Note 8 - Stockholders' Equity - Options Outstanding by Exercise Price (Details)	3 Months Ended
	Mar. 31, 2019 $ / shares shares
Options outstanding (in shares) | shares	25,000
Options outstanding, weighted average remaining contractual life (Year)	1 year 135 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 2.96
Options exercisable (in shares) | shares	25,000
Options exercisable, weighted average exercise price (in dollars per share)	$ 2.96
Price Range 1 [Member]
Exercise prices of options (in dollars per share)	$ 2.96
Options outstanding (in shares) | shares	25,000
Options outstanding, weighted average remaining contractual life (Year)	1 year 135 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 2.96
Options exercisable (in shares) | shares	25,000
Options exercisable, weighted average exercise price (in dollars per share)	$ 2.96