Property and Equipment - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Sep. 30, 2022
Property, Plant and Equipment [Abstract]
Computers, software, office equipment and furniture	$ 2,198	$ 2,182
Land	2,996	2,996
Research equipment	50,472	38,283
Leasehold improvements	96,344	42,017
Construction in progress	118,279	56,373
Property and equipment, gross	270,289	141,851
Less: Accumulated depreciation and amortization	(38,920)	(31,554)
Property and equipment, net	$ 231,369	$ 110,297