Nature of Operations and Summary of Significant Accounting Policies - Schedule of Changes in Allowance for Slow Moving and Obsolete Inventories (Detail) - USD ($)	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Inventory Disclosure [Abstract]
Balance, beginning of year	$ 4,700,000	$ 4,543,000
Charged to cost of sales	401,000	304,000
Disposal of inventory, net of recoveries	(484,000)	(147,000)
Balance, end of year	$ 4,617,000	$ 4,700,000