Regulatory Assets and Liabilities (Regulatory Balancing Accounts) (Details) (Southern California Edison, USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Regulatory balancing accounts | Energy resource recovery account
Regulatory Assets and Liabilities
Net liability	$ 683	$ 1,028
Regulatory balancing accounts | New system generation balancing account
Regulatory Assets and Liabilities
Net liability	(63)	35
Refunds of excess revenue | Significant Components
Regulatory Assets and Liabilities
Net liability	(469)	(331)
Refunds of excess revenue | Public purpose programs and energy efficiency programs
Regulatory Assets and Liabilities
Net liability	(851)	(874)
Refunds of excess revenue | Base rate recovery balancing account
Regulatory Assets and Liabilities
Net liability	67	(5)
Refunds of excess revenue | Greenhouse gas auction revenue
Regulatory Assets and Liabilities
Net liability	(218)	(182)
Refunds of excess revenue | FERC balancing accounts
Regulatory Assets and Liabilities
Net liability	(9)	(32)
Refunds of excess revenue | Generator settlements
Regulatory Assets and Liabilities
Net liability	0	(197)
Refunds of excess revenue | Other
Regulatory Assets and Liabilities
Net liability	$ (78)	$ (104)