Note 9 - Warranty (Details Textual)	3 Months Ended
Mar. 31, 2021
Minimum [Member]
Machine Warranty, Period (Year)	1 year
Machine Warranty, General Period Following Sale that Majority of Claims are Paid (Month)	6 months
Maximum [Member]
Machine Warranty, Period (Year)	4 years
Machine Warranty, General Period Following Sale that Majority of Claims are Paid (Month)	9 months

The general period of time following a sale that the majority of claims are paid under machine warranty.

No definition available.

Name:	tnc_MachineWarrantyGeneralPeriodFollowingSaleThatMajorityOfClaimsArePaid
Namespace Prefix:	tnc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration