Note 11 - Stock Options and Restricted Stock - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017
Outstanding (in shares)	2,544,665	4,814,434
Outstanding, weighted average exercise price (in dollars per share)	$ 0.85	$ 0.71
Outstanding, weighted average remaining contractual life (Year)	1 year 346 days	2 years 197 days		3 years 167 days
Outstanding, aggregate intrinsic value		$ 93		$ 1,007
Granted (in shares)	0	0
Exercised (in shares)	0	(1,230,002)
Exercised, weighted average exercise price (in dollars per share)		$ 0.44
Forfeited or Expired (in shares)	(599,332)	(1,039,767)	[1]
Forfeited or Expired, weighted average exercise price (in dollars per share)	$ 1.78	$ 0.71
Granted, weighted average exercise price (in dollars per share)
Outstanding (in shares)	1,945,333	2,544,665		4,814,434
Outstanding, weighted average exercise price (in dollars per share)	$ 0.55	$ 0.85		$ 0.71
Vested at December 31, 2019 (in shares)	1,892,332
Vested at December 31, 2018, weighted average exercise price (in dollars per share)	$ 0.56
Vested at December 31, 2018, weighted average remaining contractual life (Year)	1 year 343 days
Vested at December 31, 2018, aggregate intrinsic value
Exercisable (in shares)	1,892,332
Exercisable, weighted average exercise price (in dollars per share)	$ 0.56
Exercisable, weighted average remaining contractual life (Year)	1 year 343 days
Exercisable, aggregate intrinsic value

[1] 1,230,002 shares exercised using the cashless option resulted in 663,938 shares of common stock being issued.