Document and Entity Information	9 Months Ended
	Sep. 30, 2018 shares
Document and Entity Information
Entity Registrant Name	ECOLAB INC.
Entity Central Index Key	0000031462
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	288,873,052
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q3