Separate Financial Information of Guarantor Subsidiaries Condensed Consolidated Statements of Operations (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenues	$ 252.1	$ 262.5
Cost of Sales	(148.0)	(154.3)
Gross Profit	104.1	108.2
Operating Expense:
Research and Development Expense	7.4	7.2
Selling and Administrative Expense	82.3	90.2
Total Operating Expense	89.7	97.4
Profit from Operations	14.4	10.8
Other Income (Expense):
Equity in Earnings of Affiliates	0.0	0.0
Interest (Expense) Income, Net	(4.2)	(4.2)
Intercompany Interest Income (Expense)	0.0	0.0
Net Foreign Currency Transaction Losses	(4.1)	0.2
Other Income (Expense), Net	0.2	(0.2)
Total Other Expense, Net	(8.1)	(4.2)
Profit Before Income Taxes	6.3	6.6
Income Tax Expense	1.1	1.2
Net Earnings Including Noncontrolling Interest	5.2	5.4
Net Earnings Attributable to Tennant Company	5.2	5.4
Eliminations
Revenues	(136.6)	(135.7)
Cost of Sales	136.4	134.0
Gross Profit	(0.2)	(1.7)
Operating Expense:
Research and Development Expense	0.0	0.0
Selling and Administrative Expense	0.0	0.0
Total Operating Expense	0.0	0.0
Profit from Operations	(0.2)	(1.7)
Other Income (Expense):
Equity in Earnings of Affiliates	(0.9)	(2.5)
Interest (Expense) Income, Net	0.0	0.0
Intercompany Interest Income (Expense)	0.0	0.0
Net Foreign Currency Transaction Losses	0.0	0.0
Other Income (Expense), Net	0.0	0.0
Total Other Expense, Net	(0.9)	(2.5)
Profit Before Income Taxes	(1.1)	(4.2)
Income Tax Expense	(1.0)	(2.1)
Net Earnings Including Noncontrolling Interest	(0.1)	(2.1)
Net Earnings Attributable to Tennant Company	(0.1)	(2.1)
Parent
Revenues	116.9	116.5
Cost of Sales	(76.4)	(76.5)
Gross Profit	40.5	40.0
Operating Expense:
Research and Development Expense	5.9	5.6
Selling and Administrative Expense	27.4	27.2
Total Operating Expense	33.3	32.8
Profit from Operations	7.2	7.2
Other Income (Expense):
Equity in Earnings of Affiliates	0.0	0.3
Interest (Expense) Income, Net	(4.2)	(4.2)
Intercompany Interest Income (Expense)	3.4	3.5
Net Foreign Currency Transaction Losses	0.0	0.0
Other Income (Expense), Net	(0.1)	(0.2)
Total Other Expense, Net	(0.9)	(0.6)
Profit Before Income Taxes	6.3	6.6
Income Tax Expense	1.1	1.2
Net Earnings Including Noncontrolling Interest	5.2	5.4
Net Earnings Attributable to Tennant Company	5.2	5.4
Guarantor Subsidiaries
Revenues	150.5	148.4
Cost of Sales	(125.5)	(123.0)
Gross Profit	25.0	25.4
Operating Expense:
Research and Development Expense	0.3	0.2
Selling and Administrative Expense	18.6	19.0
Total Operating Expense	18.9	19.2
Profit from Operations	6.1	6.2
Other Income (Expense):
Equity in Earnings of Affiliates	0.5	0.8
Interest (Expense) Income, Net	0.0	0.0
Intercompany Interest Income (Expense)	(1.4)	(1.4)
Net Foreign Currency Transaction Losses	(0.1)	0.0
Other Income (Expense), Net	(0.3)	(0.4)
Total Other Expense, Net	(1.3)	(1.0)
Profit Before Income Taxes	4.8	5.2
Income Tax Expense	1.1	1.1
Net Earnings Including Noncontrolling Interest	3.7	4.1
Net Earnings Attributable to Tennant Company	3.7	4.1
Non-Guarantor Subsidiaries
Revenues	121.3	133.3
Cost of Sales	(82.5)	(88.8)
Gross Profit	38.8	44.5
Operating Expense:
Research and Development Expense	1.2	1.4
Selling and Administrative Expense	36.3	44.0
Total Operating Expense	37.5	45.4
Profit from Operations	1.3	(0.9)
Other Income (Expense):
Equity in Earnings of Affiliates	0.4	1.4
Interest (Expense) Income, Net	0.0	0.0
Intercompany Interest Income (Expense)	(2.0)	(2.1)
Net Foreign Currency Transaction Losses	(4.0)	0.2
Other Income (Expense), Net	0.6	0.4
Total Other Expense, Net	(5.0)	(0.1)
Profit Before Income Taxes	(3.7)	(1.0)
Income Tax Expense	(0.1)	1.0
Net Earnings Including Noncontrolling Interest	(3.6)	(2.0)
Net Earnings Attributable to Tennant Company	$ (3.6)	$ (2.0)