Business Segment Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Mar. 31, 2019 USD ($) segment	Mar. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)
Segment Reporting Information [Line Items]
Number of business segments | segment			3
Net revenues	$ 20,633	$ 21,115	$ 43,858	$ 48,231
Operating income (loss)	1,248	1,485	1,912	4,346
Identifiable assets	131,604		131,604		$ 149,406
Operating Segments | Solar
Segment Reporting Information [Line Items]
Net revenues	16,053	16,582	35,013	37,473
Operating income (loss)	1,732	2,257	4,477	5,261
Identifiable assets	60,362		60,362		59,744
Operating Segments | SiC/LED
Segment Reporting Information [Line Items]
Net revenues	3,273	3,603	6,256	7,126
Operating income (loss)	877	1,111	1,646	2,215
Identifiable assets	7,848		7,848		6,545
Operating Segments | Automation
Segment Reporting Information [Line Items]
Net revenues	1,307	930	2,589	3,632
Operating income (loss)	(116)	(483)	(340)	(36)
Identifiable assets	3,995		3,995		3,586
Non-Segment
Segment Reporting Information [Line Items]
Operating income (loss)	(1,245)	$ (1,400)	(3,871)	$ (3,094)
Identifiable assets	33,422		33,422		34,209
Discontinued Operations
Segment Reporting Information [Line Items]
Identifiable assets	$ 25,977		$ 25,977		$ 45,322