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)			13,700,000
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]
Net earnings	114.7	$ 0.0	$ 0.0	0.0	114.7	0.0
Dividends, Common Stock, Cash	31.7				31.7
Foreign currency translation adjustments	44.3					44.3
Pension and postretirement activity, net of tax	6.6			0.0	0.0	6.6
Deferred gain (loss) on hedging activity, net of tax	(4.8)			0.0	0.0	(4.8)
Treasury Stock, Shares, Acquired			(1,900,000)
Repurchase of shares (in usd)	(75.2)		$ 75.2
Activity under share plans (in shares)		0	600,000
Activity under share plans (in usd)	(19.5)	$ 0.0	$ (30.0)	(10.5)	0.0	0.0
Common shares, issued (in shares) at Sep. 30, 2023		65,200,000
Treasury shares (in shares) at Sep. 30, 2023			(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)			15,000,000.0
Net earnings	98.6				98.6
Dividends, Common Stock, Cash	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)
Treasury Stock, Shares, Acquired			(1,600,000)
Repurchase of shares (in usd)	(59.3)		$ 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
Net earnings	$ 25.4				25.4
Dividends, Common Stock, Cash	28.8				28.8
Foreign currency translation adjustments	27.0					27.0
Pension and postretirement activity, net of tax	17.2					17.2
Deferred gain (loss) on hedging activity, net of tax	0.8					0.8
Repurchase of shares including excise tax	$ 90.0
Treasury Stock, Shares, Acquired	(2,800,000)		(2,800,000)
Repurchase of shares (in usd)	$ (90.2)		$ 90.0
Activity under share plans (in shares)			300,000
Activity under share plans (in usd)	$ (17.4)		$ (24.6)	(7.2)
Common shares, issued (in shares) at Sep. 30, 2025	65,251,989	65,200,000
Treasury shares (in shares) at Sep. 30, 2025	(18,787,745)		(18,800,000)
Shareholders' equity at Sep. 30, 2025	$ 1,553.1	$ 0.7	$ (1,003.3)	$ 1,578.8	$ 1,086.7	$ (109.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury shares (in shares)	18,787,745		18,800,000