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, 2021			18,535,116
Beginning 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	10.3	10.3			10.3
Other comprehensive income (loss)	(4.0)	(4.0)				(4.0)
Issue stock for directors, employee benefit and stock plans, net of related tax withholdings and repurchases (in shares)			44,700
Issue stock for directors, employee benefit and stock plans, net of related tax withholdings and repurchases of shares	(1.3)	(1.3)		(1.3)
Share-based compensation	1.8	1.8		1.8
Dividends paid per common share	(4.6)	(4.6)			(4.6)
Ending balance (in shares) at Mar. 31, 2022			18,579,816
Ending balance at Mar. 31, 2022	437.3	436.0	$ 7.0	54.6	416.3	(41.9)	1.3
Beginning balance (in shares) at Dec. 31, 2021			18,535,116
Beginning 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	42.5
Ending balance (in shares) at Sep. 30, 2022			18,596,389
Ending balance at Sep. 30, 2022	426.5	425.2	$ 7.0	57.3	439.1	(78.2)	1.3
Beginning balance (in shares) at Mar. 31, 2022			18,579,816
Beginning balance at Mar. 31, 2022	437.3	436.0	$ 7.0	54.6	416.3	(41.9)	1.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	16.6	16.6			16.6
Other comprehensive income (loss)	(16.1)	(16.1)				(16.1)
Issue stock for directors, employee benefit and stock plans, net of related tax withholdings and repurchases (in shares)			9,859
Issue stock for directors, employee benefit and stock plans, net of related tax withholdings and repurchases of shares	(0.1)	(0.1)		(0.1)
Share-based compensation	0.9	0.9		0.9
Dividends paid per common share	(4.6)	(4.6)			(4.6)
Ending balance (in shares) at Jun. 30, 2022			18,589,675
Ending balance at Jun. 30, 2022	434.0	432.7	$ 7.0	55.4	428.3	(58.0)	1.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	15.6	15.6			15.6
Other comprehensive income (loss)	(20.2)	(20.2)				(20.2)
Issue stock for directors, employee benefit and stock plans, net of related tax withholdings and repurchases (in shares)			6,714
Issue stock for directors, employee benefit and stock plans, net of related tax withholdings and repurchases of shares	0.2	0.2		0.2
Share-based compensation	1.7	1.7		1.7
Dividends paid per common share	(4.8)	(4.8)			(4.8)
Ending balance (in shares) at Sep. 30, 2022			18,596,389
Ending balance at Sep. 30, 2022	$ 426.5	425.2	$ 7.0	57.3	439.1	(78.2)	1.3
Beginning balance (in shares) at Dec. 31, 2022	18,521,485		18,521,485
Beginning balance at Dec. 31, 2022	$ 472.1	470.8	$ 7.0	56.0	458.0	(50.2)	1.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	24.3	24.3			24.3
Other comprehensive income (loss)	4.7	4.7				4.7
Issue stock for directors, employee benefit and stock plans, net of related tax withholdings and repurchases (in shares)			93,073
Issue stock for directors, employee benefit and stock plans, net of related tax withholdings and repurchases of shares	0.8	0.8		0.8
Share-based compensation	1.2	1.2		1.2
Repurchases of common stock (in shares)			(73,525)
Repurchases of common stock	(5.0)	(5.0)		(5.0)
Dividends paid per common share	(4.9)	(4.9)			(4.9)
Ending balance (in shares) at Mar. 31, 2023			18,541,033
Ending balance at Mar. 31, 2023	$ 493.2	491.9	$ 7.0	53.0	477.4	(45.5)	1.3
Beginning balance (in shares) at Dec. 31, 2022	18,521,485		18,521,485
Beginning balance at Dec. 31, 2022	$ 472.1	470.8	$ 7.0	56.0	458.0	(50.2)	1.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 78.5
Ending balance (in shares) at Sep. 30, 2023	18,521,485		18,741,371
Ending balance at Sep. 30, 2023	$ 546.3	545.0	$ 7.0	71.0	521.7	(54.7)	1.3
Beginning balance (in shares) at Mar. 31, 2023			18,541,033
Beginning balance at Mar. 31, 2023	493.2	491.9	$ 7.0	53.0	477.4	(45.5)	1.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	31.3	31.3			31.3
Other comprehensive income (loss)	1.2	1.2				1.2
Issue stock for directors, employee benefit and stock plans, net of related tax withholdings and repurchases (in shares)			69,345
Issue stock for directors, employee benefit and stock plans, net of related tax withholdings and repurchases of shares	3.4	3.4		3.4
Share-based compensation	2.7	2.7		2.7
Repurchases of common stock (in shares)			(69,780)
Repurchases of common stock	(5.0)	(5.0)		(5.0)
Dividends paid per common share	(4.9)	(4.9)			(4.9)
Ending balance (in shares) at Jun. 30, 2023			18,540,598
Ending balance at Jun. 30, 2023	521.9	520.6	$ 7.0	54.1	503.8	(44.3)	1.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	22.9	22.9			22.9
Other comprehensive income (loss)	(10.4)	(10.4)				(10.4)
Issue stock for directors, employee benefit and stock plans, net of related tax withholdings and repurchases (in shares)			222,566
Issue stock for directors, employee benefit and stock plans, net of related tax withholdings and repurchases of shares	13.9	13.9		13.9
Share-based compensation	4.7	4.7		4.7
Repurchases of common stock (in shares)			(21,793)
Repurchases of common stock	(1.7)	(1.7)		(1.7)
Dividends paid per common share	$ (5.0)	(5.0)			(5.0)
Ending balance (in shares) at Sep. 30, 2023	18,521,485		18,741,371
Ending balance at Sep. 30, 2023	$ 546.3	$ 545.0	$ 7.0	$ 71.0	$ 521.7	$ (54.7)	$ 1.3