Note 10 - Stock Options and Warrants - Nonvested Option Awards Activity (Details)	12 Months Ended
	Dec. 31, 2019 $ / shares shares
Nonvested, Shares, Balance (in shares) | shares	148,500
Nonvested, weighted average grant date fair value (in dollars per share) | $ / shares	$ 0.20
Options granted, shares (in shares) | shares	3,000
Granted, weighted average grant date fair value (in dollars per share) | $ / shares	$ 0.11
Vested, shares (in shares) | shares	(123,000)
Vested, weighted average grant date fair value (in dollars per share) | $ / shares	$ 0.20
Forfeited, shares (in shares) | shares	(5,000)
Forfeited, weighted average grant date fair value (in dollars per share) | $ / shares	$ 0.21
Nonvested, shares (in shares) | shares	23,500
Nonvested, weighted average grant date fair value (in dollars per share) | $ / shares	$ 0.17