Note 12 - Share-based Compensation - Summary of RSU Activity (Details) - $ / shares
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Restricted Stock Units (RSUs) [Member]      
Awards other than options, unvested, beginning balance (in shares) 428,006 308,087  
Awards other than options, unvested, weighted average grant date fair value, beginning balance (in dollars per share) $ 6.13 $ 6.77  
Unvested, vesting period (Year) 2 years 2 years 3 months 18 days 3 years
Awards other than options, Vested (in shares) (524,491) (144,687)  
Awards other than options, vested, weighted average grant date fair value (in dollars per share) $ 5.55 $ 5.17  
Awards other than options, Forfeited and cancelled (in shares) (32,874) (81,479)  
Awards other than options, forfeited and cancelled, weighted average grant date fair value (in dollars per share) $ 6.10 $ 6.47  
Awards other than options, unvested, ending balance (in shares) 269,303 428,006 308,087
Awards other than options, unvested, weighted average grant date fair value, ending balance (in dollars per share) $ 6.47 $ 6.13 $ 6.77
Service-based RSU [Member]      
Awards other than options, Granted (in shares) 398,662 310,874  
Awards other than options, granted, weighted average grant date fair value (in dollars per share) $ 5.59 $ 6.02  
Performance-based RSU [Member]      
Awards other than options, Granted (in shares)   35,211  
Awards other than options, granted, weighted average grant date fair value (in dollars per share)   $ 4.26