Note 1 - Summary of Significant Accounting Policies - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
	Mar. 31, 2020	Jun. 30, 2020
Outstanding (in shares)	372,200	372,200
Outstanding, weighted average exercise price per share (in dollars per share)	$ 3.85	$ 3.85
Granted (in shares)	11,300	11,300
Granted, weighted average exercise price per share (in dollars per share)		$ 2.95
Cancelled (in shares)		(4,000)
Cancelled, weighted average exercise price per share (in dollars per share)		$ 3.29
Outstanding (in shares)		379,500
Outstanding, weighted average exercise price per share (in dollars per share)		$ 3.83
Outstanding, weighted average remaining contractual term (Year)		8 years 47 days
Outstanding, aggregate intrinsic value		$ 218
Exercisable (in shares)		182,240
Exercisable, weighted average exercise price per share (in dollars per share)		$ 3.72
Exercisable, weighted average remaining contractual term (Year)		7 years 255 days
Exercisable, aggregate intrinsic value		$ 119