Regulatory Assets and Liabilities (Schedule of Net Regulatory Balancing Accounts) (Details) - Southern California Edison - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Regulatory balancing accounts | Energy resource recovery account
Regulatory Assets and Liabilities
Asset (liability)	$ 30	$ (20)
Regulatory balancing accounts | New system generation balancing account
Regulatory Assets and Liabilities
Asset (liability)	(97)	(6)
Refunds of excess revenue | Significant Components
Regulatory Assets and Liabilities
Asset (liability)	(1,811)	(1,715)
Refunds of excess revenue | Public purpose programs and energy efficiency programs
Regulatory Assets and Liabilities
Asset (liability)	(1,056)	(992)
Refunds of excess revenue | Tax accounting memorandum account and pole loading balancing account
Regulatory Assets and Liabilities
Asset (liability)	(136)	(142)
Refunds of excess revenue | Base rate recovery balancing account
Regulatory Assets and Liabilities
Asset (liability)	(360)	(426)
Refunds of excess revenue | Department of Energy litigation memorandum account
Regulatory Assets and Liabilities
Asset (liability)	(123)	(122)
Refunds of excess revenue | Greenhouse gas auction revenue
Regulatory Assets and Liabilities
Asset (liability)	(3)	31
Refunds of excess revenue | FERC balancing accounts
Regulatory Assets and Liabilities
Asset (liability)	(93)	(69)
Refunds of excess revenue | Other
Regulatory Assets and Liabilities
Asset (liability)	$ 27	$ 31