3)
Reclassification				14.0
Combined Program | Special (gains) and charges
Other restructuring information
Restructuring charges incurred, pre-tax		18.1
Combined Program | Cost of sales
Other restructuring information
Restructuring charges incurred, pre-tax		$ 1.6
Combined Program | Employee termination costs
Other restructuring information
Restructuring liability			12.8	12.8
Restructuring
Recorded expense (income) and accrual				118.0
Net cash payments				(124.5)
Reclassification				19.3
Combined Program | Asset disposals
Restructuring
Recorded expense (income) and accrual				15.3
Non-cash net charges				(15.3)
Combined Program | Other
Restructuring
Recorded expense (income) and accrual				36.8
Net cash payments				(31.5)
Reclassification				(5.3)
One Ecolab
Other restructuring information
Restructuring charge expected to be incurred, pre-tax					$ 175.0
Restructuring charge expected to be incurred, after tax					136.0
Restructuring and related special charges, pre-tax					50.0
Restructuring and related activities special charges, after tax					$ 39.0
Restructuring charges incurred to date, pre-tax	121.2
Restructuring charges incurred to date, after-tax	93.5
Special charges to date	28.5
Special charges to date, after tax	21.5
Restructuring liability	84.7		54.9	54.9
Restructuring
Recorded expense (income) and accrual	39.4		76.5
Net cash payments	(9.6)		(26.9)
Reclassification			5.3
One Ecolab | Special (gains) and charges
Other restructuring information
Restructuring charges incurred, pre-tax	39.4
Professional services	4.8
Services from professionals, net of tax	3.6
One Ecolab | Cost of sales
Other restructuring information
Restructuring charges incurred, pre-tax	4.8
One Ecolab | Employee termination costs
Other restructuring information
Restructuring charges incurred, pre-tax	39.4
Restructuring charges incurred, after tax	30.5
Restructuring liability	74.9		46.3	46.3
Restructuring
Recorded expense (income) and accrual	33.1		46.3
Net cash payments	(4.5)
One Ecolab | Other
Other restructuring information
Restructuring liability	9.8		8.6	$ 8.6
Restructuring
Recorded expense (income) and accrual	6.3		30.2
Net cash payments	$ (5.1)		(26.9)
Reclassification			$ 5.3