| Other comprehensive income, net of tax, net movement in regulatory deferral account balances related to items that will be reclassified to profit or loss | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Other comprehensive income, net of tax, net movement in regulatory deferral account balances related to items that will be reclassified to profit or loss | en | http://www.xbrl.org/2003/role/totalLabel | http://www.xbrl.org/2003/role/link |
| The amount of other comprehensive income, net of tax, related to the net movement in regulatory deferral account balances that is related to items that will be reclassified to profit or loss. [Refer: Regulatory deferral account balances [member]; Other comprehensive income] | en | http://www.xbrl.org/2003/role/documentation | http://www.xbrl.org/2003/role/link |
| Outro rendimento integral, líquido de impostos, movimento líquido nos saldos dos diferimentos regulamentares relacionado com os itens a serem reclassificados nos resultados | pt | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| A quantia de outro rendimento integral, líquido de impostos, relativo ao movimento líquido nos saldos dos diferimentos regulamentares relacionado com os itens a serem reclassificados nos resultados. [Consultar: Saldos dos diferimentos regulamentares [member]; Outro rendimento integral] | pt | http://www.xbrl.org/2003/role/documentation | http://www.xbrl.org/2003/role/link |
| Outro rendimento integral, líquido de impostos, movimento líquido nos saldos dos diferimentos regulamentares relacionado com os itens a serem reclassificados nos resultados | pt | http://www.xbrl.org/2003/role/totalLabel | http://www.xbrl.org/2003/role/link |