Schedule II - Valuation and Qualifying Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 307	$ 334	$ 248
Charged to Costs and Expenses	39	90	139
Deductions	(32)	(134)	(69)
Other	(4)	17	16
Balance at End of Period	310	307	334
Inventory Realizability Reserves [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	2,059	2,680	2,456
Charged to Costs and Expenses	321	35	1,285
Deductions	(405)	(661)	(1,072)
Other	(4)	5	11
Balance at End of Period	1,971	2,059	2,680
Valuation Allowances - Deferred Taxes [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	342	342	15
Charged to Costs and Expenses			327
Deductions	(40)
Balance at End of Period	$ 302	$ 342	$ 342