| Contingent liability for decommissioning, restoration and rehabilitation costs [member] | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| This member stands for a contingent liability relating to decommissioning, restoration and rehabilitation costs. [Refer: Contingent liabilities [member]] | en | http://www.xbrl.org/2003/role/documentation | http://www.xbrl.org/2003/role/link |
| Passivo contingente para custos de descomissionamento, restauro e reabilitação [member] | pt | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Este membro representa um passivo contingente relacionado com os custos de descomissionamento, restauro e reabilitação. [Consultar: Passivos contingentes [member]] | pt | http://www.xbrl.org/2003/role/documentation | http://www.xbrl.org/2003/role/link |