SAN ONOFRE NUCLEAR GENERATING STATION - NUCLEAR INSURANCE (Details) - San Diego Gas and Electric Company [Member] $ in Millions	Sep. 30, 2019 USD ($)
Schedule Of Nuclear Insurance [Line Items]
Maximum nuclear liability insurance coverage	$ 450.0
Maximum secondary financial protection	110.0
Maximum nuclear liability loss coverage per incident	560.0
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