Income Taxes - Summary of Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Income Tax Disclosure [Abstract]
Beginning of fiscal year	$ 1,216	$ 1,300	$ 1,435
Increases in tax positions for prior years	50	43	27
Decreases in tax positions for prior years	(10)	(1)	(278)
Increases in tax positions for current year	146	149	122
Lapse of the statute of limitations	(154)	(275)	(6)
End of fiscal year	$ 1,248	$ 1,216	$ 1,300