Leases - Supplemental Cash Flow and Other Information Related to Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Cash received for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 3,099	$ 48,391	$ 0
Right-of-use assets adjusted in exchange for new/amended operating lease liabilities	(29)	17,071	0
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 11,038	$ 5,204	$ 4,500
Weighted-average remaining lease term (in years)	12 years 6 months	13 years 6 months	7 years
Weighted-average discount rate	8.00%	8.00%	8.50%