Regulatory Assets and Liabilities (Schedule of Regulatory Liabilities) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Regulatory Liabilities [Line Items]
Current regulatory liabilities	$ 1,281	$ 756
Long-term regulatory liabilities	5,858	5,726
Southern California Edison
Regulatory Liabilities [Line Items]
Current regulatory liabilities	1,281	756
Long-term regulatory liabilities	5,858	5,726
Total regulatory liabilities	7,139	6,482
Southern California Edison | Regulatory balancing accounts
Regulatory Liabilities [Line Items]
Current regulatory liabilities	1,188	736
Long-term regulatory liabilities	1,344	1,180
Southern California Edison | San Onofre MHI arbitration award
Regulatory Liabilities [Line Items]
Current regulatory liabilities	47	0
Southern California Edison | Other
Regulatory Liabilities [Line Items]
Current regulatory liabilities	46	20
Long-term regulatory liabilities	59	60
Southern California Edison | Costs of removal
Regulatory Liabilities [Line Items]
Long-term regulatory liabilities	2,736	2,847
Southern California Edison | Recoveries in excess of ARO liabilities
Regulatory Liabilities [Line Items]
Long-term regulatory liabilities	$ 1,719	$ 1,639