Regulatory Assets and Liabilities (Schedule of Regulatory Assets) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Regulatory Assets [Line Items]
Current regulatory assets	$ 394	$ 350
Long-term regulatory assets	7,674	7,455
Environmental remediation
Regulatory Assets [Line Items]
Long-term regulatory assets	125	126
Southern California Edison
Regulatory Assets [Line Items]
Current regulatory assets	394	350
Long-term regulatory assets	7,674	7,455
Total regulatory assets	8,068	7,805
Southern California Edison | Regulatory balancing accounts
Regulatory Assets [Line Items]
Current regulatory assets	139	135
Long-term regulatory assets	68	66
Southern California Edison | Energy derivatives
Regulatory Assets [Line Items]
Current regulatory assets	186	150
Long-term regulatory assets	996	947
Southern California Edison | Unamortized investments, net of accumulated amortization
Regulatory Assets [Line Items]
Current regulatory assets	37	49
Southern California Edison | Other
Regulatory Assets [Line Items]
Current regulatory assets	32	16
Long-term regulatory assets	11	7
Southern California Edison | Deferred income taxes, net of liabilities
Regulatory Assets [Line Items]
Long-term regulatory assets	4,689	4,478
Southern California Edison | Pensions and other postretirement benefits
Regulatory Assets [Line Items]
Long-term regulatory assets	711	710
Southern California Edison | Unamortized investments, net of accumulated amortization
Regulatory Assets [Line Items]
Long-term regulatory assets	79	80
Southern California Edison | San Onofre
Regulatory Assets [Line Items]
Long-term regulatory assets	815	857
Southern California Edison | Unamortized loss on reacquired debt
Regulatory Assets [Line Items]
Long-term regulatory assets	$ 180	$ 184