Consolidated Statement of Changes in Shareholders' Equity - USD ($) $ in Millions	Total	Common shares	Treasury shares	Additional paid-in capital	Retained earnings	Accumulated other comprehensive loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury shares (in shares)			10,900,000
Common shares, issued (in shares) at Sep. 30, 2021		65,200,000
Treasury shares (in shares) at Sep. 30, 2021			(10,900,000)
Shareholders' equity at Sep. 30, 2021	$ 1,590.8	$ 0.7	$ (776.3)	$ 1,631.1	$ 872.2	$ (136.9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	99.5	$ 0.0	$ 0.0	0.0	99.5	0.0
Dividends declared to common shareholders	(32.6)				(32.6)
Foreign currency translation adjustments	(89.4)					(89.4)
Pension and postretirement activity, net of tax	4.7			0.0	0.0	4.7
Deferred gain (loss) on hedging activity, net of tax	5.5			0.0	0.0	5.5
Treasury Stock, Shares, Acquired			(3,300,000)
Repurchase of shares (in usd)	(125.3)		$ 125.3
Activity under share plans (in shares)		0	500,000
Activity under share plans (in usd)	(13.9)	$ 0.0	$ (40.7)	(26.8)	0.0	0.0
Common shares, issued (in shares) at Sep. 30, 2022		65,200,000
Treasury shares (in shares) at Sep. 30, 2022			(13,700,000)
Shareholders' equity at Sep. 30, 2022	1,467.1	$ 0.7	$ (860.9)	1,604.3	939.1	(216.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury shares (in shares)			13,700,000
Net earnings	114.7				114.7
Dividends declared to common shareholders	(31.7)				(31.7)
Foreign currency translation adjustments	44.3					44.3
Pension and postretirement activity, net of tax	6.6					6.6
Deferred gain (loss) on hedging activity, net of tax	(4.8)					(4.8)
Treasury Stock, Shares, Acquired			(1,900,000)
Repurchase of shares (in usd)	(75.2)		$ 75.2
Activity under share plans (in shares)			600,000
Activity under share plans (in usd)	$ (19.5)		$ (30.0)	(10.5)
Common shares, issued (in shares) at Sep. 30, 2023	65,251,989	65,200,000
Treasury shares (in shares) at Sep. 30, 2023	(15,133,200)		(15,000,000.0)
Shareholders' equity at Sep. 30, 2023	$ 1,540.5	$ 0.7	$ (906.1)	1,593.8	1,022.1	(170.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury shares (in shares)	15,133,200		15,000,000.0
Net earnings	$ 98.6				98.6
Dividends declared to common shareholders	(30.6)				(30.6)
Foreign currency translation adjustments	18.6					18.6
Pension and postretirement activity, net of tax	1.2					1.2
Deferred gain (loss) on hedging activity, net of tax	(4.6)					(4.6)
Repurchase of shares including excise tax	$ 59.3
Treasury Stock, Shares, Acquired	(1,600,000)		(1,600,000)
Repurchase of shares (in usd)	$ (58.5)		$ 59.3
Activity under share plans (in shares)			300,000
Activity under share plans (in usd)	$ (19.7)		$ (27.5)	(7.8)
Common shares, issued (in shares) at Sep. 30, 2024	65,251,989	65,200,000
Treasury shares (in shares) at Sep. 30, 2024	(16,331,176)		(16,300,000)
Shareholders' equity at Sep. 30, 2024	$ 1,584.1	$ 0.7	$ (937.9)	$ 1,586.0	$ 1,090.1	$ (154.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury shares (in shares)	16,331,176		16,300,000