Regulatory Assets and Liabilities (Regulatory Balancing Accounts) (Details) - Southern California Edison - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Regulatory balancing accounts | Energy resource recovery account
Regulatory Assets and Liabilities
Net liability	$ (364)	$ (439)
Regulatory balancing accounts | New system generation balancing account
Regulatory Assets and Liabilities
Net liability	(189)	(171)
Refunds of excess revenue | Significant Components
Regulatory Assets and Liabilities
Net liability	(2,119)	(2,002)
Refunds of excess revenue | Public purpose programs and energy efficiency programs
Regulatory Assets and Liabilities
Net liability	(817)	(683)
Refunds of excess revenue | Tax accounting memorandum account and pole loading balancing account
Regulatory Assets and Liabilities
Net liability	(278)	(248)
Refunds of excess revenue | Base rate recovery balancing account
Regulatory Assets and Liabilities
Net liability	(234)	(319)
Refunds of excess revenue | Greenhouse gas auction revenue
Regulatory Assets and Liabilities
Net liability	(156)	(75)
Refunds of excess revenue | FERC balancing accounts
Regulatory Assets and Liabilities
Net liability	43	74
Refunds of excess revenue | Generator settlements
Regulatory Assets and Liabilities
Net liability	0	(4)
Refunds of excess revenue | Other
Regulatory Assets and Liabilities
Net liability	$ (124)	$ (137)