Earnings Attributable to Ecolab Per Common Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Computations of the basic and diluted earnings attributable to Ecolab per share amounts
Net income attributable to Ecolab	$ 213.1	$ 184.5	$ 372.7	$ 234.2
Weighted-average common shares outstanding
Basic (in shares)	301.5	291.9	298.5	291.7
Effect of dilutive stock options, units and awards (in shares)	5.9	6.3	5.7	6.4
Diluted (in shares)	307.4	298.2	304.2	298.1
Earnings attributable to Ecolab per common share
Basic (in dollars per share)	$ 0.71	$ 0.63	$ 1.25	$ 0.80
Diluted (in dollars per share)	$ 0.69	$ 0.62	$ 1.23	$ 0.79
Anti-dilutive securities excluded from computation of earnings per share (in shares)	0.3	0.8	2.3	3.1

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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