Note 20 - Quarterly Financial Information (Unaudited) - Quarterly Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Revenue	$ 597	$ 421	$ 132	$ 223	$ 144	$ 253	$ 55	$ 80	$ 1,373	$ 532
Gross profit	331	137	29	44	6	(631)	(6)	(1)	541	(632)
Operating loss	(1,159)	(1,520)	(3,333)	(1,878)	(1,974)	(2,613)	(2,177)	(2,196)	(7,890)	(8,960)
Net loss	$ (1,044)	$ (1,395)	$ (3,224)	$ (1,768)	$ (1,872)	$ (2,524)	$ (2,142)	$ (2,163)	$ (7,431)	$ (8,701)
Basic and diluted net loss per common share (in dollars per share)	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ (0.01)	$ (0.01)