Note 9 - Incentive Plans - Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended		24 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020
Outstanding (in shares)	372,200	224,750	224,750
Outstanding, weighted average exercise price (in dollars per share)	$ 3.85	$ 3.44	$ 3.44
Granted (in shares)	42,300	186,200
Granted, weighted average exercise price (in dollars per share)	$ 4.34	$ 4.31
Exercised (in shares)	(14,133)	(2,250)
Exercised, weighted average exercise price (in dollars per share)	$ (3.78)		$ (3.20)
Cancelled (in shares)	(37,727)	(36,500)
Cancelled, weighted average exercise price (in dollars per share)	$ (3.37)	$ (3.66)
Outstanding, weighted average remaining contractual term (Year)	7 years 284 days	8 years 208 days
Outstanding, aggregate intrinsic value	$ 1,164	$ 379	$ 1,164
Outstanding (in shares)	362,640	372,200	362,640
Outstanding, weighted average exercise price (in dollars per share)	$ 3.96	$ 3.85	$ 3.96
Exercisable (in shares)	150,840		150,840
Exercisable, weighted average exercise price (in dollars per share)	$ 3.61		$ 3.61
Exercisable, weighted average remaining contractual term (Year)	7 years 32 days
Exercisable, aggregate intrinsic value	$ 537		$ 537