Income Taxes - Schedule of Deferred Income Taxes (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Depreciable assets	$ (3,335)	$ (2,257)
Accruals and reserves	1,123	1,153
Stock-based compensation	3,370	3,113
Impaired strategic investments	2,701	2,701
NOL carryforwards	3,627	3,324
U.S. Federal and state R&D credits	242	110
Other	810	730
Valuation allowance	(4,511)	(3,847)
Total deferred tax assets	$ 4,027	$ 5,027