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, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Computations of the basic and diluted earnings attributable to Ecolab per share amounts
Net income attributable to Ecolab	$ 296.6	$ 258.4	$ 550.1	$ 489.2
Weighted-average common shares outstanding
Basic (in shares)	289.8	292.4	290.2	293.4
Effect of dilutive stock options and units (in shares)	4.3	4.1	4.4	4.1
Diluted (in shares)	294.1	296.5	294.6	297.5
Earnings attributable to Ecolab per common share
Basic (in dollars per share)	$ 1.02	$ 0.88	$ 1.90	$ 1.67
Diluted (in dollars per share)	$ 1.01	$ 0.87	$ 1.87	$ 1.64
Anti-dilutive securities excluded from the computation of EPS	2.0	2.1	3.6	2.1

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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