| Cover | Aug. 05, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Aug. 5, 2021 |
| Entity Registrant Name | SAN DIEGO GAS & ELECTRIC COMPANY |
| Entity Incorporation, State or Country Code | CA |
| Entity File Number | 1-03779 |
| Entity Tax Identification Number | 95-1184800 |
| Entity Address, Address Line One | 8326 Century Park Court |
| Entity Address, City or Town | San Diego |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 92123 |
| City Area Code | (619) |
| Local Phone Number | 696-2000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0000086521 |
| Amendment Flag | false |
