Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit	Non- controlling Interest
Beginning balance (in shares) at Sep. 30, 2021		104,327,000
Beginning balance at Sep. 30, 2021	$ 408,822	$ 197	$ 1,053,386	$ (69)	$ (644,692)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	120,893		120,893
Exercise of stock options (in shares)		606,000
Exercise of stock options	5,185		5,185
Common stock - restricted stock units vesting (in shares)		1,027,000
Common stock - restricted stock units vesting	0	$ 1	(1)
Unrealized gains (losses) on available-for-sale securities	0
Foreign currency translation adjustments	(67)			(67)
Interest in joint venture	60,000		39,750			20,250
Net loss	(176,494)				(176,063)	(431)
Ending balance (in shares) at Sep. 30, 2022		105,960,000
Ending balance at Sep. 30, 2022	418,339	$ 198	1,219,213	(136)	(820,755)	19,819
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	78,130		78,130
Exercise of stock options (in shares)		439,000
Exercise of stock options	3,054	$ 1	3,053
Common stock - restricted stock units vesting (in shares)		913,000
Common stock - restricted stock units vesting	0	$ 1	(1)
Unrealized gains (losses) on available-for-sale securities	(2,964)			(2,964)
Foreign currency translation adjustments	(122)			(122)
Net loss	(209,275)				(205,275)	(4,000)
Ending balance (in shares) at Sep. 30, 2023		107,312,000
Ending balance at Sep. 30, 2023	287,162	$ 200	1,300,395	(3,222)	(1,026,030)	15,819
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	$ 73,968		73,968
Exercise of stock options (in shares)	226,004	226,000
Exercise of stock options	$ 2,389		2,389
Common stock - restricted stock units vesting (in shares)		1,048,000
Common stock - restricted stock units vesting	0	$ 1	(1)
Common stock issued, net of offering costs (in shares)		15,790,000
Common stock issued, net of offering costs	429,265	$ 16	429,249
Unrealized gains (losses) on available-for-sale securities	3,775			3,775
Foreign currency translation adjustments	4,197			4,197
Net loss	(609,693)				(599,493)	(10,200)
Ending balance (in shares) at Sep. 30, 2024		124,376,000
Ending balance at Sep. 30, 2024	$ 191,063	$ 217	$ 1,806,000	$ 4,750	$ (1,625,523)	$ 5,619