Note 13 - Share-based Compensation - Stock Option Activity (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) $ / shares shares
Options outstanding (in shares) | shares	257,400
Options outstanding, weighted average exercise price (in dollars per share) | $ / shares	$ 22.61
Issued (in shares) | shares	121,250
Issued, weighted average exercise price (in dollars per share) | $ / shares	$ 32.32
Exercised (in shares) | shares	(47,700)
Exercised, weighted average exercise price (in dollars per share) | $ / shares	$ 17.29
Forfeited or expired (in shares) | shares	(2,950)
Forfeited or expired, weighted average exercise price (in dollars per share) | $ / shares	$ 26.84
Options outstanding (in shares) | shares	328,000
Options outstanding, weighted average exercise price (in dollars per share) | $ / shares	$ 26.94
Options outstanding, weighted average remaining term (Year)	5 years 7 months 6 days
Options outstanding, intrinsic value | $	$ 1,510,216
Expected to vest (in shares) | shares	153,700
Expected to vest, weighted average exercise price (in dollars per share) | $ / shares	$ 29.62
Expected to vest, weighted average remaining term (Year)	6 years 10 months 24 days
Expected to vest, intrinsic value | $	$ 580,937
Exercisable (in shares) | shares	174,300
Exercisable, weighted average exercise price (in dollars per share) | $ / shares	$ 24.57
Exercisable, weighted average remaining term (Year)	3 years 9 months 18 days
Exercisable, intrinsic value | $	$ 929,279