Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 8,087	$ 1,462	$ 7,813	$ 1,610
Other comprehensive (loss) income:
Net changes related to available-for-sale securities, net of tax	(7)	(174)	(7)	(179)
Foreign currency translation adjustments	(1,768)	(768)	64	273
Other comprehensive (loss) income	(1,775)	(942)	57	94
Comprehensive income	$ 6,312	$ 520	$ 7,870	$ 1,704