Note 8 - Stock-based Compensation - Stock Option Activity (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021 USD ($) $ / shares shares
Outstanding, number of options (in shares) | shares	484,500
Outstanding, option, weighted average exercise price (in dollars per share) | $ / shares	$ 3.57
Granted, options (in shares) | shares
Grantedg, option, weighted average exercise price (in dollars per share) | $ / shares
Exercised, options (in shares) | shares
Exercisedg, option, weighted average exercise price (in dollars per share) | $ / shares
Expired or forfeited, options (in shares) | shares
Expired or forfeitedg, option, weighted average exercise price (in dollars per share) | $ / shares
Outstanding, number of options (in shares) | shares	484,500
Outstandingg, option, weighted average exercise price (in dollars per share) | $ / shares	$ 3.57
Outstanding, weighted average remaining contractual term (Year)	3 years 167 days
Outstanding, aggregate intrinsic value | $	$ 307,020
Exercisable, options (in shares) | shares	484,500
Exercisableg, option, weighted average exercise price (in dollars per share) | $ / shares	$ 3.57
Exercisable, weighted average remaining contractual term (Year)	3 years 167 days
Exercisable, aggregate intrinsic value | $	$ 307,020