Condensed Consolidated Statement of Changes in Shareholders' Equity Statement - USD ($)	Total	Common shares	Treasury Stock, Common	Additional paid-in capital	Retained earnings	Accumulated other comprehensive loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury Stock, Common, Shares			(16,300,000)
Common shares, issued (in shares)		65,200,000
Beginning shareholders' equity at Sep. 30, 2024	$ 1,584,100,000	$ 700,000	$ (937,900,000)	$ 1,586,000,000	$ 1,090,100,000	$ (154,800,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(2,100,000)				(2,100,000)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(48,300,000)					(48,300,000)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	400,000					400,000
Deferred gain (loss) on hedging activity, net of tax	5,000,000.0					5,000,000.0
Dividends declared to common shareholders	(7,100,000)				(7,100,000)
Treasury shares repurchased (in usd)	(30,100,000)		$ (30,100,000)
Treasury shares repurchased (in shares)			(800,000)
Activity under share plans (shares)			300,000
Activity under share plans (in usd)	(900,000)		$ 23,300,000
APIC activity under share plans				(24,200,000)
Ending shareholders' equity at Dec. 31, 2024	$ 1,501,000,000	$ 700,000	$ (944,700,000)	1,561,800,000	1,080,900,000	(197,700,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury Stock, Common, Shares			(16,800,000)
Common shares, issued (in shares)		65,200,000
Treasury Stock, Common, Shares	18,787,745		(18,800,000)
Common shares, issued (in shares)	65,251,989	65,200,000
Beginning shareholders' equity at Sep. 30, 2025	$ 1,553,100,000	$ 700,000	$ (1,003,300,000)	1,578,800,000	1,086,700,000	(109,800,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(65,700,000)				65,700,000
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	3,200,000					3,200,000
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	600,000					600,000
Deferred gain (loss) on hedging activity, net of tax	1,500,000					1,500,000
Dividends declared to common shareholders	(7,000,000.0)				(7,000,000.0)
Treasury shares repurchased (in usd)	0		$ 0
Treasury shares repurchased (in shares)			0
Stock Issued During Period, Shares, Period Increase (Decrease)	500,000
Activity under share plans (shares)			300,000
Activity under share plans (in usd)			$ 18,700,000
APIC activity under share plans				(18,200,000)
Ending shareholders' equity at Dec. 31, 2025	$ 1,486,200,000	$ 700,000	$ (984,600,000)	$ 1,560,600,000	$ 1,014,000,000	$ (104,500,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury Stock, Common, Shares	18,535,384		(18,500,000)
Common shares, issued (in shares)	65,251,989	65,200,000