Nature of Operations and Summary of Significant Accounting Policies - Schedule of Changes in Accrual for Warranty and Related Costs (Detail) - USD ($)	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Product Warranty Liability [Abstract]
Balance, beginning of year	$ 401,000	$ 205,000	$ 367,000
Warranties issued	400,000	475,000	20,000
Warranties settled	(389,000)	(279,000)	(182,000)
Balance, end of year	$ 412,000	$ 401,000	$ 205,000