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, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 24,300	$ 17,219	$ 21,745	$ 24,001	$ 25,241	$ 17,717	$ 18,623	$ 24,036	$ 87,265	$ 85,617	$ 122,895
Cost of revenue	24,532	13,515	15,936	18,193	20,813	16,519	13,676	16,122	72,176	67,130	80,361
Gross profit	(232)	3,704	5,809	5,808	4,428	1,198	4,947	7,914	15,089	18,487	42,534
Operating expense:
Selling, general, and administrative	8,217	9,288	6,996	7,593	5,532	5,237	5,644	4,819	32,094	21,232	22,246
Research and development	6,435	4,629	4,360	4,019	4,372	3,915	3,300	3,800	19,443	15,387	12,542
(Gain) loss from change in estimate on ARO obligation	26	0	(40)	0	145	0	0	0	(14)	145	(45)
Loss (gain) on sale of assets	(302)	0	0	0	(5)	0	(68)	107	(302)	34	(456)
Total operating expense	14,376	13,917	11,316	11,612	10,044	9,152	8,876	8,726	51,221	36,798	34,793
Operating loss	(14,608)	(10,213)	(5,507)	(5,804)	(5,616)	(7,954)	(3,929)	(812)	(36,132)	(18,311)	7,741
Other income:
Interest income, net	39	99	224	267	243	216	163	111	629	733	245
Foreign exchange (loss) gain	(396)	(349)	304	14	(570)	(676)	526	286	(427)	(434)	82
Other income	0	0	0	0	110	0	0	0	0	110	316
Total other (loss) income	(357)	(250)	528	281	(217)	(460)	689	397	202	409	643
Loss before income tax (expense) benefit	(14,965)	(10,463)	(4,979)	(5,523)	(5,833)	(8,414)	(3,240)	(415)	(35,930)	(17,902)	8,384
Income tax (expense) benefit	(10)	(14)	(15)	(15)	(53)	0	169	333	(54)	449	(163)
(Loss) income from continuing operations	$ (14,975)	$ (10,477)	$ (4,994)	$ (5,538)					(35,984)	(17,453)	8,221
Net loss					$ (5,886)	$ (8,414)	$ (3,071)	$ (82)	$ (35,984)	$ (17,453)	$ 8,235
Per share data:
Net (loss) income per basic and fully diluted share (in usd per share)	$ (0.52)	$ (0.37)	$ (0.18)	$ (0.20)	$ (0.21)	$ (0.31)	$ (0.11)	$ 0.00	$ (1.29)	$ (0.64)	$ 0.31
Weighted-average number of basic and diluted shares outstanding (in shares)	28,734	28,005	27,652	27,534	27,424	27,387	27,197	27,032	27,983	27,266	26,659