| Decrease through balances recovered in current period, regulatory deferral account debit balances | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Decrease through balances recovered in current period, regulatory deferral account debit balances | en | http://www.xbrl.org/2009/role/negatedLabel | http://www.xbrl.org/2003/role/link |
| The decrease in regulatory deferral account debit balances resulting from balances recovered in the current period. [Refer: Regulatory deferral account debit balances] | en | http://www.xbrl.org/2003/role/documentation | http://www.xbrl.org/2003/role/link |
| Diminuzione per saldi recuperati nell'esercizio corrente, saldi a debito dei regulatory deferral account | it | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| La diminuzione dei saldi a debito dei regulatory deferral account dovuta ai saldi recuperati nell'esercizio corrente. [Rif: Saldi a debito dei regulatory deferral account] | it | http://www.xbrl.org/2003/role/documentation | http://www.xbrl.org/2003/role/link |
| Diminuzione per saldi recuperati nell'esercizio corrente, saldi a debito dei regulatory deferral account | it | http://www.xbrl.org/2009/role/negatedLabel | http://www.xbrl.org/2003/role/link |