| The decrease in regulatory deferral account credit balances resulting from disposals. [Refer: Regulatory deferral account credit balances] | en | http://www.xbrl.org/2003/role/documentation | http://www.xbrl.org/2003/role/link |
| Decrease through disposals, regulatory deferral account credit balances | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Decrease through disposals, regulatory deferral account credit balances | en | http://www.xbrl.org/2009/role/negatedLabel | http://www.xbrl.org/2003/role/link |