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Revenue - Additional Information (Details) - USD ($) $ in Millions | 6 Months Ended |
--- | --- | ---
Mar. 31, 2025 | Sep. 30, 2024
Product Concentration Risk [Member] | Sales Revenue [Member] | Minimum [Member] |  |
Revenue From Contracts With Customers [Line Items] |  |
Concentration risk percentage | 10.00% |
Cellulosics [Member] | Product Concentration Risk [Member] | Sales Revenue [Member] |  |
Revenue From Contracts With Customers [Line Items] |  |
Concentration risk percentage | 24.00% |
Polyvinylpyrrolidones (PVP) [Member] | Product Concentration Risk [Member] | Sales Revenue [Member] |  |
Revenue From Contracts With Customers [Line Items] |  |
Concentration risk percentage | 39.00% |
Trade Receivable [Member] |  |
Revenue From Contracts With Customers [Line Items] |  |
Trade receivables | $ 189 | $ 206

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