Regulatory Assets and Liabilities (Schedule of Regulatory Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Regulatory Liabilities [Line Items]
Current regulatory liabilities	$ 1,121	$ 756
Regulatory assets	703	350
Long-term regulatory liabilities	8,614	5,726
SCE
Regulatory Liabilities [Line Items]
Current regulatory liabilities	1,121	756
Regulatory assets	703	350
Long-term regulatory liabilities	8,614	5,726
Total regulatory liabilities	9,735	6,482
SCE | Regulatory balancing accounts
Regulatory Liabilities [Line Items]
Long-term regulatory liabilities	1,316	1,180
SCE | Energy derivatives
Regulatory Liabilities [Line Items]
Current regulatory liabilities	74	0
SCE | Other
Regulatory Liabilities [Line Items]
Current regulatory liabilities	38	20
Long-term regulatory liabilities	64	60
SCE | Costs of removal
Regulatory Liabilities [Line Items]
Long-term regulatory liabilities	2,741	2,847
SCE | Re-measurement of deferred taxes
Regulatory Liabilities [Line Items]
Long-term regulatory liabilities	2,892	0
SCE | Recoveries in excess of ARO liabilities
Regulatory Liabilities [Line Items]
Long-term regulatory liabilities	1,575	1,639
SCE | Other postretirement benefits
Regulatory Liabilities [Line Items]
Long-term regulatory liabilities	26	0
Regulatory balancing accounts | SCE
Regulatory Liabilities [Line Items]
Current regulatory liabilities	1,009	736
Regulatory assets	$ 484	$ 135