EARNINGS ATTRIBUTABLE TO ECOLAB PER COMMON SHARE ("EPS") (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Computations of the basic and diluted earnings attributable to Ecolab per share amounts
Net income from continuing operations attributable to Ecolab	$ 128.9	$ 343.4	$ 420.9	$ 595.0
Net (loss) income from discontinued operations, net of tax (Note 4) (c)	(2,163.9)	25.2	(2,172.5)	70.1
Net (loss) income attributable to Ecolab	$ (2,035.0)	$ 368.6	$ (1,751.6)	$ 665.1
Weighted-average common shares outstanding
Basic (in shares)	288.2	287.6	288.5	287.9
Effect of dilutive stock options and units (in shares)	3.3	4.4	3.5	4.3
Diluted (in shares)	291.5	292.1	292.0	292.2
Basic
Continuing operations	$ 0.45	$ 1.19	$ 1.46	$ 2.07
Discontinued operations	(7.51)	0.09	(7.53)	0.24
Earnings (loss) attributable to Ecolab	(7.06)	1.28	(6.07)	2.31
Diluted
Continuing operations	0.44	1.18	1.44	2.04
Discontinued operations	(7.42)	0.08	(7.44)	0.24
Earnings (loss) attributable to Ecolab	$ (6.98)	$ 1.26	$ (6.00)	$ 2.28
Anti-dilutive securities excluded from the computation of EPS	1.0	0.3	1.0	1.5