v3.25.2
Financial Instruments and Risk Management - Narrative (Details)
3 Months Ended 9 Months Ended 12 Months Ended
Jun. 30, 2025
USD ($)
derivative_instrument
Contract
Jun. 30, 2024
USD ($)
Jun. 30, 2025
USD ($)
derivative_instrument
Contract
Jun. 30, 2024
USD ($)
Sep. 30, 2024
USD ($)
Dec. 22, 2024
USD ($)
Feb. 22, 2023
Jan. 22, 2021
USD ($)
Derivative [Line Items]                
Portion or pre-tax gain included in AOCI expected to be included in earnings $ (7,500,000)   $ (7,500,000)          
Unrecognized pre-tax loss     29,800,000   $ (39,800,000)      
Impairment of intangible assets 0 $ 110,600,000 0 $ 110,600,000        
Interest Rate Contracts                
Derivative [Line Items]                
Fixed interest rate             1.042%  
Notional value decrease each year           $ 100,000,000.0    
Notional value 600,000,000.0   600,000,000.0         $ 600,000,000.0
Line of Credit | Senior Secured Term Loan B Facility, net of discount, due 2022                
Derivative [Line Items]                
Face amount of debt 880,000,000.0   880,000,000.0          
Estimate of Fair Value                
Derivative [Line Items]                
Fair market value of fixed rate long-term debt 2,354,300,000   2,354,300,000   2,305,500,000      
Reported Value Measurement                
Derivative [Line Items]                
Fair market value of fixed rate long-term debt 2,441,200,000   2,441,200,000   2,398,800,000      
Designated as Hedging Instrument | Cash Flow Hedging                
Derivative [Line Items]                
Derivatives - Foreign Currency contracts 21,300,000   21,300,000   39,200,000      
Designated as Hedging Instrument | Cash Flow Hedging | Zinc contracts                
Derivative [Line Items]                
Notional value 31,000,000   31,000,000          
Derivatives - Foreign Currency contracts $ (800,000)   $ (800,000)   4,000,000.0      
Derivative, number of open contracts | Contract 16   16          
Designated as Hedging Instrument | Cash Flow Hedging | Foreign currency contracts                
Derivative [Line Items]                
Notional value $ 152,000,000   $ 152,000,000          
Derivatives - Foreign Currency contracts $ (7,700,000)   $ (7,700,000)   (4,600,000)      
Number of open contracts | derivative_instrument 58   58          
Not Designated as Hedging Instrument | Foreign currency contracts                
Derivative [Line Items]                
Derivatives - Foreign Currency contracts $ 2,400,000   $ 2,400,000   $ 2,900,000      
Not Designated as Hedging Instrument | Foreign currency contracts                
Derivative [Line Items]                
Notional value $ 141,000,000   $ 141,000,000          
Number of open contracts | derivative_instrument 8   8