Note 10 - Incentive Plans - Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Outstanding (in shares)	362,640	372,200
Outstanding, weighted average exercise price (in dollars per share)	$ 3.96	$ 3.85
Granted (in shares)	49,000	42,300
Granted, weighted average exercise price (in dollars per share)	$ 8.50	$ 4.34
Exercised (in shares)	(13,400)	(14,133)
Exercised, weighted average exercise price (in dollars per share)	$ 3.43	$ 3.78
Cancelled (in shares)	(10,740)	(37,727)
Cancelled, weighted average exercise price (in dollars per share)	$ 3.42	$ 3.37
Outstanding, weighted average remaining contractual term (Year)	7 years 2 months 1 day	7 years 9 months 10 days
Outstanding, aggregate intrinsic value	$ 2,250	$ 1,164
Outstanding (in shares)	387,500	362,640
Outstanding, weighted average exercise price (in dollars per share)	$ 4.57	$ 3.96
Exercisable (in shares)	186,700
Exercisable, weighted average exercise price (in dollars per share)	$ 3.79
Exercisable, weighted average remaining contractual term (Year)	6 years 3 months 21 days
Exercisable, aggregate intrinsic value	$ 1,225