Note 10 - Stock Options - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Outstanding (in shares)	4,211,168	3,485,168
Outstanding, weighted average exercise price (in dollars per share)	$ 1.09	$ 1.31
Outstanding, weighted average remaining contractual life (Year)	3 years 167 days	2 years 310 days	2 years 193 days
Outstanding, aggregate intrinsic value	$ 1,007	$ 46	$ 63
Granted (in shares)	2,971,600	3,525,000
Granted, weighted average exercise price (in dollars per share)	$ 0.32	$ 0.78
Exercised (in shares)	0	0
Forfeited or Expired (in shares)	(2,368,334)	(2,799,000)
Forfeited or Expired, weighted average exercise price (in dollars per share)	$ 0.90	$ 0.96
Outstanding (in shares)	4,814,434	4,211,168	3,485,168
Outstanding, weighted average exercise price (in dollars per share)	$ 0.71	$ 1.09	$ 1.31
Vested or Expected to Vest (in shares)	2,282,834
Vested or Expected to Vest, weighted average exercise price (in dollars per share)	$ 1.02
Vested or Expected to Vest, weighted average remaining contractual life (Year)	2 years 281 days
Vested or Expected to Vest, aggregate intrinsic value	$ 317
Exercisable (in shares)	2,282,834
Exercisable, weighted average exercise price (in dollars per share)	$ 1.02
Exercisable, weighted average remaining contractual life (Year)	2 years 281 days
Exercisable, aggregate intrinsic value	$ 317