Note 9 - Share Capital (Details Textual)
$ / shares in Units, $ / shares in Units, $ in Thousands, $ in Millions
 12 Months Ended
Nov. 29, 2021
USD ($)
$ / shares
shares
Sep. 08, 2020
USD ($)
$ / shares
shares
Apr. 30, 2020
USD ($)
Apr. 30, 2020
CAD ($)
$ / shares
shares
Jun. 15, 2017
shares
Dec. 31, 2021
USD ($)
$ / shares
shares
Dec. 31, 2021
USD ($)
$ / shares
shares
Dec. 31, 2020
USD ($)
$ / shares
shares
Dec. 31, 2020
USD ($)
$ / shares
shares
Jul. 18, 2020
Dec. 31, 2019
Statement Line Items [Line Items]                      
Number of shares outstanding at end of period (in shares)           97,809,441 97,809,441 94,813,122 94,813,122    
Total number of shares issued (in shares) 2,691,000 3,092,783   4,528,302              
Shares Issued, Price Per Share (in dollars per share) | $ / shares $ 17.15                    
Proceeds from issue of ordinary shares $ 46,151 $ 48,625 $ 43,134 $ 60              
Shares issued, share issue costs, commission | $ 2,301                    
Shares issued, share issue costs, legal and filing | $ 608                    
Proceeds from issue of ordinary shares, net of share issue costs | $ $ 43,242         $ 43,242   $ 89,164      
Issue of equity, price per share (in CAD per share) | $ / shares       $ 13.25              
Issued capital | $   $ 50,000       $ 543,927 $ 543,927 $ 496,604 $ 496,604    
Issue of equity, average price per share (in dollars per share) | $ / shares   $ 16.17                  
Number of share options exercised for cash in share-based payment arrangement           75,066   418,294      
Proceeds from exercise of options | $           $ 985   $ 3,337      
Number of share options exercised in share-based payment arrangement, cashless           54,274   365,483      
Shares issued in lieu of exercise of stock options (in shares)           25,089   139,273      
Number of share options cancelled during the period (in shares)           29,185   226,210      
Shares issued in lieu of payment (in shares)           5,223   8,241      
Mineral property option payment settled by share issuance | $           $ 100   $ 100      
Stock options issuance limitations, maximum percentage of allowed issuable common shares         5.00%            
Option life, share options granted           3   3      
Number of share options outstanding in share-based payment arrangement at end of period           988,727 988,727 1,018,067 1,018,067   1,229,341
Number of share options granted in share-based payment arrangement           100,000   572,503      
Weighted average fair value at measurement date, share options granted | $           $ 686 $ 686 $ 2,546 $ 2,546    
Weighted average share price, share options granted (in dollars per share) | $ / shares           $ 6.86   $ 4.45      
Options vesting, percent, tranche one           0.33%          
Options vesting, period, tranche one (Month)           12 months          
Options vesting, period, tranche two (Month)           24 months          
Options vesting, period, tranche three (Month)           36 months          
Number of share options exercised in share-based payment arrangement           129,340   783,777      
Weighted average market share price of share options exercised In share based payment arrangement (in CAD per share) | $ / shares             $ 22.35   $ 21.79    
Expense from share-based payment transactions with employees and consultants | $           $ 1,564   $ 1,069      
Expense arising from exploration for and evaluation of mineral resources | $           49   15      
Restricted and performance Units issuance limitations, maximum percentage of allowed issuable common shares         1.50%            
Life of restricted share units and performance share units (Year)         5 years            
Number of common shares issuable from a restricted share unit (in shares)         1            
Expense from share-based payment transactions with employees | $           $ 4,256   $ 3,122      
Deferred Units issuance limitations, maximum percentage of allowed issuable common shares                   1.00%  
Number of other equity instruments available for settlement in share-based payment arrangement (in shares)           86,295 86,295        
Common shares issuable under share-based compensation arrangements (in shares)           1,722,974 1,722,974 1,882,225 1,882,225    
Percentage of common shares issuable and common shares issued and outstanding           1.76% 1.76% 1.99% 1.99%    
Number of share based awards available for grant (in shares)           4,145,592 4,145,592 3,806,562 3,806,562    
Options vesting, percent, tranche two               0.33%      
Options vesting, percent, tranche three               0.33%      
Stock options inside of plan [member]                      
Statement Line Items [Line Items]                      
Number of share options outstanding in share-based payment arrangement at end of period           988,727 988,727        
Restricted share units [member]                      
Statement Line Items [Line Items]                      
Number of other equity instruments exercised or vested in share-based payment arrangement           31,620   3,334      
Number of other equity instruments granted in share-based payment arrangement           10,000   39,063      
Weighted average remaining contractual life of other equity instruments granted in share-based payment arrangement (Year)           5 years          
Weighted average exercise price of other equity instruments forfeited in share-based payment arrangement (in dollars per share) | $ / shares           $ 18.44   $ 11.26      
Number of other equity instruments outstanding in share-based payment arrangement at end of period           24,109 24,109 45,729 45,729    
Number of other equity instruments vested and convertible in share-based payment arrangement (in shares)           10,776 10,776 0 0    
Performance share units [member]                      
Statement Line Items [Line Items]                      
Number of other equity instruments exercised or vested in share-based payment arrangement           8,511   17,048      
Number of other equity instruments granted in share-based payment arrangement           0   146,755      
Number of other equity instruments outstanding in share-based payment arrangement at end of period           240,765 240,765 249,276 249,276    
Number of other equity instruments vested and convertible in share-based payment arrangement (in shares)           6,346 6,346 14,857 14,857    
Number of other equity instruments outstanding with vesting conditions subject to a market share price performance factor (in shares)           87,664 87,664 87,664 87,664    
Number of other equity instruments exercisable in share-based payment arrangement           48,918 48,918        
Deferred share units [member]                      
Statement Line Items [Line Items]                      
Number of other equity instruments exercised or vested in share-based payment arrangement           159,810   60,000      
Number of other equity instruments granted in share-based payment arrangement           54,213   64,757      
Number of other equity instruments outstanding in share-based payment arrangement at end of period           469,373 469,373 569,153 569,153    
Expense from share-based payment transactions with employees | $           $ 1,208   $ 867      
Number of instruments other equity instruments granted in lieu of director fees (in shares)           5,818   10,482      
Number of common shares issued under the deferred share unit plan prior to termination date (in shares)           0 0        
Stock option awards [member]                      
Statement Line Items [Line Items]                      
Option life, share options granted           5          
Restricted share units and performance share units [member]                      
Statement Line Items [Line Items]                      
Expense from share-based payment transactions with employees | $           $ 1,533   $ 1,201      
Top of range [member]                      
Statement Line Items [Line Items]                      
Issue of equity, at-the-market equity program, shares authorized (in shares)   50,000,000                  
Option life, share options granted         5            
Performance share unit payout, percentage           200.00%          
Performance share unit payout, units (in shares)           175,328          
Top of range [member] | Performance share units [member]                      
Statement Line Items [Line Items]                      
Performance share unit payout, percentage           150.00%          
Performance share unit payout, units (in shares)           73,377          
Bottom of range [member]                      
Statement Line Items [Line Items]                      
Performance share unit payout, percentage           0.00%          
Performance share unit payout, units (in shares)           0          
Bottom of range [member] | Performance share units [member]                      
Statement Line Items [Line Items]                      
Performance share unit payout, percentage           50.00%          
Performance share unit payout, units (in shares)           24,459