Consolidated Statements of Equity - USD ($) $ in Millions	Total	Tennant Company Shareholders' Equity	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Noncontrolling Interest
Beginning balance (in shares) at Dec. 31, 2019			18,336,010
Beginning balance at Dec. 31, 2019	$ 361.3	$ 359.9	$ 6.9	$ 45.5	$ 346.0	$ (38.5)	$ 1.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	33.7	33.7			33.7
Other comprehensive (loss) income	18.4	18.4				18.4
Issue stock for directors, employee benefit and stock plans, net of related tax withholdings (in shares)			167,795
Issue stock for directors, employee benefit and stock plans, net of related tax withholdings	3.3	3.3		3.3
Share-based compensation	6.0	6.0		6.0
Dividends paid per common share	(16.3)	(16.3)			(16.3)
Purchase of noncontrolling interests	(0.1)	(0.1)		(0.1)
Other	(0.2)	(0.1)			(0.1)		(0.1)
Ending balance (in shares) at Dec. 31, 2020			18,503,805
Ending balance at Dec. 31, 2020	406.1	404.8	$ 6.9	54.7	363.3	(20.1)	1.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	64.9	64.9			64.9
Other comprehensive (loss) income	(17.8)	(17.8)				(17.8)
Issue stock for directors, employee benefit and stock plans, net of related tax withholdings (in shares)			228,293
Issue stock for directors, employee benefit and stock plans, net of related tax withholdings	5.0	5.0	$ 0.1	4.9
Share-based compensation	9.5	9.5		9.5
Dividends paid per common share	$ (17.5)	(17.5)			(17.5)
Repurchases of common stock (in shares)	(196,982)		(196,982)
Repurchases of common stock	$ (15.0)	(15.0)		(15.0)
Other	$ (0.1)	(0.1)			(0.1)
Ending balance (in shares) at Dec. 31, 2021	18,535,116		18,535,116
Ending balance at Dec. 31, 2021	$ 435.1	433.8	$ 7.0	54.1	410.6	(37.9)	1.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	66.3	66.3			66.3
Other comprehensive (loss) income	(12.3)	(12.3)				(12.3)
Issue stock for directors, employee benefit and stock plans, net of related tax withholdings (in shares)			66,125
Issue stock for directors, employee benefit and stock plans, net of related tax withholdings	(0.9)	(0.9)		(0.9)
Share-based compensation	7.8	7.8		7.8
Dividends paid per common share	$ (18.9)	(18.9)			(18.9)
Repurchases of common stock (in shares)	(79,756)		(79,756)
Repurchases of common stock	$ (5.0)	(5.0)		(5.0)
Ending balance (in shares) at Dec. 31, 2022	18,521,485		18,521,485
Ending balance at Dec. 31, 2022	$ 472.1	$ 470.8	$ 7.0	$ 56.0	$ 458.0	$ (50.2)	$ 1.3