Quarterly report [Sections 13 or 15(d)]

Derivatives and Hedging Activities - Interest Rate Swap Contracts Reflected in Consolidated Balance Sheets (Details)

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Derivatives and Hedging Activities - Interest Rate Swap Contracts Reflected in Consolidated Balance Sheets (Details) - USD ($)
$ in Thousands
Mar. 31, 2026
Sep. 30, 2025
Interest Rate Swaps | Cash flow hedges | Designated as Hedging Instrument    
Derivatives, Fair Value [Line Items]    
Total derivatives $ (820) $ (2,338)
Cross-Currency Swaps    
Derivatives, Fair Value [Line Items]    
Advance payments received from counterparties 40,186 40,186
Cross-Currency Swaps | Net investment hedges | Designated as Hedging Instrument    
Derivatives, Fair Value [Line Items]    
Total derivatives (53,645) (58,541)
Other current assets | Interest Rate Swaps | Cash flow hedges | Designated as Hedging Instrument    
Derivatives, Fair Value [Line Items]    
Assets derivatives 197 15
Other current assets | Cross-Currency Swaps | Net investment hedges | Designated as Hedging Instrument    
Derivatives, Fair Value [Line Items]    
Assets derivatives 0 0
Other non-current assets | Interest Rate Swaps | Cash flow hedges | Designated as Hedging Instrument    
Derivatives, Fair Value [Line Items]    
Assets derivatives 148 24
Other non-current assets | Cross-Currency Swaps | Net investment hedges | Designated as Hedging Instrument    
Derivatives, Fair Value [Line Items]    
Assets derivatives 0 0
Other current liabilities | Interest Rate Swaps | Cash flow hedges | Designated as Hedging Instrument    
Derivatives, Fair Value [Line Items]    
Liability derivatives (684) (973)
Other current liabilities | Cross-Currency Swaps | Net investment hedges | Designated as Hedging Instrument    
Derivatives, Fair Value [Line Items]    
Liability derivatives (43,061) (45,914)
Other non-current liabilities | Interest Rate Swaps | Cash flow hedges | Designated as Hedging Instrument    
Derivatives, Fair Value [Line Items]    
Liability derivatives (481) (1,404)
Other non-current liabilities | Cross-Currency Swaps | Net investment hedges | Designated as Hedging Instrument    
Derivatives, Fair Value [Line Items]    
Liability derivatives $ (10,584) $ (12,627)