Note 8 - Incentive Plans - Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Outstanding (in shares)	224,750	187,750
Outstanding, weighted average exercise price (in dollars per share)	$ 3.44	$ 3.70
Granted (in shares)	186,200	134,000
Granted, weighted average exercise price (in dollars per share)	$ 4.31	$ 3.36
Exercised (in shares)	(2,250)	0
Exercised, weighted average exercise price (in dollars per share)	$ 3.20
Cancelled (in shares)	(36,500)	(97,000)
Cancelled, weighted average exercise price (in dollars per share)	$ (3.66)	$ (3.84)
Outstanding, weighted average remaining contractual term (Year)	8 years 208 days	8 years 219 days
Outstanding, aggregate intrinsic value	$ 379,429	$ 52,715
Exercised, weighted average exercise price (in dollars per share)	$ (3.20)
Outstanding (in shares)	372,200	224,750
Outstanding, weighted average exercise price (in dollars per share)	$ 3.85	$ 3.44
Exercisable (in shares)	107,567
Exercisable, weighted average exercise price (in dollars per share)	$ 3.44
Exercisable, weighted average remaining contractual term (Year)	7 years 251 days
Exercisable, aggregate intrinsic value	$ 154,305