XML 103 R71.htm IDEA: XBRL DOCUMENT v3.8.0.1
Financial Instruments - Fair Value Hierarchy (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Disclosure of Financial Assets and Liabilities [Line Items]    
Short-term investments (Note 8) $ 51,590 $ 36,729
Current derivative financial liabilities (1,906) (2,815)
Financial assets 102,728 78,874
Level 1 [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Financial assets 51,590 36,729
Level 2 [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Financial assets 51,138 42,145
Level 3 [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Financial assets 0 0
Warrants [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Financial assets 1,092  
Warrants [member] | Level 1 [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Financial assets 0  
Warrants [member] | Level 2 [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Financial assets 1,092  
Warrants [member] | Level 3 [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Financial assets 0  
Zinc contracts [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Current derivative financial liabilities (716) (1,769)
Zinc contracts [member] | Level 1 [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Current derivative financial liabilities 0 0
Zinc contracts [member] | Level 2 [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Current derivative financial liabilities (716) (1,769)
Zinc contracts [member] | Level 3 [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Current derivative financial liabilities 0 0
Lead contracts [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Current derivative financial liabilities (243) (54)
Lead contracts [member] | Level 1 [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Current derivative financial liabilities 0  
Lead contracts [member] | Level 2 [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Current derivative financial liabilities (243) (54)
Lead contracts [member] | Level 3 [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Current derivative financial liabilities 0  
Copper contracts [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Current derivative financial liabilities (891)  
Copper contracts [member] | Level 1 [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Current derivative financial liabilities 0  
Copper contracts [member] | Level 2 [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Current derivative financial liabilities (891)  
Copper contracts [member] | Level 3 [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Current derivative financial liabilities 0  
Currency swap contract [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Current derivative financial liabilities (56) (992)
Currency swap contract [member] | Level 1 [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Current derivative financial liabilities 0 0
Currency swap contract [member] | Level 2 [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Current derivative financial liabilities (56) (992)
Currency swap contract [member] | Level 3 [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Current derivative financial liabilities 0 0
Short-term investments [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Short-term investments (Note 8) 51,590 36,729
Short-term investments [member] | Level 1 [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Short-term investments (Note 8) 51,590 36,729
Short-term investments [member] | Level 2 [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Short-term investments (Note 8) 0 0
Short-term investments [member] | Level 3 [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Short-term investments (Note 8) 0 0
Trade receivables from provisional concentrate sales [member] | Trade and other receivables    
Disclosure of Financial Assets and Liabilities [Line Items]    
Financial assets 51,952 44,960
Trade receivables from provisional concentrate sales [member] | Trade and other receivables | Level 1 [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Financial assets 0 0
Trade receivables from provisional concentrate sales [member] | Trade and other receivables | Level 2 [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Financial assets 51,952 44,960
Trade receivables from provisional concentrate sales [member] | Trade and other receivables | Level 3 [member]    
Disclosure of Financial Assets and Liabilities [Line Items]    
Financial assets $ 0 $ 0