Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 825	$ 3,051	$ 3,338	$ 6,665
Other comprehensive income (loss), net of tax:
Unrealized holding losses on available-for-sale securities arising during the period		(70)	(2)	(1,156)
Reclassification adjustment for realized gains included in net income		(346)		(342)
Foreign currency translation adjustments	1,320		1,728
Other comprehensive income (loss)	1,320	(416)	1,726	(1,498)
Comprehensive income	$ 2,145	$ 2,635	$ 5,064	$ 5,167