Leases - Components of Lease Costs (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2025	Mar. 31, 2024	Sep. 30, 2024	Sep. 30, 2023
Leases [Abstract]
Operating lease costs	$ 580	$ 1,154	$ 1,361	$ 2,423	$ 4,309	$ 8,517
Variable and short-term lease costs	2,260	1,672	4,646	2,961	9,545	3,691
Interest expense on finance lease liabilities		1,256	48	2,545	3,530	4,492
Amortization expense of finance lease assets		513	54	4,636	5,163	13,414
Total lease costs	$ 2,840	$ 4,595	$ 6,109	$ 12,565	$ 22,547	$ 30,114

Variable and short-term lease costs.

No definition available.

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- Definition

Amount of interest expense on finance lease liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 53
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479589/842-20-55-53

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 4
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479041/842-20-45-4

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-4

+ Details

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- Definition

Amount of amortization expense attributable to right-of-use asset from finance lease.

+ References

+ Details

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- Definition

Amount of lease cost recognized by lessee for lease contract.

+ References

+ Details

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Balance Type:	debit
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- References

No definition available.

+ Details

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- Definition

Amount of single lease cost, calculated by allocation of remaining cost of lease over remaining lease term. Includes, but is not limited to, single lease cost, after impairment of right-of-use asset, calculated by amortization of remaining right-of-use asset and accretion of lease liability.

+ References

+ Details

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