Schedule II - Valuation and Qualifying Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 537	$ 310	$ 307
Charged to Costs and Expenses	34	347	39
Deductions	(75)	(100)	(32)
Other	17	(20)	(4)
Balance at End of Period	513	537	310
Inventory Realizability Reserves [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	2,441	1,971	2,059
Charged to Costs and Expenses	1,775	930	321
Deductions	(564)	(448)	(405)
Other	(23)	(12)	(4)
Balance at End of Period	3,629	2,441	1,971
Valuation Allowances - Deferred Taxes [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	408	302	342
Charged to Costs and Expenses		106
Deductions	(106)		(40)
Other		0
Balance at End of Period	$ 302	$ 408	$ 302