Income Taxes - Schedule of Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Current (benefit) provision:
U.S. Federal	$ (1,570)	$ 1,355	$ (890)
U.S. State	42	192	51
International	90	41	41
Total current (benefit) provision	(1,438)	1,588	(798)
Deferred (benefit) provision:
U.S. Federal	(1,336)	(1,505)	(2,006)
U.S. State	197	(117)	(271)
Total deferred benefit	(1,139)	(1,622)	(2,277)
Total income tax benefit	$ (2,577)	$ (34)	$ (3,075)