GEOGRAPHIC AND SEGMENT INFORMATION - REPORTABLE SEGMENT (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended	9 Months Ended
	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2019	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Sales	$ 7,575	$ 5,629	$ 3,672	$ 12,197	$ 19,772	$ 10,760
Income (loss) from continuing operations	(4,697)		(2,796)		(14,935)	(8,449)
Interest income	327		135		1,153	135
Interest income, net			105			33
Change in value of derivative liabilities	0		0		0	20
Other income, net	230		(155)		5	(155)
Income tax (expense) benefit	(171)		2,408		(123)	2,384
Operating Segments | Advanced Energy
Segment Reporting Information [Line Items]
Sales	6,094		2,985		15,734	8,727
Income (loss) from continuing operations	(1,357)		(1,155)		(5,756)	(2,525)
Interest income	0				0
Interest income, net						0
Change in value of derivative liabilities						0
Other income, net	0				0
Income tax (expense) benefit	0		0		0	0
Operating Segments | OEM
Segment Reporting Information [Line Items]
Sales	1,481		687		4,038	2,033
Income (loss) from continuing operations	268		368		995	1,076
Interest income	0				0
Interest income, net						0
Change in value of derivative liabilities						0
Other income, net	0				0
Income tax (expense) benefit	0		0		0	0
Corporate & Other
Segment Reporting Information [Line Items]
Sales	0		0		0	0
Income (loss) from continuing operations	(3,608)		(2,009)		(10,174)	(7,000)
Interest income	327				1,153
Interest income, net			105			33
Change in value of derivative liabilities						20
Other income, net	230				5
Income tax (expense) benefit	$ (171)		$ 2,408		$ (123)	$ 2,384