EARNINGS ATTRIBUTABLE TO ECOLAB PER COMMON SHARE (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Computations of the basic and diluted earnings attributable to Ecolab per share amounts
Net income attributable to Ecolab	$ 258.4	$ 302.0	$ 489.2	$ 535.4
Weighted-average common shares outstanding
Basic (in shares)	292.4	296.2	293.4	297.2
Effect of dilutive stock options and units (in shares)	4.1	4.9	4.1	5.0
Diluted (in shares)	296.5	301.1	297.5	302.2
Earnings attributable to Ecolab per common share
Basic (in dollars per share)	$ 0.88	$ 1.02	$ 1.67	$ 1.80
Diluted (in dollars per share)	$ 0.87	$ 1.00	$ 1.64	$ 1.77
Anti-dilutive stock options, units and awards excluded from computation of earnings per share (in shares)	2.1	1.9	2.1	1.9