Income Taxes - Schedule of Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Current provision (benefit):
U.S. Federal	$ 263	$ (1,570)	$ 1,355
U.S. State	108	42	192
International	87	90	41
Total current provision (benefit)	458	(1,438)	1,588
Deferred provision (benefit):
U.S. Federal	1,851	(1,336)	(1,505)
U.S. State	(62)	197	(117)
International	(138)
Total deferred benefit	1,651	(1,139)	(1,622)
Total income tax provision (benefit)	$ 2,109	$ (2,577)	$ (34)