| The amount of regulatory deferral account credit balances and the related deferred tax liability. [Refer: Regulatory deferral account credit balances; Deferred tax liability associated with regulatory deferral account balances] | en | http://www.xbrl.org/2003/role/documentation | http://www.xbrl.org/2003/role/link |
| Regulatory deferral account credit balances and related deferred tax liability | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Total regulatory deferral account credit balances and related deferred tax liability | en | http://www.xbrl.org/2003/role/totalLabel | http://www.xbrl.org/2003/role/link |