Commitments and Contingencies (Southern California Wildfires and Mudslides) (Details) a in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Nov. 30, 2018 USD ($) a structure fatality	Jan. 31, 2019 claims	Sep. 30, 2018 claims	Jan. 01, 2018 structure fatality	Dec. 31, 2017 a structure fatality
Loss Contingencies [Line Items]
Wildfire-related claims	$ 4,669,000,000	$ 4,669,000,000
2017/2018 Wildfire/Mudslide Event
Loss Contingencies [Line Items]
Derivative lawsuits | claims					2
San Onofre OII
Loss Contingencies [Line Items]
Derivative lawsuits | claims				2
Southern California Edison
Loss Contingencies [Line Items]
High fire risk service area, percent	35.00%
Wildfire-related claims	$ 4,669,000,000	4,669,000,000
Wildfire-specific insurance coverage		1,000,000,000	$ 300,000,000
Self-insured retention		10,000,000
Other general liability insurance coverage		450,000,000
Southern California Edison | Thomas and Koenigstein Fires
Loss Contingencies [Line Items]
Acres burned | a							280
Structures destroyed | structure							1,343
Fatalities | fatality							2
Southern California Edison | Woolsey Fire
Loss Contingencies [Line Items]
Acres burned | a			100
Structures destroyed | structure			1,643
Fatalities | fatality			3
Structures damaged | structure			364
Wildfire-specific insurance coverage		1,000,000,000
Self-insured retention		10,000,000
Southern California Edison | Montecito Mudslides
Loss Contingencies [Line Items]
Structures destroyed | structure						135
Fatalities | fatality						21
Structures damaged | structure						324
Additional presumed fatalities | fatality						2
Southern California Edison | 2017/2018 Wildfire/Mudslide Event
Loss Contingencies [Line Items]
Wildfire-related claims	4,700,000,000	4,700,000,000
Expected insurance recoveries	2,000,000,000	2,000,000,000
Expected revenue from FERC customers	$ 135,000,000	135,000,000
Total after-tax charge		$ 1,800,000,000