Fair Value Measurements (Quantitative Information About Level 3 Fair Value Measurements) (Details) (Southern California Edison, Level 3, USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2015 MW		Dec. 31, 2014 MW
Congestion revenue rights | Market simulation model
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value, Assets	297		317
Fair Value, Liabilities	0		0
Congestion revenue rights | Market simulation model | Load Forecast | Minimum
Quantitative Information About Level 3 Measurements [Line Items]
Fair value inputs, power units (in megawatts)	7,630		7,630
Congestion revenue rights | Market simulation model | Load Forecast | Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Fair value inputs, power units (in megawatts)	25,431		25,431
Congestion revenue rights | Market simulation model | Power Prices | Minimum
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, Price Level ($ per MWh)	1.65	[1]	1.65	[1]
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	[1]	109.95	[1]
Congestion revenue rights | Market simulation model | Gas Prices | Minimum
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, Price Level ($ per MWh)	3.65	[2]	3.65	[2]
Congestion revenue rights | Market simulation model | Gas Prices | Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, Price Level ($ per MWh)	6.53	[2]	6.53	[2]
Tolling | Option model
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value, Assets	9		4
Fair Value, Liabilities	1,275		1,175
Tolling | Option model | Power Prices | Minimum
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, Price Level ($ per MWh)	28.00		30.60
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 ($ per MWh)	54.80		61.40
Expected volatility rate (as a percent)	37.00%		42.00%
Tolling | Option model | Power Prices | Weighted Average
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, Price Level ($ per MWh)	40.10		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)	16.00%		13.00%
Tolling | Option model | Gas Prices | Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Expected volatility rate (as a percent)	40.00%		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%

[1] Prices are in dollars per megawatt-hour.

[2] Prices are in dollars per million British thermal units.