Income Taxes - Schedule of Reconciliation Difference of Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Amount at statutory U.S. federal income tax rate	$ (1,845)	$ 2,461	$ 5,932
Change because of the following items:
State income taxes, net of federal benefit	(724)	(13)	142
Stock-based compensation	(2,063)	330	(607)
Valuation allowance change	960	665	(2,500)
Tax reserve change	158	(52)	258
Federal manufacturing deduction		(313)	(280)
U.S. Federal and foreign research and development credits	(1,710)	(706)	(571)
Gain on strategic investment and corporate subsidiary			2,630
Foreign rate differential	371	948	622
Acquisition-related transaction costs			768
Contingent consideration expense (gain)	165	(45)	522
Unrealized foreign currency exchange (gain) loss on contingent consideration obligation	(23)	170
Federal and state rate change	1,582
Other	54	(338)	47
Income tax (benefit) provision	$ (3,075)	$ 3,107	$ 6,963

Income tax expense benefit items of income tax reconciliation.

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Income tax reconciliation acquisition related transaction costs.

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Income tax reconciliation tax contingencies unrealized foreign currency exchange loss (gain) on contingent consideration obligation.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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