Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 4,237	$ 1,123	$ 7,592
Other comprehensive (loss) income:
Net changes related to available-for-sale securities, net of tax	1	(10)	64
Foreign currency translation adjustments	(1,448)	2,788	(2,386)
Other comprehensive (loss) income	(1,447)	2,778	(2,322)
Comprehensive income	$ 2,790	$ 3,901	$ 5,270