Income Taxes - Schedule of Reconciliation Difference of Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Amount at statutory U.S. federal income tax rate	$ 1,333	$ (305)	$ 1,587
Change because of the following items:
State income taxes, net of federal benefit	(273)	(551)	(452)
U.S. federal and foreign R&D credits	(920)	(1,571)	(2,464)
Foreign and state rate differential	596	212	156
Valuation allowance change	1,059	825	671
Stock-based compensation	(544)	(81)	(163)
Contingent consideration expense (gain) and related foreign currency revaluation	3		(61)
U.S. Federal and state rate change	(35)	17	44
Tax reserve change	(150)	609	770
Foreign-derived income deduction		(88)	(150)
Impact of CARES Act	735	(1,700)
Acquisition-related transaction costs	187
Other	118	56	28
Total income tax provision (benefit)	$ 2,109	$ (2,577)	$ (34)

Income tax expense benefit items of income tax reconciliation.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit)attributable to (gain) expense on contingent consideration and related foreign currency valuation.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) attributable to enactment of the Coronavirus Aid, Relief and Economic Security Act (the “CARES Act”).

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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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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to increase (decrease) in the valuation allowance for deferred tax assets.

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