Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 506	$ 821	$ 2,806	$ 3,474
Other comprehensive income (loss):
Unrealized holding gains (losses) on available-for-sale securities, net of tax	4		50	(2)
Foreign currency translation adjustments	660	1,320	(1,594)	1,728
Other comprehensive income (loss)	664	1,320	(1,544)	1,726
Comprehensive income	$ 1,170	$ 2,141	$ 1,262	$ 5,200