Supplemental Balance Sheet Information - Summary of Prepaids and Other Current Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Sep. 30, 2023
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid expenses	$ 3,635	$ 2,600
Irish research and development credits receivable	662	1,322
CARES Act employee retention credit receivable	3,441	3,441
Prepaids and other	$ 7,738	$ 7,363