Commitments and Contingencies (Contingencies) (Details) a in Thousands, $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2017 USD ($) a cases structure fatality	Dec. 31, 2017 USD ($) a cases structure fatality	Jan. 31, 2018 structure fatality
December 2017 Wildfires
Loss Contingencies [Line Items]
Acres burned | a	280	280
Structures destroyed | structure	1,063	1,063
Structures damaged | structure	280	280
Fatalities | fatality	2	2
Capital expenditures related to restoration of service	$ 35.0
Loss Contingency, Number of Plaintiffs | cases		4
Lawsuits | cases	6	6
Montecito Mudslides | Subsequent event
Loss Contingencies [Line Items]
Structures destroyed | structure			135
Structures damaged | structure			324
Fatalities | fatality			21
Additional fatalities presumed | fatality			2
SCE
Loss Contingencies [Line Items]
Wildfire insurance coverage	$ 1,000.0	$ 1,000.0
Self insurance retention per wildfire occurrence	10.0	10.0
Other general liability insurance coverage	450.0	450.0
Threshold for wildfire claims	300.0	300.0
The Utilities
Loss Contingencies [Line Items]
Funding commitment for GHG Reduction Program	$ 25.0	25.0
Funding obligation reduction		12.5
San Onofre | SCE
Loss Contingencies [Line Items]
Proceeds received		72.0
Arbitration with Mitsubishi Heavy Industries | San Onofre | SCE
Loss Contingencies [Line Items]
Proceeds received		$ 47.0