SIGNIFICANT ACCOUNTING POLICIES (Details 6) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	12 Months Ended
Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Asset Retirement Obligations
Asset retirement obligation liability	$ 9.5us-gaap_AssetRetirementObligation				$ 10.5us-gaap_AssetRetirementObligation				$ 9.5us-gaap_AssetRetirementObligation	$ 10.5us-gaap_AssetRetirementObligation
Computations of the basic and diluted earnings attributable to Ecolab per share amounts
Net income attributable to Ecolab	$ 335.5	$ 364.9	$ 311.4	$ 191.0	$ 287.1	$ 308.0	$ 213.1	$ 159.6	$ 1,202.8	$ 967.8	$ 703.6
Weighted-average common shares outstanding
Basic (in shares)	300.1	300.0	299.6	300.6	301.2	301.2	301.5	295.4	300.1	299.9	292.5
Effect of dilutive stock options, units and awards (in shares)									5.8	6.0	6.4
Diluted (in shares)	305.6	305.7	305.2	306.5	307.5	307.2	307.4	300.9	305.9	305.9	298.9
Earnings attributable to Ecolab per common share
Basic (in dollars per share)	$ 1.12us-gaap_EarningsPerShareBasic	$ 1.22us-gaap_EarningsPerShareBasic	$ 1.04us-gaap_EarningsPerShareBasic	$ 0.64us-gaap_EarningsPerShareBasic	$ 0.95us-gaap_EarningsPerShareBasic	$ 1.02us-gaap_EarningsPerShareBasic	$ 0.71us-gaap_EarningsPerShareBasic	$ 0.54us-gaap_EarningsPerShareBasic	$ 4.01us-gaap_EarningsPerShareBasic	$ 3.23us-gaap_EarningsPerShareBasic	$ 2.41us-gaap_EarningsPerShareBasic
Diluted (in dollars per share)	$ 1.10us-gaap_EarningsPerShareDiluted	$ 1.19us-gaap_EarningsPerShareDiluted	$ 1.02us-gaap_EarningsPerShareDiluted	$ 0.62us-gaap_EarningsPerShareDiluted	$ 0.93us-gaap_EarningsPerShareDiluted	$ 1.00us-gaap_EarningsPerShareDiluted	$ 0.69us-gaap_EarningsPerShareDiluted	$ 0.53us-gaap_EarningsPerShareDiluted	$ 3.93us-gaap_EarningsPerShareDiluted	$ 3.16us-gaap_EarningsPerShareDiluted	$ 2.35us-gaap_EarningsPerShareDiluted
Anti-dilutive securities excluded from the computation of earnings per share (in shares)									3.4	1.8	2.6

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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