Supplementary Data - Selected Quarterly Financial Data (Detail) - USD ($)	3 Months Ended								12 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2017		Sep. 30, 2016		Sep. 30, 2015
Quarterly Financial Information Disclosure [Abstract]
Net revenue	$ 18,556,000	$ 23,743,000	$ 22,526,000	$ 15,783,000	$ 14,792,000	$ 19,863,000	$ 22,078,000	$ 13,258,000	$ 80,608,000		$ 69,991,000		$ 39,230,000
Gross Profit	3,662,000	6,690,000	6,657,000	4,150,000	3,651,000	5,151,000	5,441,000	3,282,000	21,159,000		17,525,000		7,506,000
Other income (expense), net	748,000	(72,000)	818,000	448,000	327,000	563,000	(285,000)	979,000	1,942,000		1,584,000		(2,752,000)
Net income	$ 1,021,000	$ 2,588,000	$ 3,415,000	$ 1,394,000	$ 1,724,000	$ 2,114,000	$ 1,630,000	$ 1,575,000	$ 8,418,000		$ 7,043,000		$ (1,819,000)
Net income per common share:
Basic	$ 0.07	$ 0.18	$ 0.24	$ 0.10	$ 0.12	$ 0.15	$ 0.11	$ 0.11	$ 0.58	[1]	$ 0.49	[1]	$ (0.13)	[1]
Diluted	$ 0.07	$ 0.18	$ 0.23	$ 0.10	$ 0.12	$ 0.15	$ 0.11	$ 0.11	$ 0.57	[1]	$ 0.48	[1]	$ (0.13)	[1]
Weighted-average common shares outstanding
Basic	14,414,000	14,400,000	14,390,000	14,380,000	14,368,000	14,333,000	14,320,000	14,307,000	14,396,000		14,334,000		14,283,000
Diluted	14,700,000	14,699,000	14,597,000	14,589,000	14,616,000	14,550,000	14,489,000	14,425,000	14,680,000		14,524,000		14,283,000

[1] 2016 and 2015 adjusted for three-for-two stock split