SAN ONOFRE NUCLEAR GENERATING STATION - NUCLEAR INSURANCE (Details) - San Diego Gas and Electric Company [Member] $ in Millions	Dec. 31, 2019 USD ($)
Public Utilities, General Disclosures [Line Items]
Maximum required nuclear liability insurance available	$ 450.0
Maximum secondary financial protection available	110.0
Maximum nuclear liability loss coverage per incident	560.0
Federal Nuclear Property Damage Insurance	1,500.0
Spent Nuclear Fuel Storage Insurance	500.0
Federal nuclear property damage insurance, minimum required	1,060.0
Maximum premium assessment under nuclear property damage insurance	10.4
Maximum nuclear property insurance terrorism coverage	$ 3,240.0