Note 10 - Share-based Compensation - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Options on Common Shares, Outstanding (in shares)	3,935,883
Outstanding, weighted average exercise price (in dollars per share)	$ 5.24
Outstanding, remaining contractual term (Year)	3 years 6 months 29 days	4 years 9 months 14 days
Options on Common Shares, Granted (in shares)	104,000
Granted, weighted average exercise price (in dollars per share)	$ 3.55
Options on Common Shares, Exercised (in shares)	(50,000)
Exercised, weighted average exercise price (in dollars per share)	$ 1.50
Options on Common Shares, Forfeited, cancelled, expired (in shares)	(388,912)
Forfeited, cancelled, expired, weighted average exercise price (in dollars per share)	$ 5.01
Options on Common Shares, Outstanding (in shares)	3,600,971	3,935,883
Outstanding, weighted average exercise price (in dollars per share)	$ 5.27	$ 5.24
Outstanding March 31, 2022	$ 774
Exercisable March 31, 2022 (in shares)	2,549,388
Exercisable weighted average exercise price (in dollars per share)	$ 2.86
Exercisable, remaining contractual term (Year)	2 years 10 days
Exercisable March 31, 2022	$ 761