Income Taxes - Schedule of Reconciliation Difference of Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Income Tax Disclosure [Abstract]
Amount at statutory U.S. federal income tax rate	$ 5,932	$ 6,385	$ 6,465
Change because of the following items:
State income taxes, net of federal benefit	142	67	118
Stock-based compensation	(607)	16	21
Valuation allowance change	(2,500)	348	120
Tax reserve change	258	34	(121)
Federal manufacturing deduction	(280)	(268)	(235)
Federal research and development credit	(571)	(74)	(67)
Gain on strategic investment and corporate subsidiary	2,630
Foreign rate differential	622
Acquisition-related transaction costs	768
Contingent consideration accretion	522
Other	47	(214)	(36)
Income tax provision	$ 6,963	$ 6,294	$ 6,265

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 contingent consideration accretion.

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Income tax reconciliation gain on strategic investment and corporate subsidiary.

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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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