SIGNIFICANT ACCOUNTING POLICIES (Details 6) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Asset Retirement Obligations
Asset retirement obligation liability	$ 10.2				$ 9.5				$ 10.2	$ 9.5
Computations of the basic and diluted earnings attributable to Ecolab per share amounts
Net income attributable to Ecolab	$ 208.9	$ 257.8	$ 302.0	$ 233.4	$ 335.5	$ 364.9	$ 311.4	$ 191.0	$ 1,002.1	$ 1,202.8	$ 967.8
Weighted-average common shares outstanding
Basic (in shares)	295.8	295.2	296.2	298.2	300.1	300.0	299.6	300.6	296.4	300.1	299.9
Effect of dilutive stock options, units and awards (in shares)									5.0	5.8	6.0
Diluted (in shares)	300.6	300.0	301.1	303.2	305.6	305.7	305.2	306.5	301.4	305.9	305.9
Earnings attributable to Ecolab per common share
Basic (in dollars per share)	$ 0.71	$ 0.87	$ 1.02	$ 0.78	$ 1.12	$ 1.22	$ 1.04	$ 0.64	$ 3.38	$ 4.01	$ 3.23
Diluted (in dollars per share)	$ 0.69	$ 0.86	$ 1.00	$ 0.77	$ 1.10	$ 1.19	$ 1.02	$ 0.62	$ 3.32	$ 3.93	$ 3.16
Anti-dilutive stock options, units and awards excluded from computation of earnings per share (in shares)									3.5	3.4	1.8