| Contingent liabilities [member] | |||||||||
| Legal proceedings contingent liability [member] | Onerous contracts contingent liability [member] | Contingent liability for decommissioning, restoration and rehabilitation costs [member] | Other environment related contingent liability [member] | Tax contingent liability [member] | Contingent liability arising from post-employment benefit obligations [member] | Other contingent liabilities [member] | |||
| Disclosure of contingent liabilities [line items] | |||||||||
| Description of nature of obligation, contingent liabilities | |||||||||
| Explanation of estimated financial effect of contingent liabilities | |||||||||
| Efecto financiero esperado de pasivos contingentes | |||||||||
| Explanation of possibility of reimbursement, contingent liabilities | |||||||||
| Indication of uncertainties of amount or timing of outflows, contingent liabilities | |||||||||