Unaudited Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 15,827	$ 16,070	$ 11,847	$ 12,791	$ 13,386	$ 13,548	$ 9,741	$ 8,491	$ 56,535	$ 45,166	$ 55,161
Cost of sales	9,926	10,654	8,125	7,766	7,761	8,498	6,116	4,769	36,471	27,144	36,367
Net income (loss) from continuing operations	900	1,055	(1,679)	(191)	1,004	(178)	(5,585)	(1,776)	85	(6,535)	(14,588)
Loss from discontinued operations	(4)	(10)	(74)	(25)	(1,676)	(239)	(1,269)	(730)	(113)	(3,914)	(2,800)
Net loss	$ 896	$ 1,045	$ (1,753)	$ (216)	$ (672)	$ (417)	$ (6,854)	$ (2,506)	$ (28)	$ (10,449)	$ (17,388)
Basic loss per common share
Continuing operations (in dollars per share)	$ 0.04	$ 0.04	$ (0.07)	$ (0.01)	$ 0.04	$ (0.01)	$ (0.24)	$ (0.07)	$ 0.00	$ (0.28)	$ (0.62)
Discontinued operations (in dollars per share)	0.00	0.00	0.00	0.00	(0.07)	(0.01)	(0.05)	(0.03)	0.00	(0.16)	(0.12)
Basic (in dollars per share)	0.04	0.04	(0.07)	(0.01)	(0.03)	(0.02)	(0.29)	(0.10)	0.00	(0.44)	(0.01)
Diluted net loss per common share
Continuing operations (in dollars per share)	0.04	0.04	(0.07)	(0.01)	0.04	(0.01)	(0.24)	(0.07)	0.00	(0.28)	(0.62)
Discontinued operations (in dollars per share)	0.00	0.00	0.00	0.00	(0.07)	(0.01)	(0.05)	(0.03)	0.00	(0.16)	(0.12)
Diluted (in dollars per share)	$ 0.04	$ 0.04	$ (0.07)	$ (0.01)	$ (0.03)	$ (0.02)	$ (0.29)	$ (0.10)	$ 0.00	$ (0.44)	$ (0.74)