Note 10 - Share Based Payments - Non-vested Stock Options (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Non-vested stock options, shares (in shares)	1,138,500	2,137,000
Non-vested stock options, Weighted average fair value (in dollars per share)	$ 0.20	$ 0.13
Options granted, shares (in shares)	250,000	250,000
Options granted, Weighted average fair value (in dollars per share)	$ 0.80	$ 0.47
Vested during period, shares (in shares)	(971,833)	(1,231,000)
Vested during period, Weighted average fair value (in dollars per share)	$ (0.16)	$ (0.13)
Options cancelled, shares (in shares)		(17,500)
Options cancelled, Weighted average fair value (in dollars per share)		$ (0.13)
Non-vested shares under option, shares (in shares)	416,667	1,138,500
Non-vested shares under option, Weighted average fair value (in dollars per share)	$ 0.67	$ 0.20