Investments (Amortized Cost and Fair Value of Nuclear Decommissioning Trusts) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Nuclear Decommissioning Trusts Disclosures
Fair Value	$ 4,566	$ 4,562
Southern California Edison
Nuclear Decommissioning Trusts Disclosures
Amortized Cost	2,426	2,447
Fair Value	4,566	4,562
Southern California Edison | Municipal bonds
Nuclear Decommissioning Trusts Disclosures
Amortized Cost	1,013	822
Southern California Edison | U.S. government and agency securities
Nuclear Decommissioning Trusts Disclosures
Amortized Cost	703	996
Southern California Edison | Corporate bonds
Nuclear Decommissioning Trusts Disclosures
Amortized Cost	542	597
Southern California Edison | Short-term investments and receivables/payables
Nuclear Decommissioning Trusts Disclosures
Amortized Cost	168	32
Southern California Edison | Fair Value, Measurements, Recurring
Nuclear Decommissioning Trusts Disclosures
Fair Value	4,706	4,673
Southern California Edison | Fair Value, Measurements, Recurring | Stocks
Nuclear Decommissioning Trusts Disclosures
Fair Value	1,710	1,765
Southern California Edison | Fair Value, Measurements, Recurring | Municipal bonds
Nuclear Decommissioning Trusts Disclosures
Fair Value	1,194	970
Southern California Edison | Fair Value, Measurements, Recurring | U.S. government and agency securities
Nuclear Decommissioning Trusts Disclosures
Fair Value	852	1,115
Southern California Edison | Fair Value, Measurements, Recurring | Corporate bonds
Nuclear Decommissioning Trusts Disclosures
Fair Value	636	679
Southern California Edison | Fair Value, Measurements, Recurring | Short-term investments and receivables/payables
Nuclear Decommissioning Trusts Disclosures
Fair Value	174	33
Repurchase agreements payable	$ 90	$ 41