<?xml version="1.0" encoding="utf-8"?>
<xbrl
  xmlns="http://www.xbrl.org/2003/instance"
  xmlns:cik0000086521="http://San.com/20200928"
  xmlns:dei="http://xbrl.sec.gov/dei/2019-01-31"
  xmlns:link="http://www.xbrl.org/2003/linkbase"
  xmlns:us-gaap="http://fasb.org/us-gaap/2019-01-31"
  xmlns:xbrldi="http://xbrl.org/2006/xbrldi"
  xmlns:xlink="http://www.w3.org/1999/xlink">
    <link:schemaRef xlink:href="cik0000086521-20200928.xsd" xlink:type="simple"/>
    <context id="P09_28_2020To09_28_2020">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000086521</identifier>
        </entity>
        <period>
            <startDate>2020-09-28</startDate>
            <endDate>2020-09-28</endDate>
        </period>
    </context>
    <context id="P09_28_2020To09_28_2020_SempraEnergyMemberusgaapStatementClassOfStockAxis">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000086521</identifier>
            <segment>
                <xbrldi:explicitMember dimension="us-gaap:StatementClassOfStockAxis">cik0000086521:SempraEnergyMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-09-28</startDate>
            <endDate>2020-09-28</endDate>
        </period>
    </context>
    <context id="P09_28_2020To09_28_2020_SempraEnergyCommonStockWithoutParValueMemberdeiLegalEntityAxis">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000086521</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">cik0000086521:SempraEnergyCommonStockWithoutParValueMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-09-28</startDate>
            <endDate>2020-09-28</endDate>
        </period>
    </context>
    <context id="P09_28_2020To09_28_2020_SempraEnergy6MandatoryConvertiblePreferredStockSeriesA100LiquidationPreferenceMemberdeiLegalEntityAxis">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000086521</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">cik0000086521:SempraEnergy6MandatoryConvertiblePreferredStockSeriesA100LiquidationPreferenceMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-09-28</startDate>
            <endDate>2020-09-28</endDate>
        </period>
    </context>
    <context id="P09_28_2020To09_28_2020_SempraEnergy675MandatoryConvertiblePreferredStockSeriesB100LiquidationPreferenceMemberdeiLegalEntityAxis">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000086521</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">cik0000086521:SempraEnergy675MandatoryConvertiblePreferredStockSeriesB100LiquidationPreferenceMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-09-28</startDate>
            <endDate>2020-09-28</endDate>
        </period>
    </context>
    <context id="P09_28_2020To09_28_2020_SempraEnergy575JuniorSubordinatedNotesDue202925ParValueMemberdeiLegalEntityAxis">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000086521</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">cik0000086521:SempraEnergy575JuniorSubordinatedNotesDue202925ParValueMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-09-28</startDate>
            <endDate>2020-09-28</endDate>
        </period>
    </context>
    <dei:AmendmentFlag contextRef="P09_28_2020To09_28_2020">false</dei:AmendmentFlag>
    <dei:EntityCentralIndexKey contextRef="P09_28_2020To09_28_2020">0000086521</dei:EntityCentralIndexKey>
    <dei:EntityAddressStateOrProvince
      contextRef="P09_28_2020To09_28_2020_SempraEnergyMemberusgaapStatementClassOfStockAxis"
      id="hidden14984909">CA</dei:EntityAddressStateOrProvince>
    <dei:EntityAddressStateOrProvince contextRef="P09_28_2020To09_28_2020" id="hidden14984910">CA</dei:EntityAddressStateOrProvince>
    <dei:DocumentType contextRef="P09_28_2020To09_28_2020">8-K</dei:DocumentType>
    <dei:DocumentPeriodEndDate contextRef="P09_28_2020To09_28_2020">2020-09-28</dei:DocumentPeriodEndDate>
    <dei:EntityFileNumber contextRef="P09_28_2020To09_28_2020_SempraEnergyMemberusgaapStatementClassOfStockAxis">1-14201</dei:EntityFileNumber>
    <dei:EntityRegistrantName contextRef="P09_28_2020To09_28_2020_SempraEnergyMemberusgaapStatementClassOfStockAxis">SEMPRA ENERGY</dei:EntityRegistrantName>
    <dei:EntityAddressAddressLine1 contextRef="P09_28_2020To09_28_2020_SempraEnergyMemberusgaapStatementClassOfStockAxis">488 8th Avenue</dei:EntityAddressAddressLine1>
    <dei:EntityAddressCityOrTown contextRef="P09_28_2020To09_28_2020_SempraEnergyMemberusgaapStatementClassOfStockAxis">San Diego</dei:EntityAddressCityOrTown>
    <dei:EntityAddressPostalZipCode contextRef="P09_28_2020To09_28_2020_SempraEnergyMemberusgaapStatementClassOfStockAxis">92101</dei:EntityAddressPostalZipCode>
    <dei:CityAreaCode contextRef="P09_28_2020To09_28_2020_SempraEnergyMemberusgaapStatementClassOfStockAxis">619</dei:CityAreaCode>
    <dei:LocalPhoneNumber contextRef="P09_28_2020To09_28_2020_SempraEnergyMemberusgaapStatementClassOfStockAxis">696-2000</dei:LocalPhoneNumber>
    <dei:EntityIncorporationStateCountryCode contextRef="P09_28_2020To09_28_2020_SempraEnergyMemberusgaapStatementClassOfStockAxis">CA</dei:EntityIncorporationStateCountryCode>
    <dei:EntityTaxIdentificationNumber contextRef="P09_28_2020To09_28_2020_SempraEnergyMemberusgaapStatementClassOfStockAxis">33-0732627</dei:EntityTaxIdentificationNumber>
    <dei:EntityFileNumber contextRef="P09_28_2020To09_28_2020">1-03779</dei:EntityFileNumber>
    <dei:EntityRegistrantName contextRef="P09_28_2020To09_28_2020">SAN DIEGO GAS &amp; ELECTRIC CO</dei:EntityRegistrantName>
    <dei:EntityAddressAddressLine1 contextRef="P09_28_2020To09_28_2020">8326 Century Park Court</dei:EntityAddressAddressLine1>
    <dei:EntityAddressCityOrTown contextRef="P09_28_2020To09_28_2020">San Diego</dei:EntityAddressCityOrTown>
    <dei:EntityAddressPostalZipCode contextRef="P09_28_2020To09_28_2020">92123</dei:EntityAddressPostalZipCode>
    <dei:CityAreaCode contextRef="P09_28_2020To09_28_2020">619</dei:CityAreaCode>
    <dei:LocalPhoneNumber contextRef="P09_28_2020To09_28_2020">696-2000</dei:LocalPhoneNumber>
    <dei:EntityIncorporationStateCountryCode contextRef="P09_28_2020To09_28_2020">CA</dei:EntityIncorporationStateCountryCode>
    <dei:EntityTaxIdentificationNumber contextRef="P09_28_2020To09_28_2020">95-1184800</dei:EntityTaxIdentificationNumber>
    <dei:WrittenCommunications contextRef="P09_28_2020To09_28_2020">false</dei:WrittenCommunications>
    <dei:SolicitingMaterial contextRef="P09_28_2020To09_28_2020">false</dei:SolicitingMaterial>
    <dei:PreCommencementTenderOffer contextRef="P09_28_2020To09_28_2020">false</dei:PreCommencementTenderOffer>
    <dei:PreCommencementIssuerTenderOffer contextRef="P09_28_2020To09_28_2020">false</dei:PreCommencementIssuerTenderOffer>
    <dei:Security12bTitle contextRef="P09_28_2020To09_28_2020_SempraEnergyCommonStockWithoutParValueMemberdeiLegalEntityAxis">Sempra Energy Common Stock, without par value</dei:Security12bTitle>
    <dei:TradingSymbol contextRef="P09_28_2020To09_28_2020_SempraEnergyCommonStockWithoutParValueMemberdeiLegalEntityAxis">SRE</dei:TradingSymbol>
    <dei:SecurityExchangeName contextRef="P09_28_2020To09_28_2020_SempraEnergyCommonStockWithoutParValueMemberdeiLegalEntityAxis">NYSE</dei:SecurityExchangeName>
    <dei:Security12bTitle contextRef="P09_28_2020To09_28_2020_SempraEnergy6MandatoryConvertiblePreferredStockSeriesA100LiquidationPreferenceMemberdeiLegalEntityAxis">Sempra Energy 6% Mandatory Convertible Preferred Stock, Series A, $100 liquidation preference</dei:Security12bTitle>
    <dei:TradingSymbol contextRef="P09_28_2020To09_28_2020_SempraEnergy6MandatoryConvertiblePreferredStockSeriesA100LiquidationPreferenceMemberdeiLegalEntityAxis">SREPRA</dei:TradingSymbol>
    <dei:SecurityExchangeName contextRef="P09_28_2020To09_28_2020_SempraEnergy6MandatoryConvertiblePreferredStockSeriesA100LiquidationPreferenceMemberdeiLegalEntityAxis">NYSE</dei:SecurityExchangeName>
    <dei:Security12bTitle contextRef="P09_28_2020To09_28_2020_SempraEnergy675MandatoryConvertiblePreferredStockSeriesB100LiquidationPreferenceMemberdeiLegalEntityAxis">Sempra Energy 6.75% Mandatory Convertible Preferred Stock, Series B, $100 liquidation preference</dei:Security12bTitle>
    <dei:TradingSymbol contextRef="P09_28_2020To09_28_2020_SempraEnergy675MandatoryConvertiblePreferredStockSeriesB100LiquidationPreferenceMemberdeiLegalEntityAxis">SREPRB</dei:TradingSymbol>
    <dei:SecurityExchangeName contextRef="P09_28_2020To09_28_2020_SempraEnergy675MandatoryConvertiblePreferredStockSeriesB100LiquidationPreferenceMemberdeiLegalEntityAxis">NYSE</dei:SecurityExchangeName>
    <dei:Security12bTitle contextRef="P09_28_2020To09_28_2020_SempraEnergy575JuniorSubordinatedNotesDue202925ParValueMemberdeiLegalEntityAxis">Sempra Energy 5.75% Junior Subordinated Notes Due 2029, $25 par value</dei:Security12bTitle>
    <dei:TradingSymbol contextRef="P09_28_2020To09_28_2020_SempraEnergy575JuniorSubordinatedNotesDue202925ParValueMemberdeiLegalEntityAxis">SREA</dei:TradingSymbol>
    <dei:SecurityExchangeName contextRef="P09_28_2020To09_28_2020_SempraEnergy575JuniorSubordinatedNotesDue202925ParValueMemberdeiLegalEntityAxis">NYSE</dei:SecurityExchangeName>
    <dei:EntityEmergingGrowthCompany contextRef="P09_28_2020To09_28_2020_SempraEnergyMemberusgaapStatementClassOfStockAxis">false</dei:EntityEmergingGrowthCompany>
    <dei:EntityEmergingGrowthCompany contextRef="P09_28_2020To09_28_2020">false</dei:EntityEmergingGrowthCompany>
</xbrl>
