Regulatory Assets and Liabilities (Liabilities) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Regulatory Liabilities [Line Items]
Current regulatory liabilities	$ 524	$ 569
Long-term regulatory liabilities	8,881	8,589
SCE
Regulatory Liabilities [Line Items]
Current regulatory liabilities	524	569
Long-term regulatory liabilities	8,881	8,589
Total regulatory liabilities	9,405	9,158
SCE | Revenue subject to refund
Regulatory Liabilities [Line Items]
Current regulatory liabilities	427	471
Long-term regulatory liabilities	1,279	1,062
SCE | Energy derivatives
Regulatory Liabilities [Line Items]
Current regulatory liabilities	84	87
SCE | Other regulatory assets or liabilities
Regulatory Liabilities [Line Items]
Current regulatory liabilities	13	11
Long-term regulatory liabilities	45	48
SCE | Costs of removal
Regulatory Liabilities [Line Items]
Long-term regulatory liabilities	2,727	2,595
SCE | Re-measurement of deferred taxes
Regulatory Liabilities [Line Items]
Long-term regulatory liabilities	2,256	2,283
SCE | Recoveries in excess of ARO liabilities
Regulatory Liabilities [Line Items]
Long-term regulatory liabilities	1,901	1,930
SCE | Other postretirement benefits
Regulatory Liabilities [Line Items]
Long-term regulatory liabilities	$ 673	$ 671