Income and Other Taxes - Deferred Tax Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Federal net operating loss carryforwards	$ 96,289	$ 100,363
Foreign net operating loss carryforwards	1,372	1,680
Income tax credit carryforwards	2,510	2,671
Inventory reserves	2,229	2,320
Accounts receivable reserves	62	55
Accrued warranty reserve	269	193
State net operating loss carryforwards	6,356	5,970
Stock compensation	979	806
Deferred compensation	476	443
Fixed assets and intangibles	(497)	(348)
ROU lease liability	3,289	3,529
ROU lease assets	(3,195)	(3,467)
Other	1,372	1,322
Total deferred tax assets	111,511	115,537
Valuation allowance	(111,511)	(115,537)
Net deferred tax liabilities	$ 0	$ 0

Deferred Tax Assets, Fixed Assets And Intangibles

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from ROU lease assets.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from ROU lease liability.

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

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible domestic operating loss carryforwards. Excludes state and local operating loss carryforwards.

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

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible state and local 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 research tax credit carryforwards.

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

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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 the allowance for doubtful accounts.

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

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

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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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Amount, after deferred tax asset, of deferred tax liability attributable to taxable differences without jurisdictional netting.

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