Property and Equipment - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Sep. 30, 2022
Property, Plant and Equipment [Abstract]
Computers, software, office equipment and furniture	$ 2,182	$ 2,182
Land	2,996	2,996
Research equipment	43,739	38,283
Leasehold improvements	42,017	42,017
Construction in progress	90,215	56,373
Property and equipment, gross	181,149	141,851
Less: Accumulated depreciation and amortization	(33,835)	(31,554)
Property and equipment, net	$ 147,314	$ 110,297