Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Revenues	$ 6,452	$ 16,070	$ 25,555	$ 40,708
Costs and expenses:
Cost of sales	3,563	10,654	14,754	26,545
Selling, general and administrative	3,822	4,105	12,735	13,789
Restructuring charge	0	0	625	0
Research and development	352	265	823	814
Intangible assets abandonment	76	0	127	317
Costs and expenses:	7,813	15,024	29,064	41,465
Operating income (loss) from continuing operations	(1,361)	1,046	(3,509)	(757)
Interest expense	(4)	0	(8)	0
Interest income	19	1	30	3
Other expense	71	8	(1)	(59)
Income (loss) from continuing operations before income taxes	(1,275)	1,055	(3,488)	(813)
Income tax expense	(21)	0	(23)	(2)
Net income (loss) from continuing operations	(1,296)	1,055	(3,511)	(815)
Income (loss) from discontinued operations (net of income tax benefit of $0 in 2019 and 2018)	18	(10)	(1)	(109)
Net income (loss)	$ (1,278)	$ 1,045	$ (3,512)	$ (924)
Basic
Continuing operations (in dollars per share)	$ (0.05)	$ 0.04	$ (0.15)	$ (0.04)
Discontinued operations (in dollars per share)	0.00	0.00	0.00	0.00
Basic net loss per common share (in dollars per share)	(0.05)	0.04	(0.15)	(0.04)
Diluted
Continuing operations (in dollars per share)	(0.05)	0.04	(0.15)	(0.04)
Discontinued operations (in dollars per share)	0.00	0.00	0.00	0.00
Diluted net loss per common share (in dollars per share)	$ (0.05)	$ 0.04	$ (0.15)	$ (0.04)
Weighted-average number of common shares outstanding:
Basic (in shares)	24,187,000	24,171,000	24,183,000	24,162,000
Diluted (in shares)	24,187,000	24,588,000	24,183,000	24,162,000