Regulatory Assets and Liabilities (Schedule of Net Regulatory Balancing Accounts) (Details) - Southern California Edison - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Nov. 30, 2018	Mar. 31, 2019
Regulatory Assets and Liabilities
Asset (liability)			$ 107
Wildfire-specific insurance coverage	$ 1,000	$ 300
Regulatory balancing accounts | Energy resource recovery account
Regulatory Assets and Liabilities
Asset (liability)	815		927
Regulatory balancing accounts | New system generation balancing account
Regulatory Assets and Liabilities
Asset (liability)	(74)		(96)
Refunds of excess revenue | Net regulatory balancing accounts
Regulatory Assets and Liabilities
Asset (liability)	(1,250)		(1,097)
Refunds of excess revenue | Public purpose programs and energy efficiency programs
Regulatory Assets and Liabilities
Asset (liability)	(1,200)		(1,304)
Refunds of excess revenue | Tax accounting memorandum account and pole loading balancing account
Regulatory Assets and Liabilities
Asset (liability)	28		(128)
Refunds of excess revenue | Base revenue requirement balancing account
Regulatory Assets and Liabilities
Asset (liability)	(628)		(282)
Refunds of excess revenue | DOE litigation memorandum account
Regulatory Assets and Liabilities
Asset (liability)	(69)		(69)
Refunds of excess revenue | Greenhouse gas auction revenue and low carbon fuel standard revenue
Regulatory Assets and Liabilities
Asset (liability)	(81)		(150)
Refunds of excess revenue | FERC balancing accounts
Regulatory Assets and Liabilities
Asset (liability)	(180)		(139)
Refunds of excess revenue | Catastrophic event memorandum account
Regulatory Assets and Liabilities
Asset (liability)	144		95
Refunds of excess revenue | Wildfire expense memorandum account
Regulatory Assets and Liabilities
Asset (liability)	128		41
Refunds of excess revenue | Other
Regulatory Assets and Liabilities
Asset (liability)	$ (133)		$ 8