SPECIAL (GAINS) AND CHARGES - Restructuring and Non-Restructuring Activity (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended		24 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Jul. 30, 2024	Mar. 31, 2023	Feb. 28, 2023
Other restructuring information
Special (gains) and charges	$ (332.6)		$ 36.7	$ (292.2)	$ 82.2
Non-restructuring Special (Gains) and Charges
Accounts payable	1,812.3			1,812.3		$ 1,566.3
Other current liabilities	1,413.8			1,413.8		1,334.9
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Global surgical solutions business
Other restructuring information
Professional services	3.3		4.8	14.6	4.8
Services from professionals, net of tax.	2.5		3.6	11.3	3.6
Disposal group, held-for-sale, not discontinued operations | Global surgical solutions business
Other restructuring information
Special gain (loss) on sale of business before tax	365.3			365.3
Special gain (loss) on sale of business after tax	264.2			264.2
Special (gains) and charges
Other restructuring information
Business combination advisory and legal fees, pre tax	3.5		3.0	8.3	11.5
Business combination advisory and legal fees, after tax				6.3	8.6
Special (gains) and charges	(332.6)		36.7	(292.2)	82.2
Other special gains and charges	3.1		8.9	(8.8)	19.6
Non-restructuring Special (Gains) and Charges
Business combination and integration related costs, pre tax			3.0
Business combination and integration related costs, after tax	2.7		2.2
Cost of sales
Other restructuring information
Special (gains) and charges	0.9		5.9	3.2	17.2
Specific legal reserve and related legal charges
Other restructuring information
Other special gains and charges	3.1		8.9	8.8	19.6
Other special gains and charges, after-tax	2.3		6.7	6.9	14.9
Other Restructuring Plan
Other restructuring information
Restructuring charge expected to be incurred, pre-tax	5.3			5.3
Restructuring charge expected to be incurred, after tax	4.0			4.0
Restructuring charges incurred, pre-tax		$ 10.6
Restructuring charges incurred, after tax		$ 8.0
Prior Year Plans
Other restructuring information
Restructuring liability	6.8			6.8
Combined Program
Restructuring
Recorded expense (income) and accrual	23.3					144.9
Net cash payments	(41.9)					(107.1)
Non-cash charges	(1.2)					(14.0)
Reclassification	(5.3)					19.3
Other restructuring information
Restructuring charge expected to be incurred, pre-tax								$ 19.3	$ 195.0
Restructuring charge expected to be incurred, after tax								$ 14.5	$ 150.0
Restructuring liability	18.0			18.0		43.1
Restructuring charges incurred, pre-tax	182.2
Restructuring charges incurred, after tax	150.7
Combined Program | Special (gains) and charges
Other restructuring information
Restructuring charges incurred, pre-tax	0.4		20.0	20.1	46.3
Combined Program | Cost of sales
Other restructuring information
Restructuring charges incurred, pre-tax	0.9		5.9	3.2	17.2
Combined Program | Employee termination costs
Restructuring
Recorded expense (income) and accrual	3.8					114.2
Net cash payments	(29.5)					(90.4)
Reclassification						19.3
Other restructuring information
Restructuring liability	17.4			17.4		43.1
Restructuring charges incurred, pre-tax	1.3		24.2	23.3	57.3
Restructuring charges incurred, after tax	0.6		$ 20.5	17.8	$ 46.9
Combined Program | Asset disposals
Restructuring
Recorded expense (income) and accrual	1.2					14.0
Non-cash charges	(1.2)					(14.0)
Combined Program | Other.
Restructuring
Recorded expense (income) and accrual	18.3					16.7
Net cash payments	(12.4)					$ (16.7)
Reclassification	(5.3)
Other restructuring information
Restructuring liability	0.6			0.6
One Ecolab Initiative Program [Member]
Restructuring
Recorded expense (income) and accrual				22.7
Net cash payments				(13.9)
Reclassification				5.3
Other restructuring information
Restructuring charge expected to be incurred, pre-tax	5.3			5.3			$ 175.0
Restructuring charge expected to be incurred, after tax	4.0			4.0			136.0
Restructuring liability	14.1			14.1
Special charges to date	16.2			16.2
Special charges to date, after tax	12.2			12.2
Restructuring charges incurred to date, pre-tax	28.0			28.0
Restructuring charges incurred to date, after-tax	21.3			21.3
One Ecolab Initiative Program [Member] | Special (gains) and charges
Other restructuring information
Restructuring charge expected to be incurred, pre-tax							50.0
Restructuring charge expected to be incurred, after tax							$ 39.0
Restructuring charges incurred, pre-tax	24.4			38.9
Professional services	7.0			16.2
Services from professionals, net of tax.	5.2			12.2
One Ecolab Initiative Program [Member] | Employee termination costs
Restructuring
Recorded expense (income) and accrual				2.8
Other restructuring information
Restructuring liability	2.8			2.8
Restructuring charges incurred, pre-tax	17.4			22.7
Restructuring charges incurred, after tax	13.3			17.3
One Ecolab Initiative Program [Member] | Other.
Restructuring
Recorded expense (income) and accrual				19.9
Net cash payments				(13.9)
Reclassification				5.3
Other restructuring information
Restructuring liability	$ 11.3			$ 11.3