Related-Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Related Party Transaction [Line Items]
Wildfire Insurance Fund expense	$ 83	$ 0	$ 167	$ 0
Southern California Edison
Related Party Transaction [Line Items]
Wildfire Insurance Fund expense	83	0	167	0
Southern California Edison | Subsidiary of Common Parent | Wildfire Liability Insurance
Related Party Transaction [Line Items]
Wildfire insurance premiums	176	74	176	260
Long-term insurance receivable due from affiliate	803		803		$ 803
Prepaid insurance	1		1		$ 10
Wildfire Insurance Fund expense	$ 50	$ 41	$ 100	$ 72