Document and Entity Information Document - shares	9 Months Ended
	Sep. 30, 2018	Oct. 19, 2018
Entity Information
Entity Registrant Name	Tennant Company
Entity Central Index Key	0000097134
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		18,125,000
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q3
Amendment Flag	false