Regulatory Assets and Liabilities (Regulatory Balancing Accounts) (Details) (Regulatory balancing accounts, USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Regulatory balancing accounts | Energy resource recovery account
Regulatory Assets and Liabilities
Net Regulatory Assets Pertaining to Balancing Accounts	$ 1,028	$ 1,005
Regulatory balancing accounts | Four Corners memorandum account
Regulatory Assets and Liabilities
Net Regulatory Assets Pertaining to Balancing Accounts	0	145
Regulatory balancing accounts | New system generation balancing account
Regulatory Assets and Liabilities
Net Regulatory Assets Pertaining to Balancing Accounts	35	132
Regulatory balancing accounts | Public purpose programs and energy efficiency programs
Regulatory Assets and Liabilities
Net Regulatory Assets Pertaining to Balancing Accounts	(874)	(1,152)
Regulatory balancing accounts | Base rate recovery balancing account
Regulatory Assets and Liabilities
Net Regulatory Assets Pertaining to Balancing Accounts	(5)	(247)
Regulatory balancing accounts | Greenhouse gas auction revenue
Regulatory Assets and Liabilities
Net Regulatory Assets Pertaining to Balancing Accounts	(182)	(385)
Regulatory balancing accounts | FERC balancing accounts
Regulatory Assets and Liabilities
Net Regulatory Assets Pertaining to Balancing Accounts	(32)	(59)
Regulatory balancing accounts | Other
Regulatory Assets and Liabilities
Net Regulatory Assets Pertaining to Balancing Accounts	(104)	0
Regulatory balancing accounts | Liability
Regulatory Assets and Liabilities
Net Regulatory Assets Pertaining to Balancing Accounts	(331)	(554)
Southern California Edison | Regulatory balancing accounts | Generator settlements
Regulatory Assets and Liabilities
Net Regulatory Assets Pertaining to Balancing Accounts	$ (197)	$ 7