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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

X

- Definition

Revenue from contracts with customers line items.

+ References

No definition available.

+ Details

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-42

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition

Amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time, classified as current.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479837/606-10-45-3

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
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-Paragraph 8
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-8

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