XML 142 R135.htm IDEA: XBRL DOCUMENT v3.8.0.1
Intangible assets (Details 2)
 12 Months Ended
Dec. 31, 2017
Intangible Exploration And Evaluation Assets [Member]  
DisclosureOfIntangibleAssetsExplanatoryLineItems [Line Items]  
Useful lives or amortisation rates intangible assets other than goodwill UOP - 33
Transport rights of natural gas [Member]  
DisclosureOfIntangibleAssetsExplanatoryLineItems [Line Items]  
Useful lives or amortisation rates intangible assets other than goodwill 3
Other concessions, licenses, trademarks and similar items [Member]  
DisclosureOfIntangibleAssetsExplanatoryLineItems [Line Items]  
Useful lives or amortisation rates intangible assets other than goodwill 3 - 33
Service concession arrangement [Member]  
DisclosureOfIntangibleAssetsExplanatoryLineItems [Line Items]  
Useful lives or amortisation rates intangible assets other than goodwill 20 - 33
Other Intangible Assets [Member]  
DisclosureOfIntangibleAssetsExplanatoryLineItems [Line Items]  
Useful lives or amortisation rates intangible assets other than goodwill 4 - 20