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, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 25,241	$ 17,717	$ 18,623	$ 24,036	$ 29,176	$ 30,952	$ 32,591	$ 30,176	$ 85,617	$ 122,895	$ 91,998
Cost of revenue	20,813	16,519	13,676	16,122	18,565	20,110	21,553	20,133	67,130	80,361	61,044
Gross profit	4,428	1,198	4,947	7,914	10,611	10,842	11,038	10,043	18,487	42,534	30,954
Operating expense (income):
Selling, general, and administrative	5,532	5,237	5,644	4,819	5,181	5,815	5,672	5,578	21,232	22,246	20,734
Research and development	4,372	3,915	3,300	3,800	3,862	3,340	3,141	2,199	15,387	12,542	9,921
Impairments					38	0	468	0	0	506	0
Loss (gain) from change in estimate on ARO obligation	145	0	0	0	(45)	0	0	0	145	(45)	0
Loss (gain) on sale of assets	(5)	0	(68)	107	(134)	(322)	0	0	34	(456)	(41)
Total operating expense	10,044	9,152	8,876	8,726	8,902	8,833	9,281	7,777	36,798	34,793	28,015
Operating (loss) income	(5,616)	(7,954)	(3,929)	(812)	1,709	2,009	1,757	2,266	(18,311)	7,741	2,939
Other income (expense):
Interest income, net	243	216	163	111	99	77	46	23	733	245	88
Foreign exchange (loss) gain	(570)	(676)	526	286	388	53	44	(403)	(434)	82	(394)
Other income	110	0	0	0	0	316	0	0	110	316	0
Total other income (expense)	(217)	(460)	689	397	487	446	90	(380)	409	643	(306)
Income (loss) from continuing operations before income taxes	(5,833)	(8,414)	(3,240)	(415)	2,196	2,455	1,847	1,886	(17,902)	8,384	2,633
Income tax benefit (expense)	(53)	0	169	333	(32)	(19)	8	(120)	449	(163)	(14)
(Loss) income from continuing operations	(5,886)	(8,414)	(3,071)	(82)	2,164	2,436	1,855	1,766	(17,453)	8,221	2,619
Income from discontinued operations, net of tax	0	0	0	0	41	(11)	(7)	(9)	0	14	5,647
Undistributed earnings allocated to common shareholders for basic and diluted net income per share	$ (5,886)	$ (8,414)	$ (3,071)	$ (82)	$ 2,205	$ 2,425	$ 1,848	$ 1,757	$ (17,453)	$ 8,235	$ 8,266
Net income per basic share:
Continuing operations (in usd per share)	$ (0.21)	$ (0.31)	$ (0.11)	$ 0.00	$ 0.08	$ 0.09	$ 0.07	$ 0.07	$ (0.64)	$ 0.31	$ 0.10
Discontinued operations (in usd per share)	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.22
Net (loss) income per basic share (in usd per share)	(0.21)	(0.31)	(0.11)	0.00	0.08	0.09	0.07	0.07	(0.64)	0.31	0.32
Net income per diluted share:
Continuing operations (in usd per share)	(0.21)	(0.31)	(0.11)	0.00	0.08	0.09	0.07	0.07	(0.64)	0.30	0.10
Discontinued operations (in usd per share)	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.21
Net income per diluted share (in usd per share)	$ (0.21)	$ (0.31)	$ (0.11)	$ 0.00	$ 0.08	$ 0.09	$ 0.07	$ 0.07	$ (0.64)	$ 0.30	$ 0.31
Weighted-average number of basic and diluted shares outstanding (in shares)	27,424	27,387	27,197	27,032
Weighted-average number of basic shares outstanding (in shares)					26,904	26,833	26,622	26,279	27,266	26,659	25,979
Weighted-average number of basic shares outstanding (in shares)					27,768	27,816	27,585	27,039	27,266	27,544	26,518