Fair Value Measurements (Quantitative Information About Level 3 Fair Value Measurements) (Details) (Southern California Edison, Level 3, USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014 MW	Dec. 31, 2013 MW
Congestion Revenue Rights | Market Simulation Model
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value, Assets	$ 339	$ 366
Fair Value, Liabilities	0	0
Congestion Revenue Rights | Market Simulation Model | Load Forecast | Minimum
Quantitative Information About Level 3 Measurements [Line Items]
Fair value inputs, power units (in megawatts)	7,630	7,603
Congestion Revenue Rights | Market Simulation Model | Load Forecast | Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Fair value inputs, power units (in megawatts)	25,431	24,896
Congestion Revenue Rights | Market Simulation Model | Power Prices | Minimum
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, Price Level	1.65	(9.86)
Congestion Revenue Rights | Market Simulation Model | Power Prices | Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, Price Level	109.95	108.56
Congestion Revenue Rights | Market Simulation Model | Gas Prices | Minimum
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, Price Level	3.65	3.50
Congestion Revenue Rights | Market Simulation Model | Gas Prices | Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, Price Level	6.53	7.10
Tolling | Option Model
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value, Assets	0	5
Fair Value, Liabilities	$ 1,095	$ 1,175
Tolling | Option Model | Power Prices | Minimum
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, Price Level	36.80	38.00
Expected volatility rate (as a percent)	26.00%	25.00%
Tolling | Option Model | Power Prices | Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, Price Level	65.60	63.90
Expected volatility rate (as a percent)	45.00%	45.00%
Tolling | Option Model | Power Prices | Weighted Average
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, Price Level	48.90	47.40
Expected volatility rate (as a percent)	31.00%	30.00%
Tolling | Option Model | Gas Prices | Minimum
Quantitative Information About Level 3 Measurements [Line Items]
Expected volatility rate (as a percent)	12.00%	16.00%
Tolling | Option Model | Gas Prices | Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Expected volatility rate (as a percent)	40.00%	35.00%
Tolling | Option Model | Gas Prices | Weighted Average
Quantitative Information About Level 3 Measurements [Line Items]
Expected volatility rate (as a percent)	19.00%	21.00%