XML 18 R1.htm IDEA: XBRL DOCUMENT v3.20.4
Document And Entity Information - USD ($)
 12 Months Ended
Dec. 31, 2020
Jan. 29, 2021
Jun. 30, 2020
Document Information [Line Items]      
Entity Central Index Key 0000097134    
Entity Registrant Name TENNANT CO    
Amendment Flag false    
Current Fiscal Year End Date --12-31    
Document Fiscal Period Focus FY    
Document Fiscal Year Focus 2020    
Document Type 10-K    
Document Annual Report true    
Document Period End Date Dec. 31, 2020    
Document Transition Report false    
Entity File Number 001-16191    
Entity Incorporation, State or Country Code MN    
Entity Tax Identification Number 41-0572550    
Entity Address, Address Line One 10400 Clean Street    
Entity Address, City or Town Eden Prairie    
Entity Address, State or Province MN    
Entity Address, Postal Zip Code 55344    
City Area Code 763    
Local Phone Number 540-1200    
Title of 12(b) Security Common Stock, par value $0.375 per share    
Trading Symbol TNC    
Security Exchange Name NYSE    
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Large Accelerated Filer    
Entity Small Business false    
Entity Emerging Growth Company false    
Entity Shell Company false    
Entity Public Float     $ 1,107,917,527
Entity Common Stock, Shares Outstanding   18,516,296