Selected Quarterly Financial Information (unaudited) (Summary of Selected Quarter Financial Information) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 33,530	$ 27,266	$ 23,850	$ 25,482	$ 24,300	$ 17,219	$ 21,745	$ 24,001	$ 110,128	$ 87,265	$ 85,617
Cost of revenue	21,067	18,048	17,423	18,008	24,532	13,515	15,936	18,193	74,546	72,176	67,130
Gross profit	12,463	9,218	6,427	7,474	(232)	3,704	5,809	5,808	35,582	15,089	18,487
Operating expense (income):
Selling, general, and administrative	5,669	5,936	7,139	5,887	8,243	9,288	6,956	7,593	24,631	32,080	21,377
Research and development	6,236	4,807	4,584	4,642	6,435	4,629	4,360	4,019	20,269	19,443	15,387
Gain on sale of assets	(55)	(312)	(315)	(1,602)	(302)				(2,284)	(302)	34
Total operating expense	11,850	10,431	11,408	8,927	14,376	13,917	11,316	11,612	42,616	51,221	36,798
Operating loss	613	(1,213)	(4,981)	(1,453)	(14,608)	(10,213)	(5,507)	(5,804)	(7,034)	(36,132)	(18,311)
Other income:
Interest income, net	(50)	(40)	1	(15)	39	99	224	267	(104)	629	733
Foreign exchange gain (loss)	227	(20)	(156)	147	(396)	(349)	304	14	198	(427)	(434)
Other income											110
Total other income	177	(60)	(155)	132	(357)	(250)	528	281	94	202	409
Loss before income taxes	790	(1,273)	(5,136)	(1,321)	(14,965)	(10,463)	(4,979)	(5,523)	(6,940)	(35,930)	(17,902)
Income tax (expense) benefit	(87)	(14)	55	(14)	(10)	(14)	(15)	(15)	(60)	(54)	449
Net loss	$ 703	$ (1,287)	$ (5,081)	$ (1,335)	$ (14,975)	$ (10,477)	$ (4,994)	$ (5,538)	$ (7,000)	$ (35,984)	$ (17,453)
Per share data:
Net loss per basic and diluted share (in dollars per share)	$ 0.02	$ (0.04)	$ (0.18)	$ (0.05)	$ (0.52)	$ (0.37)	$ (0.18)	$ (0.20)	$ (0.24)	$ (1.29)	$ (0.64)
Weighted-average number of basic and diluted shares outstanding	29,386	29,295	29,033	28,832	28,734	28,005	27,652	27,534	29,136	27,983	27,266