v3.26.1
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) income (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)
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) income 26,900,000          
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax (25,300,000)          
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax 700,000          
Deferred gain (loss) on hedging activity, net of tax 2,200,000          
Ending shareholders' equity at Mar. 31, 2025 1,513,900,000 $ 700,000 $ (979,200,000) 1,567,300,000 1,102,300,000 (177,200,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]            
Treasury Stock, Common, Shares     (16,800,000)      
Common shares, issued (in shares)   65,200,000        
Beginning 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]            
Net (loss) income 29,000,000.0       29,000,000.0  
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax 23,000,000.0         23,000,000.0
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax 300,000         300,000
Deferred gain (loss) on hedging activity, net of tax (2,800,000)         (2,800,000)
Dividends declared to common shareholders (7,600,000)       (7,600,000)  
Treasury shares repurchased (in usd) (35,200,000)   $ (35,200,000)      
Treasury shares repurchased (in shares)     (1,100,000)      
Activity under share plans (shares)     0      
Activity under share plans (in usd) 6,200,000   $ 700,000      
APIC activity under share plans       5,500,000    
Ending shareholders' equity at Mar. 31, 2025 $ 1,513,900,000 $ 700,000 $ (979,200,000) 1,567,300,000 1,102,300,000 (177,200,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]            
Treasury Stock, Common, Shares     (17,900,000)      
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) income (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)
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) income (76,300,000)          
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax (8,800,000)          
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax 900,000          
Deferred gain (loss) on hedging activity, net of tax 2,700,000          
Treasury shares repurchased (in usd) $ (15,100,000)          
Treasury shares repurchased (in shares) (700,000)          
Ending shareholders' equity at Mar. 31, 2026 $ 1,448,100,000 $ 700,000 $ (997,800,000) 1,564,400,000 995,800,000 (115,000,000.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]            
Treasury Stock, Common, Shares     (18,500,000)      
Common shares, issued (in shares)   65,200,000        
Beginning 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]            
Net (loss) income (10,600,000)       (10,600,000)  
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax (12,000,000.0)         (12,000,000.0)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax 300,000         300,000
Deferred gain (loss) on hedging activity, net of tax 1,200,000         1,200,000
Dividends declared to common shareholders (7,600,000)       (7,600,000)  
Treasury shares repurchased (in usd) (15,100,000)   $ (15,100,000)      
Treasury shares repurchased (in shares)     (700,000)      
Activity under share plans (shares)     0      
Activity under share plans (in usd) 5,700,000   $ 1,900,000      
APIC activity under share plans       3,800,000    
Ending shareholders' equity at Mar. 31, 2026 $ 1,448,100,000 $ 700,000 $ (997,800,000) $ 1,564,400,000 $ 995,800,000 $ (115,000,000.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]            
Treasury Stock, Common, Shares 19,175,125   (19,200,000)      
Common shares, issued (in shares) 65,251,989 65,200,000