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Regulatory Assets and Liabilities (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended |
--- | --- | ---
Dec. 31, 2012 | Dec. 31, 2011
Regulatory Assets |  |  |  |
Regulatory Assets, Current | $ 572 |  | $ 494 |
Regulatory Asset, Long-term | 6,422 |  | 5,466 |
Regulatory Liabilities |  |  |  |
Regulatory Liabilities, Current | 536 |  | 670 |
Regulatory Liabilities, Long-term | 5,214 |  | 4,670 |
Southern California Edison |  |  |  |
Regulatory Assets and Liabilities |  |  |  |
Regulatory assets, energy derivatives, low range of contract expiration (in years) | 1 year |  |  |
Regulatory assets, energy derivatives, high range of contract expiration (in years) | 11 years |  |  |
Regulatory assets related to deferred income taxes, recovery period, low range (in years) | 1 year |  |  |
Regulatory assets related to deferred income taxes, recovery period, high range (in years) | 45 years |  |  |
Low end of the range of remaining original amortization (in years) | 1 year |  |  |
High end of the range of remaining original amortization (in years) | 26 years |  |  |
Regulatory Assets |  |  |  |
Regulatory Assets, Current | 572 |  | 494 |
Regulatory Asset, Long-term | 6,422 |  | 5,815 |
Total Regulatory Assets | 6,994 |  | 6,309 |
Regulatory Liabilities |  |  |  |
Regulatory Liabilities, Current | 536 |  | 670 |
Regulatory Liabilities, Long-term | 5,214 |  | 4,670 |
Total Regulatory Liabilities | 5,750 |  | 5,340 |
Southern California Edison | Regulatory balancing accounts |  |  |  |
Regulatory Assets |  |  |  |
Regulatory Assets, Current | 502 |  | 223 |
Regulatory Asset, Long-term | 73 |  | 69 |
Southern California Edison | Energy derivatives |  |  |  |
Regulatory Assets |  |  |  |
Regulatory Assets, Current | 70 |  | 264 |
Regulatory Asset, Long-term | 900 | [1] | 836 | [1]
Southern California Edison | Other |  |  |  |
Regulatory Assets |  |  |  |
Regulatory Assets, Current | 0 |  | 7 |
Regulatory Asset, Long-term | 360 |  | 298 |
Regulatory Liabilities |  |  |  |
Regulatory Liabilities, Current | 52 |  | 9 |
Regulatory Liabilities, Long-term | 7 |  | 4 |
Southern California Edison | Deferred income taxes, net |  |  |  |
Regulatory Assets |  |  |  |
Regulatory Asset, Long-term | 2,663 |  | 2,020 |
Southern California Edison | Pensions and other postretirement benefits |  |  |  |
Regulatory Assets |  |  |  |
Regulatory Asset, Long-term | 1,550 |  | 1,703 |
Southern California Edison | Unamortized investments, net |  |  |  |
Regulatory Assets and Liabilities |  |  |  |
Return rate earned on assets included in rate base (as a percent) | 8.74% |  | 8.74% |
Regulatory Assets |  |  |  |
Regulatory Asset, Long-term | 507 |  | 484 |
Southern California Edison | Unamortized loss on reacquired debt |  |  |  |
Regulatory Assets |  |  |  |
Regulatory Asset, Long-term | 228 |  | 249 |
Southern California Edison | Nuclear-related investment, net |  |  |  |
Regulatory Assets |  |  |  |
Regulatory Asset, Long-term | 141 |  | 156 |
Southern California Edison | Regulatory Balancing Accounts, Liabilities |  |  |  |
Regulatory Liabilities |  |  |  |
Regulatory Liabilities, Current | 484 |  | 661 |
Regulatory Liabilities, Long-term | 1,091 |  | 864 |
Southern California Edison | Costs of Removal |  |  |  |
Regulatory Liabilities |  |  |  |
Regulatory Liabilities, Long-term | 2,731 |  | 2,697 |
Southern California Edison | Asset Retirement Obligations |  |  |  |
Regulatory Liabilities |  |  |  |
Regulatory Liabilities, Long-term | 1,385 |  | 1,105 |
Legacy Meters | Southern California Edison | Unamortized investments, net |  |  |  |
Regulatory Assets and Liabilities |  |  |  |
Return rate earned on assets included in rate base (as a percent) | 6.46% |  |  |
Edison Mission Energy | Southern California Edison | Energy derivatives |  |  |  |
Regulatory Assets |  |  |  |
Regulatory Asset, Long-term |  |  | $ 349 |
[1] | Included in 2011 is the regulatory offset of a power purchase agreement between SCE and EME with a fair market value of $349 million, which was eliminated in the Edison International consolidated financial statements.

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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 + Details
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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 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 + Details
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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 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 + Details
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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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