Fair Value Measurements (Quantitative Information About Level 3 Fair Value Measurements) (Details) - Southern California Edison - Level 3 $ in Millions	6 Months Ended	12 Months Ended
Jun. 30, 2017 USD ($) $ / MWh $ / MMBTU MW	Dec. 31, 2016 USD ($) $ / MWh $ / MMBTU MW
Congestion revenue rights \| Market simulation model and auction prices
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value, Assets \| $	$ 36	$ 67
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	3,708	3,708
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	22,840	22,840
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)	3.65	3.65
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)	99.58	99.58
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	2.51	2.51
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	4.87	4.87
Tolling \| Option model
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value, Assets \| $	$ 0	$ 0
Fair Value, Liabilities \| $	$ 1,043	$ 1,154
Tolling \| Option model \| Power prices \| Minimum
Quantitative Information About Level 3 Measurements [Line Items]
Fair value inputs, price level ($ per MWh)	23.41	23.40
Expected volatility rate	27.00%	29.00%
Tolling \| Option model \| Power prices \| Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Fair value inputs, price level ($ per MWh)	47.10	51.24
Expected volatility rate	67.00%	71.00%
Tolling \| Option model \| Power prices \| Weighted Average
Quantitative Information About Level 3 Measurements [Line Items]
Fair value inputs, price level ($ per MWh)	33.16	34.70
Expected volatility rate	34.00%	40.00%
Tolling \| Option model \| Gas prices \| Minimum
Quantitative Information About Level 3 Measurements [Line Items]
Expected volatility rate	13.00%	15.00%
Tolling \| Option model \| Gas prices \| Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Expected volatility rate	43.00%	48.00%
Tolling \| Option model \| Gas prices \| Weighted Average
Quantitative Information About Level 3 Measurements [Line Items]
Expected volatility rate	21.00%	20.00%

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Fair Value Inputs, Price Level

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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Measure of dispersion, in percentage terms (for instance, the standard deviation or variance), for a given stock price.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
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Fair value of financial and nonfinancial obligations.

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