Income Taxes - Schedule of Deferred Income Taxes (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Depreciable assets	$ (1,019)	$ (3,335)
Accruals and reserves	1,308	1,123
Stock-based compensation	1,798	3,370
Impaired strategic investments	1,687	2,701
NOL carryforwards	4,637	3,627
U.S. Federal and state R&D credits	1,896	242
Other	538	810
Valuation allowance	(4,541)	(4,511)
Total deferred tax assets	$ 6,304	$ 4,027

Deferred tax assets impaired investment.

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Deferred tax assets (liabilities) property plant and equipment.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from in-process research and development costs expensed in connection with a business combination.

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Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards classified as noncurrent.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.

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Amount, before allocation of valuation allowance, of deferred tax asset attributable to deductible temporary differences, classified as other.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from share-based compensation.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from reserves and accruals.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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