Quarterly Financial Information (Schedule of Quarterly Financial Information) (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
Quarterly Financial Information [Abstract]
Revenues	$ 5,435	$ 6,867	$ 7,066	$ 6,867	$ 6,422	$ 4,280	$ 5,260	$ 6,069	$ 26,235	$ 22,031
Gross profit	(471)	2,379	106	1,980	1,779	278	1,249	1,818	3,994	5,124
Net (loss) income before income tax	(2,459)	63	(5,065)	(2,081)	(1,087)	(2,587)	(2,322)	(1,999)	(9,542)	(7,995)
Net (loss) income	$ (2,459)	$ 63	$ (5,065)	$ (2,081)	$ (875)	$ (2,587)	$ (2,322)	$ (1,999)	$ (9,542)	$ (7,783)
Net loss per share: Basic	$ (0.05)		$ (0.11)	$ (0.05)	$ (0.03)	$ (0.09)	$ (0.08)	$ (0.06)	$ (0.21)	$ (0.23)
Net loss per share: Diluted	$ (0.05)		$ (0.11)	$ (0.05)	$ (0.03)	$ (0.09)	$ (0.08)	$ (0.06)	$ (0.21)	$ (0.23)
Weighted average common shares outstanding - Basic	45,161,273	45,149,717	45,111,273	42,255,189	34,989,530	34,972,589	33,019,478	31,628,997	44,429,114	33,661,727
Weighted average number of shares outstanding - diluted	45,161,273	45,265,370	45,111,273	42,255,189	34,989,530	34,972,589	33,019,478	31,628,997	44,429,114	33,661,727
Change in fair value of common stock warrant liability						$ 405	$ (51)		$ 2,194	$ 1,089