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, 2022			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, 2023	18,631,384		18,631,384
Beginning balance at Dec. 31, 2023	$ 578.3	577.0	$ 7.0	64.9	547.4	(42.3)	1.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	28.4	28.4			28.4
Other comprehensive income (loss)	(7.2)	(7.2)				(7.2)
Issue stock for directors, employee benefit and stock plans, net of related tax withholdings and repurchases (in shares)			388,179
Issue stock for directors, employee benefit and stock plans, net of related tax withholdings and repurchases of shares	19.6	19.6	$ 0.1	19.5
Share-based compensation	3.2	3.2		3.2
Repurchases of common stock (in shares)			(12,725)
Repurchases of common stock	(1.1)	(1.1)		(1.1)
Dividends paid per common share	$ (5.3)	(5.3)			(5.3)
Ending balance (in shares) at Mar. 31, 2024	18,631,384		19,006,838
Ending balance at Mar. 31, 2024	$ 615.9	$ 614.6	$ 7.1	$ 86.5	$ 570.5	$ (49.5)	$ 1.3