Commitments and Contingencies (San Onofre CPUC Proceedings) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 19, 2017
Regulatory Assets [Line Items]
Regulatory assets	$ 4,914.0	$ 7,455.0
Impairment and other charges	738.0	21.0	$ 5.0
SCE
Regulatory Assets [Line Items]
Regulatory assets	4,914.0	7,455.0
Impairment and other charges	716.0	0.0	$ 0.0
SCE | Utility Shareholder Agreement
Regulatory Assets [Line Items]
Impairment and other charges	143.0
SCE | San Onofre
Regulatory Assets [Line Items]
Regulatory assets	72.0	$ 857.0		$ 775.0
The Utilities
Regulatory Assets [Line Items]
Funding commitment for GHG Reduction Program	25.0
Funding obligation reduction	$ 12.5
SDG&E | San Onofre
Regulatory Assets [Line Items]
Regulatory assets				$ 151.0