Regulatory Assets and Liabilities (Schedule of Net Regulatory Balancing Accounts) (Details) - Southern California Edison - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Regulatory balancing accounts | Energy resource recovery account
Regulatory Assets and Liabilities
Asset (liability)	$ 228	$ (20)
Regulatory balancing accounts | New system generation balancing account
Regulatory Assets and Liabilities
Asset (liability)	(175)	(6)
Refunds of excess revenue | Net regulatory balancing accounts
Regulatory Assets and Liabilities
Asset (liability)	(1,702)	(1,715)
Refunds of excess revenue | Public purpose programs and energy efficiency programs
Regulatory Assets and Liabilities
Asset (liability)	(1,064)	(992)
Refunds of excess revenue | Tax accounting memorandum account and pole loading balancing account
Regulatory Assets and Liabilities
Asset (liability)	(197)	(142)
Refunds of excess revenue | Base rate recovery balancing account
Regulatory Assets and Liabilities
Asset (liability)	(257)	(426)
Refunds of excess revenue | Department of Energy litigation memorandum account
Regulatory Assets and Liabilities
Asset (liability)	(156)	(122)
Refunds of excess revenue | Greenhouse gas auction revenue
Regulatory Assets and Liabilities
Asset (liability)	24	31
Refunds of excess revenue | FERC balancing accounts
Regulatory Assets and Liabilities
Asset (liability)	(136)	(69)
Refunds of excess revenue | Other
Regulatory Assets and Liabilities
Asset (liability)	$ 31	$ 31