Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ 7,592	$ (4,457)	$ 3,926
Other comprehensive (loss) income:
Unrealized holding gains (losses) on available-for-sale securities, net of tax	64	(38)	49
Foreign currency translation adjustments	(2,386)	(661)	2,095
Other comprehensive (loss) income	(2,322)	(699)	2,144
Comprehensive income (loss)	$ 5,270	$ (5,156)	$ 6,070