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Environment (Details Textual)
 12 Months Ended
Dec. 31, 2017
Industrial waste water treatment [Member]  
Disclosure of Environment [Line Items]  
Percentage of distribution of environmental costs 50.80%
Solid industrial residues [Member]  
Disclosure of Environment [Line Items]  
Percentage of distribution of environmental costs 36.40%
Gas emission expenses [Member]  
Disclosure of Environment [Line Items]  
Percentage of distribution of environmental costs 0.70%
Other environmental expenses [Member]  
Disclosure of Environment [Line Items]  
Percentage of distribution of environmental costs 12.10%