Income Taxes - Summary of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Sep. 30, 2020
Deferred tax assets:
Net U.S. operating loss carryforwards	$ 3,833	$ 3,543
Net non-U.S. operating loss carryforwards	637	789
Employee benefits	1,761	2,688
Inventory reserves	897	1,049
Allowance for doubtful accounts	45	73
Intangibles	1,621	2,197
Foreign tax credits	1,724	1,724
Other tax credits	1,514	1,359
Other	1,216	1,171
Total deferred tax assets	13,248	14,593
Deferred tax liabilities:
Depreciation	(7,948)	(8,653)
Prepaid expenses	(359)	(376)
Other	(458)	(1,635)
Total deferred tax liabilities	(8,765)	(10,664)
Net deferred tax assets	4,483	3,929
Valuation allowance	(4,641)	(5,329)
Net deferred tax liabilities	$ (158)	$ (1,400)