Leases - Components of Lease Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Lease Assets and Liabilities
Right-of-use assets	$ 43,891	$ 45,255
Lease liabilities	7,289	6,342
Lease liabilities, net of current portion	104,112	111,027
Lease Cost
Total	16,511	16,689	$ 13,259
Research and development
Lease Cost
Operating lease cost	10,483	11,035	10,350
Variable lease cost	4,076	3,648	1,179
General and administrative expense
Lease Cost
Operating lease cost	1,952	2,006	1,730
Variable lease cost	$ 0	$ 0	$ 0

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Amount of lease cost recognized by lessee for lease contract.

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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

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Present value of lessee's discounted obligation for lease payments from operating lease, classified as current.

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Present value of lessee's discounted obligation for lease payments from operating lease, classified as noncurrent.

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- Definition

Amount of lessee's right to use underlying asset under operating lease.

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Amount of variable lease cost, excluded from lease liability, recognized when obligation for payment is incurred for finance and operating leases.

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