Fair Value Measurements (Quantitative Information About Level 3 Fair Value Measurements) (Details) - Southern California Edison - Level 3 $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2015 USD ($) $ / MWh $ / MMBTU MW	Dec. 31, 2014 USD ($) $ / MWh $ / MMBTU MW
Congestion revenue rights | Market simulation model
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value, Assets | $	$ 258	$ 317
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) | MW	7,630	7,630
Congestion revenue rights | Market simulation model | Load Forecast | Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Fair value inputs, power units (in megawatts) | MW	25,431	25,431
Congestion revenue rights | Market simulation model | Power Prices | Minimum
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, Price Level ($ per MWh)	1.65	1.65
Congestion revenue rights | Market simulation model | Power Prices | Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, Price Level ($ per MWh)	109.95	109.95
Congestion revenue rights | Market simulation model | Gas Prices | Minimum
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, Price Level ($ per MWh) | $ / MMBTU	3.65	3.65
Congestion revenue rights | Market simulation model | Gas Prices | Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, Price Level ($ per MWh) | $ / MMBTU	6.53	6.53
Tolling | Option model
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value, Assets | $	$ 11	$ 4
Fair Value, Liabilities | $	$ 1,359	$ 1,207
Tolling | Option model | Power Prices | Minimum
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, Price Level ($ per MWh)	27.03	30.60
Expected volatility rate (as a percent)	25.00%	25.00%
Tolling | Option model | Power Prices | Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, Price Level ($ per MWh)	47.41	61.40
Expected volatility rate (as a percent)	56.00%	42.00%
Tolling | Option model | Power Prices | Weighted Average
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, Price Level ($ per MWh)	35.80	44.60
Expected volatility rate (as a percent)	30.00%	30.00%
Tolling | Option model | Gas Prices | Minimum
Quantitative Information About Level 3 Measurements [Line Items]
Expected volatility rate (as a percent)	15.00%	13.00%
Tolling | Option model | Gas Prices | Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Expected volatility rate (as a percent)	45.00%	53.00%
Tolling | Option model | Gas Prices | Weighted Average
Quantitative Information About Level 3 Measurements [Line Items]
Expected volatility rate (as a percent)	20.00%	20.00%