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, 2016 USD ($) $ / MWh $ / MMBTU MW	Dec. 31, 2015 USD ($) $ / MWh $ / MMBTU MW
Congestion revenue rights | Market simulation model and auction prices
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value, Assets | $	$ 125	$ 152
Fair Value, Liabilities | $	$ 0	$ 0
Congestion revenue rights | Market simulation model and auction prices | Load forecast | Minimum
Quantitative Information About Level 3 Measurements [Line Items]
Fair value inputs, power units (in megawatts) | MW	6,289	6,289
Congestion revenue rights | Market simulation model and auction prices | Load forecast | Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Fair value inputs, power units (in megawatts) | MW	24,349	24,349
Congestion revenue rights | Market simulation model and auction prices | Power prices | Minimum
Quantitative Information About Level 3 Measurements [Line Items]
Fair value inputs, price level ($ per MWh)	0.00	0.00
Congestion revenue rights | Market simulation model and auction prices | Power prices | Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Fair value inputs, price level ($ per MWh)	110.44	110.44
Congestion revenue rights | Market simulation model and auction prices | Gas prices | Minimum
Quantitative Information About Level 3 Measurements [Line Items]
Fair value inputs, price level ($ per MWh) | $ / MMBTU	1.98	1.98
Congestion revenue rights | Market simulation model and auction prices | Gas prices | Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Fair value inputs, price level ($ per MWh) | $ / MMBTU	5.72	5.72
Tolling | Option model
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value, Assets | $	$ 3	$ 10
Fair Value, Liabilities | $	$ 1,286	$ 1,297
Tolling | Option model | Power prices | Minimum
Quantitative Information About Level 3 Measurements [Line Items]
Fair value inputs, price level ($ per MWh)	24.03	24.15
Expected volatility rate (as a percent)	27.00%	26.00%
Tolling | Option model | Power prices | Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Fair value inputs, price level ($ per MWh)	48.40	46.93
Expected volatility rate (as a percent)	43.00%	38.00%
Tolling | Option model | Power prices | Weighted Average
Quantitative Information About Level 3 Measurements [Line Items]
Fair value inputs, price level ($ per MWh)	34.30	34.80
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)	14.00%	15.00%
Tolling | Option model | Gas prices | Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Expected volatility rate (as a percent)	46.00%	58.00%
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%