Summary of Significant Accounting Policies and Supplemental Balance Sheet Information - Summary of Prepaids and Other Current Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Sep. 30, 2022
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid expenses	$ 2,600	$ 2,570
Irish research and development credits receivable	1,322	753
CARES Act employee retention credit receivable	3,441	3,441
Prepaids and other	$ 7,363	$ 6,764