Leases (Tables)

12 Months Ended

Sep. 30, 2023

Leases [Abstract]

Schedule of Lease Assets and Liabilities and Lease Cost

The components of lease assets and liabilities along with their classification on the Company’s consolidated balance sheets were as follows:

		September 30,
Lease Assets and Liabilities	Classification	2023		2022
		(in thousands)
Operating lease assets	Right-of-use assets	$	45,297	$	58,291
Current operating lease liabilities	Lease liabilities	10,563		2,776
Non-current operating lease liabilities	Lease liabilities, net of current portion	104,608		78,800

The components of lease cost along with its classification on the Company’s consolidated statements of operations were as follows:

		Year Ended September 30,
Lease Cost	Classification	2023		2022		2021
		(in thousands)
Operating lease cost	Research and development	$	10,350	$	7,278	$	3,649
	General and administrative expense	1,730		1,757		1,498
Variable lease cost(1)	Research and development	1,179		728		814
	General and administrative expense	—		—		1
Total		$	13,259	$	9,763	$	5,962

(1) Variable lease cost is primarily related to operating expenses associated with the Company’s operating leases.

Summary of Maturities of Operating Lease Liabilities on an Undiscounted Basis

The following table presents maturities of operating lease liabilities on an undiscounted basis as of September 30, 2023:

Year	Amounts
	(in thousands)
2024	$	10,735
2025	15,000
2026	15,341
2027	14,514
2028	13,156
2029 and thereafter	124,951
Total	$	193,697
Less imputed interest	(78,526)
Total operating lease liabilities	$	115,171

Supplemental cash flow and other information related to leases was as follows:

	Year Ended September 30,
	2023			2022			2021
	(in thousands)
Cash received for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	48,391		$	—		$	—
Right-of-use assets obtained in exchange for amended operating lease liabilities	$	17,071		$	—		$	—
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	5,204		$	4,500		$	3,100
Weighted-average remaining lease term (in years)	13.5			7			8
Weighted-average discount rate	8.0		%	8.5		%	8.5		%