Revenue from Contracts with Customers (Details 2) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Contract with Customer, Contract Liability [Roll Forward] [Roll Forward]
Beginning balance	$ 16.7	$ 13.5
Additions to sales incentive accrual	24.7	30.5
Contract payments	(27.7)	(27.0)
Foreign currency fluctuations	0.0	(0.3)
Ending balance	$ 13.7	$ 16.7

Contract with Customer, Contract Liability [Roll Forward]

No definition available.

Name:	tnc_ContractwithCustomerContractLiabilityRollForwardRollForward
Namespace Prefix:	tnc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Contract with Customer, Liability, Contract Payments

+ References

No definition available.

+ Details

Name:	tnc_ContractwithCustomerLiabilityContractPayments
Namespace Prefix:	tnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Contract with Customer, Liability, Impact of Foreign Currency

+ References

No definition available.

+ Details

Name:	tnc_ContractwithCustomerLiabilityImpactofForeignCurrency
Namespace Prefix:	tnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Contract with Customer, Liability, Increase (Decrease) for Sales Incentive Accruals

+ References

No definition available.

+ Details

Name:	tnc_ContractwithCustomerLiabilityIncreaseDecreaseforSalesIncentiveAccruals
Namespace Prefix:	tnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of liability for consideration received or receivable from customer which is not included in transaction price, when consideration is expected to be refunded to customer.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 55
-Paragraph 27
-URI http://asc.fasb.org/extlink&oid=118944142&loc=SL49130611-203046-203046

+ Details

Name:	us-gaap_ContractWithCustomerRefundLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of liability for consideration received or receivable from customer which is not included in transaction price, when consideration is expected to be refunded to customer, classified as current.

+ References

+ Details

Name:	us-gaap_ContractWithCustomerRefundLiabilityCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant