Note 9 - Stockholders' Equity - Stock Option Activity (Details)	3 Months Ended
	Mar. 31, 2020 $ / shares shares
Outstanding, number of options, balance (in shares) | shares	3,200,750
Outstanding, weighted average exercise price, balance (in dollars per share) | $ / shares	$ 0.45
Granted, number of options (in shares) | shares	0
Granted, weighted average exercise price (in dollars per share) | $ / shares
Exercised, number of options (in shares) | shares	0
Exercised, weighted average exercise price (in dollars per share) | $ / shares
Cancelled, number of options (in shares) | shares	(70,000)
Cancelled, weighted average exercise price (in dollars per share) | $ / shares	$ (0.42)
Outstanding, number of options, balance (in shares) | shares	3,130,750
Outstanding, weighted average exercise price, balance (in dollars per share) | $ / shares	$ 0.45