Regulatory Assets and Liabilities (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Regulatory Assets
Regulatory Assets, Current	$ 672	$ 572
Regulatory Asset, Long-term	6,518	6,422
Regulatory Liabilities
Regulatory Liabilities, Current	443	536
Regulatory Liabilities, Long-term	5,470	5,214
Southern California Edison
Regulatory Assets
Regulatory Assets, Current	672	572
Regulatory Asset, Long-term	6,518	6,422
Total Regulatory Assets	7,190	6,994
Regulatory Liabilities
Regulatory Liabilities, Current	443	536
Regulatory Liabilities, Long-term	5,470	5,214
Total Regulatory Liabilities	5,913	5,750
Southern California Edison \| Regulatory balancing accounts
Regulatory Assets
Regulatory Assets, Current	624	502
Regulatory Asset, Long-term	76	73
Southern California Edison \| Energy derivatives
Regulatory Assets
Regulatory Assets, Current	48	70
Regulatory Asset, Long-term	974	900
Southern California Edison \| Other
Regulatory Assets
Regulatory Asset, Long-term	364	360
Regulatory Liabilities
Regulatory Liabilities, Current	60	52
Regulatory Liabilities, Long-term	7	7
Southern California Edison \| Deferred income taxes, net
Regulatory Assets
Regulatory Asset, Long-term	2,718	2,663
Southern California Edison \| Pensions and other postretirement benefits
Regulatory Assets
Regulatory Asset, Long-term	1,539	1,550
Southern California Edison \| Unamortized investments, net
Regulatory Assets
Regulatory Asset, Long-term	487	507
Southern California Edison \| Unamortized loss on reacquired debt
Regulatory Assets
Regulatory Asset, Long-term	222	228
Southern California Edison \| Nuclear-related investment, net
Regulatory Assets
Regulatory Asset, Long-term	138	141
Southern California Edison \| Regulatory balancing accounts
Regulatory Liabilities
Regulatory Liabilities, Current	383	484
Regulatory Liabilities, Long-term	1,156	1,091
Southern California Edison \| Costs of Removal
Regulatory Liabilities
Regulatory Liabilities, Long-term	2,769	2,731
Southern California Edison \| Asset Retirement Obligations
Regulatory Liabilities
Regulatory Liabilities, Long-term	$ 1,538	$ 1,385

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- Definition

The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 71

-Paragraph 9, 10

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 980

-SubTopic 340

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382

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- Definition

Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are expected to be recovered through revenue sources within one year or the normal operating cycle, if longer. Such costs are capitalized if they meet both of the following criteria: a. It is probable that future revenue in an amount at least equal to the capitalized cost will result from inclusion of that cost in allowable costs for rate-making purposes. b. Based on available evidence, the future revenue will be provided to permit recovery of the previously incurred cost rather than to provide for expected levels of similar future costs. If the revenue will be provided through an automatic rate-adjustment clause, this criterion requires that the regulator's intent clearly be to permit recovery of the previously incurred cost.

+ References

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- Definition

Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are not expected to be recovered through revenue sources within one year or the normal operating cycle if longer.

+ References

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- Definition

The amount for the individual regulatory liability as itemized in a table of regulatory liabilities as of the end of the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 71

-Paragraph 11

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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- Definition

The amount for the individual regulatory current liability as itemized in a table of regulatory current liabilities as of the end of the period.

+ References

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- Definition

The amount for the individual regulatory noncurrent liability as itemized in a table of regulatory noncurrent liabilities as of the end of the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.24)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 71

-Paragraph 11

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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