Income Taxes - Summary of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 30, 2019
Deferred tax assets:
Net U.S. operating loss carryforwards	$ 3,543	$ 5,002
Net non-U.S. operating loss carryforwards	789	866
Employee benefits	2,688	2,456
Inventory reserves	1,049	970
Allowance for doubtful accounts	73	144
Intangibles	2,197	2,535
Foreign tax credits	1,724	1,724
Other tax credits	1,359	1,232
Other	1,171	918
Total deferred tax assets	14,593	15,847
Deferred tax liabilities:
Depreciation	(8,653)	(8,135)
Prepaid expenses	(376)	(192)
Other	(1,635)	(1,681)
Total deferred tax liabilities	(10,664)	(10,008)
Net deferred tax assets	3,929	5,839
Valuation allowance	(5,329)	(7,557)
Net deferred tax liabilities	$ (1,400)	$ (1,718)