Note 5 - Share-based Compensation - Stock Options Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Options outstanding (in shares)	222,000	624,000
Options outstanding, weighted exercise price (in dollars per share)	$ 0.19	$ 0.39
Options outstanding, weighted life (Year)	193 days	1 year 229 days	1 year 233 days
Granted (in shares)
Granted, weighted exercise price (in dollars per share)
Exercised (in shares)	(7,000)	(67,000)
Exercised, weighted exercise price (in dollars per share)	$ 0.05	$ 0.05
Forfeited/Cancelled (in shares)		(335,000)
Forfeite/Cancelled, weighted exercise price (in dollars per share)		$ 0.55
Options outstanding (in shares)	215,000	222,000	624,000
Options outstanding, weighted exercise price (in dollars per share)	$ 0.20	$ 0.19	$ 0.39
Options exercisable (in shares)	215,000	215,000
Options exercisable, weighted exercise price (in dollars per share)	$ 0.20	$ 0.20
Options exercisable, weighted life (Year)	193 days	1 year 229 days