Commitments and Contingencies	3 Months Ended
Mar. 31, 2013
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Indemnities Edison International and SCE have various financial and performance guarantees and indemnity agreements which are issued in the normal course of business. The contracts discussed below included performance guarantees. Indemnity Provided as Part of the Acquisition of Mountainview In connection with the acquisition of the Mountainview power plant, SCE agreed to indemnify the seller with respect to specific environmental claims related to SCE's previously owned San Bernardino Generating Station, divested by SCE in 1998 and reacquired in 2004 as part of the Mountainview acquisition. SCE retained certain responsibilities with respect to environmental claims as part of the original divestiture of the station. The aggregate liability for either party to the purchase agreement for damages and other amounts is a maximum of $60 million. This indemnification for environmental liabilities expires on or before March 12, 2033. SCE has not recorded a liability related to this indemnity. Mountainview Filter Cake Indemnity SCE has indemnified the City of Redlands, California in connection with Mountainview's California Energy Commission permit for cleanup or associated actions related to groundwater contaminated by perchlorate due to the disposal of filter cake at the City's solid waste landfill. The obligations under this agreement are not limited to a specific time period or subject to a maximum liability. SCE has not recorded a liability related to this indemnity. Other Indemnities Edison International and SCE provide other indemnifications through contracts entered into in the normal course of business. These are primarily indemnifications against adverse litigation outcomes in connection with underwriting agreements, and indemnities for specified environmental liabilities and income taxes with respect to assets sold. Edison International's and SCE's obligations under these agreements may or may not be limited in terms of time and/or amount, and in some instances Edison International and SCE may have recourse against third parties. Edison International and SCE have not recorded a liability related to these indemnities. The overall maximum amount of the obligations under these indemnifications cannot be reasonably estimated. Contingencies In addition to the matters disclosed in these Notes, Edison International and SCE are involved in other legal, tax and regulatory proceedings before various courts and governmental agencies regarding matters arising in the ordinary course of business. Edison International and SCE believe the outcome of these other proceedings will not, individually or in the aggregate, materially affect its results of operations or liquidity. San Onofre Outage, Inspection and Repair Issues Replacement steam generators were installed at San Onofre in 2010 and 2011. In the first quarter of 2012, a water leak suddenly occurred in one of the heat transfer tubes in San Onofre's Unit 3 steam generators and the Unit was safely taken off-line. At the time, Unit 2 was off-line for a planned outage when areas of unexpected tube to support structure wear were found. Each Unit will be restarted only when and if SCE determines that it is safe to do so and when start-up has been approved by the NRC pursuant to the terms of a Confirmatory Action Letter (“CAL”) issued by the NRC in March 2012. Both Units have remained off-line for extensive inspections, testing and analysis of their steam generators. In October 2012, SCE submitted to the NRC a response to the CAL and restart plans for Unit 2. SCE proposed to restart Unit 2 under the CAL and operate at a reduced power level (70%) for approximately five months, followed by a mid-cycle scheduled outage and inspection. The NRC has been engaged in conducting a series of inspections, data requests, evaluations, reviews and public meetings about the causes of the steam generator malfunction and damage and to verify that SCE has performed the actions described in the CAL response and as otherwise required by its obligations as a nuclear operator. As part of the NRC's review of the San Onofre outage and proceedings pursuant to the CAL the NRC appointed an Augmented Inspection Team to review SCE's performance. SCE has been advised that the NRC's Office of Investigations has initiated an investigation into the accuracy and completeness of information SCE has provided to the NRC since the outage regarding the San Onofre steam generators. Should the NRC find a deficiency in SCE's performance or provision of information, SCE could be subject to additional NRC actions, including the imposition of penalties, and the findings could be taken into consideration in the CPUC regulatory proceedings described below. Under California Public Utilities Code Section 455.5, SCE is required to notify the CPUC if either of the San Onofre Units has been out of service for nine consecutive months (not including preplanned outages). SCE provided such notice to the CPUC on November 1, 2012 for Unit 3 and December 6, 2012 for Unit 2. In October 2012 the CPUC issued an Order Instituting Investigation (“OII”) that consolidated all San Onofre issues in related regulatory proceedings and considers appropriate cost recovery for all San Onofre costs, including among other costs, the cost of the steam generator replacement project, substitute market power costs, capital expenditures, operations and maintenance costs, and seismic study costs. The Order requires that all San Onofre-related costs incurred on and after January 1, 2012 be tracked in a memorandum account and, to the extent included in rates, collected subject to refund. The first two phases of the OII are focused on these 2012 costs. SCE filed an application in January 2013 seeking a reasonableness determination regarding these costs. The Order also states that the CPUC will determine whether to order the immediate removal, effective as of the date of the order, of all costs related to San Onofre from SCE's rates, with placement of those costs in a deferred debit account pending the return of one or both Units to useful service, or other possible action. Various other parties have filed testimony in the OII asking for the disallowance of some or all of the San Onofre-related costs. The third and fourth phases of the OII will focus on the steam generator replacement project and San Onofre 2013 revenue requirement, respectively. On March 15, 2013, SCE filed its final costs for the San Onofre Steam Generator project, which were within the amount authorized by the CPUC based on SCE's estimate of the costs after adjustment for inflation using the Handy Whitman Index. It is currently expected that the investigation will be conducted in phases that will extend at least into 2014. As of the date of this report, the CPUC has only published a schedule for the first phase of the OII. The steam generators were designed and supplied by MHI and are warranted for an initial period of 20 years from acceptance. MHI is contractually obligated to repair or replace defective items and to pay specified damages for certain repairs. MHI's liability under the purchase agreement is limited to $138 million and excludes consequential damages, defined to include "the cost of replacement power." Such limitations in the contract are subject to applicable exceptions both in the contract and under law. SCE has notified MHI that it believes one or more of such exceptions now apply and that MHI's liability is not limited to $138 million, and MHI has advised SCE that it disagrees. The disagreement may ultimately become subject to dispute resolution procedures set forth in the purchase agreement, including international arbitration. SCE, on behalf of itself and the other San Onofre co-owners, has submitted five invoices to MHI totaling $139 million for steam generator repair costs incurred through February 28, 2013. MHI paid the first invoice of $45 million, while reserving its right to challenge any of the charges in the invoice. In January 2013, MHI advised SCE that it rejected a portion of the first invoice and required further documentation regarding the remainder of the invoice. SCE has recorded its share of the invoice paid as a reduction of repair and inspection costs. San Onofre carries both property damage and outage insurance issued by Nuclear Electric Insurance Limited (“NEIL”) and has placed NEIL on notice of claims under the two policies. The NEIL policies have a number of exclusions and limitations that may reduce or eliminate coverage. As of the date of this report, SCE has filed separate proofs of loss for Unit 2 and Unit 3 under the outage policy covering the period of the outage through December 29, 2012 that total $234 million (SCE's share of which is approximately $183 million). Pursuant to these proofs of loss SCE is seeking the weekly indemnity amounts provided under the outage policy for each Unit. Because the outage is ongoing, SCE has supplemented and will continue to supplement these proofs of loss in the future. SCE has not submitted a proof of loss under the property damage policy. No amounts have been recognized in SCE's financial statements, pending NEIL's response. To the extent any costs are recovered under the outage policy, SCE expects to refund those amounts to customers through the ERRA balancing account. The costs tracked in the memorandum account through March 31, 2013 under the CPUC's OII include approximately $728 million of SCE's authorized revenue requirement associated with operating and maintenance expenses, and depreciation and return on SCE's investment in Unit 2, Unit 3 and common plant. This amount is subject to refund depending on the outcome of the investigation. In 2005, the CPUC authorized expenditures of approximately $525 million ($665 million based on SCE's estimate after adjustment for inflation using the Handy-Whitman Index) for SCE's 78.21% share of the costs to purchase and install the four new steam generators in Units 2 and 3 and remove and dispose of their predecessors. SCE has spent $602 million through March 31, 2013 on the steam generator replacement project. These expenditures remain subject to CPUC reasonableness review and approval. As a result of outages associated with the steam generator inspection and repair, electric power and capacity normally provided by San Onofre are being purchased in the market by SCE . These market power costs are typically recoverable through the ERRA balancing account subject to CPUC reasonableness review, but will now be reviewed as part of the CPUC’s OII proceeding. The cost estimate required in the OII proceeding produce a market power cost estimate that differs from SCE’s prior estimates, as the OII methodology includes cost estimates during planned outage periods (such as for refueling) and estimated foregone energy sales from excess San Onofre production. Estimated market power costs calculated in accordance with the OII methodology were approximately $444 million as of March 31, 2013, net of avoided nuclear fuel costs. Such amount includes costs of approximately $50 million associated with planned outage periods. SCE believes that such costs should be excluded as they would have been incurred even had the replacement steam generators performed as expected. The CPUC will ultimately determine a final methodology for estimating market power costs as it continues its review of the issues in the OII. Future market power costs are uncertain and will be influenced by factors such as when, if, and at what output levels either of the San Onofre Units is returned to service, as well as variations in the cost of power in the market; however, such amounts may be material. Through March 31, 2013, SCE's share of incremental inspection and repair costs totaled $109 million for both Units (not including payments made by MHI as described below), and repairs to restart Unit 2 at the reduced power levels described above were completed. The costs for Unit 2 may increase following NRC review under the CAL. Total incremental repair costs associated with returning Unit 3 to service, and returning both Units to service at originally specified capabilities safely, remain uncertain. SCE recorded its share of payments made to date by MHI ($36 million) as a reduction of incremental inspection and repair costs in 2012. SCE believes that the actions taken and costs incurred in connection with the San Onofre replacement steam generators and outages have been prudent. Accordingly, SCE considers its operating, capital, and market power costs, recoverable through base rates and the ERRA balancing account, as offset by third party recoveries where applicable. SCE cannot provide assurance that either or both Units of San Onofre will be returned to service, that the CPUC will not disallow costs incurred or order refunds to customers of amounts collected in rates, or that SCE will be successful in recovering amounts from third parties. A delay in the restart of San Onofre Unit 2 beyond summer 2013 may impact plans for future operations of both Units. Disallowances of costs and/or refund of amounts received from customers could be material and adversely affect SCE's financial condition, results of operations and cash flows. SCE will pursue recoveries arising from available agreements, but there is no assurance that SCE will recover all of its applicable costs pursuant to these arrangements. EME Chapter 11 Filing On the Petition Date, EME and certain of its wholly-owned subsidiaries filed voluntary petitions for relief under Chapter 11 of the Bankruptcy Code in the Bankruptcy Court. Under the Support Agreement to which EME, Edison International and certain of EME's senior unsecured noteholders are parties, each of them has agreed to support Bankruptcy Court approval of the Settlement Transaction. EME has a customary "fiduciary out" under the Support Agreement. Moreover, the Bankruptcy Court may not approve the Settlement Transaction, or even if the Settlement Transaction is approved, it may not be consummated if certain conditions are not met. If the Settlement Transaction is not approved and consummated, Edison International may not be entitled to the benefits of the Settlement Transaction and it will remain subject to any claims of EME and the noteholders, including claims relating to or arising out of any shared services, the tax allocation agreement, and any other relationships or transactions between the companies. For further information, see Note 16. CPUC Safety and Enforcement Division Investigations San Gabriel Valley Windstorm Investigation In November 2011, a windstorm resulted in significant damage to SCE’s electric system and service outages for SCE customers primarily in the San Gabriel Valley. The CPUC directed its Safety and Enforcement Division (“SED”) to conduct an investigation focused on the cause of the outages, SCE’s service restoration effort, and SCE’s customer communications during the outages. The SED issued its final report on January 11, 2013. The report asserts that SCE and others with whom SCE shares utility poles violated certain CPUC safety rules applicable to overhead line construction, maintenance and operation, which may have caused the failures of affected poles and supporting cables. The report also concludes that SCE’s restoration time was not adequate and makes other assertions. Additionally, the report contends that SCE violated CPUC rules by failing to preserve evidence relevant to the investigation when it did not retain damaged poles that were replaced following the windstorm. If the CPUC issues an OII regarding this matter and SCE is found to have violated any CPUC rules, it could face penalties. SCE is unable to estimate a possible loss or range of loss associated with any penalties that may be imposed by the CPUC on SCE. The final decision in SCE’s 2012 GRC directed SCE to, among other things, make an assessment of a representative sampling of its poles to determine their conformance with current legal standards and report by July 31, 2013 on the results of this assessment. The cost of any large scale review of poles or other equipment for safety compliance, as well as any remediation measures required to assure compliance, could be significant. Malibu Fire Order Instituting Investigation Following a 2007 wildfire in Malibu, California, the CPUC issued an OII to determine if any statutes, CPUC general orders, rules or regulations were violated by SCE or telecomm providers (“OII Respondents”) that shared the use of three failed power poles in the wildfire area. The SED has alleged, among other things, that the poles were overloaded, that the OII Respondents violated the CPUC's rules governing the design, construction and inspection of poles, and that SCE failed to preserve evidence relevant to the investigation and misled the CPUC during its investigation of the fire. In October 2011, the SED proposed that the OII Respondents be assessed penalties of approximately $99 million, with SCE being allocated approximately $50 million of the total. SCE has denied the allegations and believes the proposed penalties are excessive. In September 2012, the CPUC approved a partial settlement between the SED and three telecomm providers. The partial settlement did not resolve any of the claims against SCE or the remaining telecomm provider. In February 2013, SCE was informed that the remaining telecomm provider had reached an agreement to settle with the SED, which remains subject to final documentation and CPUC approval. Four Corners New Source Review Litigation In October 2011, four private environmental organizations filed a CAA citizen lawsuit against the co-owners of Four Corners. The complaint alleges that certain work performed at the Four Corners generating units 4 and 5, over the approximate periods of 1985 – 1986 and 2007 – 2010, constituted plant “major modifications” and the plant's failure to obtain permits and install best available control technology ("BACT") violated the PSD requirements and the New Source Performance Standards of the CAA. The complaint also alleges subsequent and continuing violations of BACT air emissions limits. The lawsuit seeks injunctive and declaratory relief, civil penalties, including a mitigation project and litigation costs. In November 2012, the parties requested a stay of the litigation to allow for settlement discussion, and the matter is currently stayed to April 2013. In November 2010, SCE entered into an agreement to sell its ownership interest in generating units 4 and 5 to APS. The sale remains contingent upon APS obtaining a long-term fuel supply agreement for the plant. As of January 2013, the sale agreement became terminable by either party, but as of the date of this report, the agreement has not been terminated. Under the agreement SCE would remain responsible for its pro rata share of certain environmental liabilities, including penalties arising from environmental violations prior to the sale. SCE is unable to estimate a possible loss or range of loss associated with this matter. Environmental Remediation Edison International records its environmental remediation liabilities when site assessments and/or remedial actions are probable and a range of reasonably likely cleanup costs can be estimated. Edison International reviews its sites and measures the liability quarterly, by assessing a range of reasonably likely costs for each identified site using currently available information, including existing technology, presently enacted laws and regulations, experience gained at similar sites, and the probable level of involvement and financial condition of other potentially responsible parties. These estimates include costs for site investigations, remediation, operation and maintenance, monitoring and site closure. Unless there is a single probable amount, Edison International records the lower end of this reasonably likely range of costs (reflected in "Other long-term liabilities") at undiscounted amounts as timing of cash flows is uncertain. At March 31, 2013, Edison International's recorded estimated minimum liability to remediate its 23 identified material sites (sites in which the upper end of the range of the costs is at least $1 million) at SCE was $124 million, including $91 million related to San Onofre. In addition to its identified material sites, SCE also has 35 immaterial sites for which the total minimum recorded liability was $3 million. Of the $127 million total environmental remediation liability for SCE, $123 million has been recorded as a regulatory asset. SCE expects to recover $31 million through an incentive mechanism that allows SCE to recover 90% of its environmental remediation costs at certain sites (SCE may request to include additional sites) and $92 million through a mechanism that allows SCE to recover 100% of the costs incurred at certain sites through customer rates. Edison International's identified sites include several sites for which there is a lack of currently available information, including the nature and magnitude of contamination, and the extent, if any, that Edison International may be held responsible for contributing to any costs incurred for remediating these sites. Thus, no reasonable estimate of cleanup costs can be made for these sites. The ultimate costs to clean up Edison International's identified sites may vary from its recorded liability due to numerous uncertainties inherent in the estimation process, such as: the extent and nature of contamination; the scarcity of reliable data for identified sites; the varying costs of alternative cleanup methods; developments resulting from investigatory studies; the possibility of identifying additional sites; and the time periods over which site remediation is expected to occur. Edison International believes that, due to these uncertainties, it is reasonably possible that cleanup costs at the identified material sites and immaterial sites could exceed its recorded liability by up to $180 million and $6 million, respectively, all of which is related to SCE. The upper limit of this range of costs was estimated using assumptions least favorable to Edison International among a range of reasonably possible outcomes. SCE expects to clean up and mitigate its identified sites over a period of up to 30 years. Remediation costs for 2013 and in each of the next four years are expected to range from $6 million to $28 million. Costs incurred for both the three months ended March 31, 2013 and 2012 was $2 million. Based upon the CPUC's regulatory treatment of environmental remediation costs incurred at SCE, Edison International believes that costs ultimately recorded will not materially affect its results of operations, financial position or cash flows. There can be no assurance, however, that future developments, including additional information about existing sites or the identification of new sites, will not require material revisions to estimates. Nuclear Insurance Federal law limits public liability claims from a nuclear incident to the amount of available financial protection, which is currently approximately $12.6 billion. SCE and other owners of San Onofre and Palo Verde have purchased the maximum private primary insurance available ($375 million). The balance is covered by a loss sharing program among nuclear reactor licensees. If a nuclear incident at any licensed reactor in the United States results in claims and/or costs which exceed the primary insurance at that plant site, all nuclear reactor licensees could be required to contribute their share of the liability in the form of a deferred premium. Based on its ownership interests, SCE could be required to pay a maximum of approximately $235 million per nuclear incident. However, it would have to pay no more than approximately $35 million per incident in any one year. If the public liability limit above is insufficient, federal law contemplates that additional funds may be appropriated by Congress. This could include an additional assessment on all licensed reactor operators as a measure for raising further federal revenue. NEIL, a mutual insurance company owned by entities with nuclear facilities, issues primary property damage, decontamination and excess property damage and accidental outage insurance policies. At San Onofre and Palo Verde, property damage insurance covers losses up to $500 million, including decontamination costs. Decontamination liability and excess property damage coverage exceeding the primary $500 million also has been purchased in amounts greater than the federal requirement of a minimum of approximately $1.1 billion. Property damage insurance also covers damages caused by acts of terrorism up to specified limits. Additional outage insurance covers part of replacement power expenses during an accident-related nuclear unit outage. If losses at any nuclear facility covered by the arrangement were to exceed the accumulated funds for these insurance programs, SCE could be assessed retrospective premium adjustments of up to approximately $52 million per year. Insurance premiums are charged to operating expense. Wildfire Insurance Severe wildfires in California have given rise to large damage claims against California utilities for fire-related losses alleged to be the result of the failure of electric and other utility equipment. Invoking a California Court of Appeal decision, plaintiffs pursuing these claims have relied on the doctrine of inverse condemnation, which can impose strict liability (including liability for a claimant's attorneys' fees) for property damage. On September 15, 2012, SCE's parent, Edison International, renewed its insurance coverage, which included coverage for SCE's wildfire liabilities up to a $550 million limit (with a self-insured retention of $10 million per wildfire occurrence). Various coverage limitations within the policies that make up the insurance coverage could result in additional self-insured costs in the event of multiple wildfire occurrences during the policy period (September 15, 2012 to August 31, 2013). SCE may experience coverage reductions and/or increased insurance costs in future years. No assurance can be given that future losses will not exceed the limits of SCE's insurance coverage. Spent Nuclear Fuel Under federal law, the Department of Energy ("DOE") is responsible for the selection and construction of a facility for the permanent disposal of spent nuclear fuel and high-level radioactive waste. The DOE did not meet its contractual obligation to begin acceptance of spent nuclear fuel by January 31, 1998. Extended delays by the DOE have led to the construction of costly alternatives and associated siting and environmental issues. Currently, both San Onofre and Palo Verde have interim storage for spent nuclear fuel on site sufficient for the current license period. In June 2010, the United States Court of Federal Claims issued a decision granting SCE and the San Onofre co-owners damages of approximately $142 million to recover costs incurred through December 31, 2005 for the DOE's failure to meet its obligation to begin accepting spent nuclear fuel from San Onofre. SCE received payment from the federal government in the amount of the damage award in November 2011. SCE has returned to the San Onofre co-owners their respective share of the damage award paid. SCE, as operating agent, filed a lawsuit on behalf of the San Onofre owners against the DOE in the Court of Federal Claims in December 2011 seeking damages of approximately $98 million for the period from January 1, 2006 to December 31, 2010 for the DOE's failure to meet its obligation to begin accepting spent nuclear fuel. Additional legal action would be necessary to recover damages incurred after December 31, 2010. Any damages recovered by SCE are subject to CPUC review as to how these amounts would be distributed among customers, shareholders, or to offset fuel decommissioning or storage costs.

Commitments and Contingencies

Indemnities

Edison International and SCE have various financial and performance guarantees and indemnity agreements which are issued in the normal course of business. The contracts discussed below included performance guarantees.

Indemnity Provided as Part of the Acquisition of Mountainview

In connection with the acquisition of the Mountainview power plant, SCE agreed to indemnify the seller with respect to specific environmental claims related to SCE's previously owned San Bernardino Generating Station, divested by SCE in 1998 and reacquired in 2004 as part of the Mountainview acquisition. SCE retained certain responsibilities with respect to environmental claims as part of the original divestiture of the station. The aggregate liability for either party to the purchase agreement for damages and other amounts is a maximum of $60 million. This indemnification for environmental liabilities expires on or before March 12, 2033. SCE has not recorded a liability related to this indemnity.

Mountainview Filter Cake Indemnity

SCE has indemnified the City of Redlands, California in connection with Mountainview's California Energy Commission permit for cleanup or associated actions related to groundwater contaminated by perchlorate due to the disposal of filter cake at the City's solid waste landfill. The obligations under this agreement are not limited to a specific time period or subject to a maximum liability. SCE has not recorded a liability related to this indemnity.

Other Indemnities

Edison International and SCE provide other indemnifications through contracts entered into in the normal course of business. These are primarily indemnifications against adverse litigation outcomes in connection with underwriting agreements, and indemnities for specified environmental liabilities and income taxes with respect to assets sold. Edison International's and SCE's obligations under these agreements may or may not be limited in terms of time and/or amount, and in some instances Edison International and SCE may have recourse against third parties. Edison International and SCE have not recorded a liability related to these indemnities. The overall maximum amount of the obligations under these indemnifications cannot be reasonably estimated.

Contingencies

In addition to the matters disclosed in these Notes, Edison International and SCE are involved in other legal, tax and regulatory proceedings before various courts and governmental agencies regarding matters arising in the ordinary course of business. Edison International and SCE believe the outcome of these other proceedings will not, individually or in the aggregate, materially affect its results of operations or liquidity.

San Onofre Outage, Inspection and Repair Issues

Replacement steam generators were installed at San Onofre in 2010 and 2011. In the first quarter of 2012, a water leak suddenly occurred in one of the heat transfer tubes in San Onofre's Unit 3 steam generators and the Unit was safely taken off-line. At the time, Unit 2 was off-line for a planned outage when areas of unexpected tube to support structure wear were found. Each Unit will be restarted only when and if SCE determines that it is safe to do so and when start-up has been approved by the NRC pursuant to the terms of a Confirmatory Action Letter (“CAL”) issued by the NRC in March 2012. Both Units have remained off-line for extensive inspections, testing and analysis of their steam generators. In October 2012, SCE submitted to the NRC a response to the CAL and restart plans for Unit 2. SCE proposed to restart Unit 2 under the CAL and operate at a reduced power level (70%) for approximately five months, followed by a mid-cycle scheduled outage and inspection.

The NRC has been engaged in conducting a series of inspections, data requests, evaluations, reviews and public meetings about the causes of the steam generator malfunction and damage and to verify that SCE has performed the actions described in the CAL response and as otherwise required by its obligations as a nuclear operator. As part of the NRC's review of the San Onofre outage and proceedings pursuant to the CAL the NRC appointed an Augmented Inspection Team to review SCE's performance. SCE has been advised that the NRC's Office of Investigations has initiated an investigation into the accuracy and completeness of information SCE has provided to the NRC since the outage regarding the San Onofre steam generators. Should the NRC find a deficiency in SCE's performance or provision of information, SCE could be subject to additional NRC actions, including the imposition of penalties, and the findings could be taken into consideration in the CPUC regulatory proceedings described below.

Under California Public Utilities Code Section 455.5, SCE is required to notify the CPUC if either of the San Onofre Units has been out of service for nine consecutive months (not including preplanned outages). SCE provided such notice to the CPUC on November 1, 2012 for Unit 3 and December 6, 2012 for Unit 2. In October 2012 the CPUC issued an Order Instituting Investigation (“OII”) that consolidated all San Onofre issues in related regulatory proceedings and considers appropriate cost recovery for all San Onofre costs, including among other costs, the cost of the steam generator replacement project, substitute market power costs, capital expenditures, operations and maintenance costs, and seismic study costs. The Order requires that all San Onofre-related costs incurred on and after January 1, 2012 be tracked in a memorandum account and, to the extent included in rates, collected subject to refund. The first two phases of the OII are focused on these 2012 costs. SCE filed an application in January 2013 seeking a reasonableness determination regarding these costs. The Order also states that the CPUC will determine whether to order the immediate removal, effective as of the date of the order, of all costs related to San Onofre from SCE's rates, with placement of those costs in a deferred debit account pending the return of one or both Units to useful service, or other possible action. Various other parties have filed testimony in the OII asking for the disallowance of some or all of the San Onofre-related costs. The third and fourth phases of the OII will focus on the steam generator replacement project and San Onofre 2013 revenue requirement, respectively. On March 15, 2013, SCE filed its final costs for the San Onofre Steam Generator project, which were within the amount authorized by the CPUC based on SCE's estimate of the costs after adjustment for inflation using the Handy Whitman Index. It is currently expected that the investigation will be conducted in phases that will extend at least into 2014. As of the date of this report, the CPUC has only published a schedule for the first phase of the OII.

The steam generators were designed and supplied by MHI and are warranted for an initial period of 20 years from acceptance. MHI is contractually obligated to repair or replace defective items and to pay specified damages for certain repairs. MHI's liability under the purchase agreement is limited to $138 million and excludes consequential damages, defined to include "the cost of replacement power." Such limitations in the contract are subject to applicable exceptions both in the contract and under law. SCE has notified MHI that it believes one or more of such exceptions now apply and that MHI's liability is not limited to $138 million, and MHI has advised SCE that it disagrees. The disagreement may ultimately become subject to dispute resolution procedures set forth in the purchase agreement, including international arbitration. SCE, on behalf of itself and the other San Onofre co-owners, has submitted five invoices to MHI totaling $139 million for steam generator repair costs incurred through February 28, 2013. MHI paid the first invoice of $45 million, while reserving its right to challenge any of the charges in the invoice. In January 2013, MHI advised SCE that it rejected a portion of the first invoice and required further documentation regarding the remainder of the invoice. SCE has recorded its share of the invoice paid as a reduction of repair and inspection costs.

San Onofre carries both property damage and outage insurance issued by Nuclear Electric Insurance Limited (“NEIL”) and has placed NEIL on notice of claims under the two policies. The NEIL policies have a number of exclusions and limitations that may reduce or eliminate coverage. As of the date of this report, SCE has filed separate proofs of loss for Unit 2 and Unit 3 under the outage policy covering the period of the outage through December 29, 2012 that total $234 million (SCE's share of which is approximately $183 million). Pursuant to these proofs of loss SCE is seeking the weekly indemnity amounts provided under the outage policy for each Unit. Because the outage is ongoing, SCE has supplemented and will continue to supplement these proofs of loss in the future. SCE has not submitted a proof of loss under the property damage policy. No amounts have been recognized in SCE's financial statements, pending NEIL's response. To the extent any costs are recovered under the outage policy, SCE expects to refund those amounts to customers through the ERRA balancing account.

The costs tracked in the memorandum account through March 31, 2013 under the CPUC's OII include approximately $728 million of SCE's authorized revenue requirement associated with operating and maintenance expenses, and depreciation and return on SCE's investment in Unit 2, Unit 3 and common plant. This amount is subject to refund depending on the outcome of the investigation.

In 2005, the CPUC authorized expenditures of approximately $525 million ($665 million based on SCE's estimate after adjustment for inflation using the Handy-Whitman Index) for SCE's 78.21% share of the costs to purchase and install the four new steam generators in Units 2 and 3 and remove and dispose of their predecessors. SCE has spent $602 million through March 31, 2013 on the steam generator replacement project. These expenditures remain subject to CPUC reasonableness review and approval.

As a result of outages associated with the steam generator inspection and repair, electric power and capacity normally provided by San Onofre are being purchased in the market by SCE . These market power costs are typically recoverable through the ERRA balancing account subject to CPUC reasonableness review, but will now be reviewed as part of the CPUC’s OII proceeding. The cost estimate required in the OII proceeding produce a market power cost estimate that differs from SCE’s prior estimates, as the OII methodology includes cost estimates during planned outage periods (such as for refueling) and estimated foregone energy sales from excess San Onofre production. Estimated market power costs calculated in accordance with the OII methodology were approximately $444 million as of March 31, 2013, net of avoided nuclear fuel costs. Such amount includes costs of approximately $50 million associated with planned outage periods. SCE believes that such costs should be excluded as they would have been incurred even had the replacement steam generators performed as expected. The CPUC will ultimately determine a final methodology for estimating market power costs as it continues its review of the issues in the OII. Future market power costs are uncertain and will be influenced by factors such as when, if, and at what output levels either of the San Onofre Units is returned to service, as well as variations in the cost of power in the market; however, such amounts may be material.

Through March 31, 2013, SCE's share of incremental inspection and repair costs totaled $109 million for both Units (not including payments made by MHI as described below), and repairs to restart Unit 2 at the reduced power levels described above were completed. The costs for Unit 2 may increase following NRC review under the CAL. Total incremental repair costs associated with returning Unit 3 to service, and returning both Units to service at originally specified capabilities safely, remain uncertain. SCE recorded its share of payments made to date by MHI ($36 million) as a reduction of incremental inspection and repair costs in 2012.

SCE believes that the actions taken and costs incurred in connection with the San Onofre replacement steam generators and outages have been prudent. Accordingly, SCE considers its operating, capital, and market power costs, recoverable through base rates and the ERRA balancing account, as offset by third party recoveries where applicable. SCE cannot provide assurance that either or both Units of San Onofre will be returned to service, that the CPUC will not disallow costs incurred or order refunds to customers of amounts collected in rates, or that SCE will be successful in recovering amounts from third parties. A delay in the restart of San Onofre Unit 2 beyond summer 2013 may impact plans for future operations of both Units. Disallowances of costs and/or refund of amounts received from customers could be material and adversely affect SCE's financial condition, results of operations and cash flows. SCE will pursue recoveries arising from available agreements, but there is no assurance that SCE will recover all of its applicable costs pursuant to these arrangements.

EME Chapter 11 Filing

On the Petition Date, EME and certain of its wholly-owned subsidiaries filed voluntary petitions for relief under Chapter 11 of the Bankruptcy Code in the Bankruptcy Court. Under the Support Agreement to which EME, Edison International and certain of EME's senior unsecured noteholders are parties, each of them has agreed to support Bankruptcy Court approval of the Settlement Transaction. EME has a customary "fiduciary out" under the Support Agreement. Moreover, the Bankruptcy Court may not approve the Settlement Transaction, or even if the Settlement Transaction is approved, it may not be consummated if certain conditions are not met. If the Settlement Transaction is not approved and consummated, Edison International may not be entitled to the benefits of the Settlement Transaction and it will remain subject to any claims of EME and the noteholders, including claims relating to or arising out of any shared services, the tax allocation agreement, and any other relationships or transactions between the companies. For further information, see Note 16.

CPUC Safety and Enforcement Division Investigations

San Gabriel Valley Windstorm Investigation

In November 2011, a windstorm resulted in significant damage to SCE’s electric system and service outages for SCE customers primarily in the San Gabriel Valley. The CPUC directed its Safety and Enforcement Division (“SED”) to conduct an investigation focused on the cause of the outages, SCE’s service restoration effort, and SCE’s customer communications during the outages. The SED issued its final report on January 11, 2013. The report asserts that SCE and others with whom SCE shares utility poles violated certain CPUC safety rules applicable to overhead line construction, maintenance and operation, which may have caused the failures of affected poles and supporting cables. The report also concludes that SCE’s restoration time was not adequate and makes other assertions. Additionally, the report contends that SCE violated CPUC rules by failing to preserve evidence relevant to the investigation when it did not retain damaged poles that were replaced following the windstorm. If the CPUC issues an OII regarding this matter and SCE is found to have violated any CPUC rules, it could face penalties. SCE is unable to estimate a possible loss or range of loss associated with any penalties that may be imposed by the CPUC on SCE.

The final decision in SCE’s 2012 GRC directed SCE to, among other things, make an assessment of a representative sampling of its poles to determine their conformance with current legal standards and report by July 31, 2013 on the results of this assessment. The cost of any large scale review of poles or other equipment for safety compliance, as well as any remediation measures required to assure compliance, could be significant.

Malibu Fire Order Instituting Investigation

Following a 2007 wildfire in Malibu, California, the CPUC issued an OII to determine if any statutes, CPUC general orders, rules or regulations were violated by SCE or telecomm providers (“OII Respondents”) that shared the use of three failed power poles in the wildfire area. The SED has alleged, among other things, that the poles were overloaded, that the OII Respondents violated the CPUC's rules governing the design, construction and inspection of poles, and that SCE failed to preserve evidence relevant to the investigation and misled the CPUC during its investigation of the fire. In October 2011, the SED proposed that the OII Respondents be assessed penalties of approximately $99 million, with SCE being allocated approximately $50 million of the total. SCE has denied the allegations and believes the proposed penalties are excessive. In September 2012, the CPUC approved a partial settlement between the SED and three telecomm providers. The partial settlement did not resolve any of the claims against SCE or the remaining telecomm provider. In February 2013, SCE was informed that the remaining telecomm provider had reached an agreement to settle with the SED, which remains subject to final documentation and CPUC approval.

Four Corners New Source Review Litigation

In October 2011, four private environmental organizations filed a CAA citizen lawsuit against the co-owners of Four Corners. The complaint alleges that certain work performed at the Four Corners generating units 4 and 5, over the approximate periods of 1985 – 1986 and 2007 – 2010, constituted plant “major modifications” and the plant's failure to obtain permits and install best available control technology ("BACT") violated the PSD requirements and the New Source Performance Standards of the CAA. The complaint also alleges subsequent and continuing violations of BACT air emissions limits. The lawsuit seeks injunctive and declaratory relief, civil penalties, including a mitigation project and litigation costs. In November 2012, the parties requested a stay of the litigation to allow for settlement discussion, and the matter is currently stayed to April 2013. In November 2010, SCE entered into an agreement to sell its ownership interest in generating units 4 and 5 to APS. The sale remains contingent upon APS obtaining a long-term fuel supply agreement for the plant. As of January 2013, the sale agreement became terminable by either party, but as of the date of this report, the agreement has not been terminated. Under the agreement SCE would remain responsible for its pro rata share of certain environmental liabilities, including penalties arising from environmental violations prior to the sale. SCE is unable to estimate a possible loss or range of loss associated with this matter.

Environmental Remediation

Edison International records its environmental remediation liabilities when site assessments and/or remedial actions are probable and a range of reasonably likely cleanup costs can be estimated. Edison International reviews its sites and measures the liability quarterly, by assessing a range of reasonably likely costs for each identified site using currently available information, including existing technology, presently enacted laws and regulations, experience gained at similar sites, and the probable level of involvement and financial condition of other potentially responsible parties. These estimates include costs for site investigations, remediation, operation and maintenance, monitoring and site closure. Unless there is a single probable amount, Edison International records the lower end of this reasonably likely range of costs (reflected in "Other long-term liabilities") at undiscounted amounts as timing of cash flows is uncertain.

At March 31, 2013, Edison International's recorded estimated minimum liability to remediate its 23 identified material sites (sites in which the upper end of the range of the costs is at least $1 million) at SCE was $124 million, including $91 million related to San Onofre. In addition to its identified material sites, SCE also has 35 immaterial sites for which the total minimum recorded liability was $3 million. Of the $127 million total environmental remediation liability for SCE, $123 million has been recorded as a regulatory asset. SCE expects to recover $31 million through an incentive mechanism that allows SCE to recover 90% of its environmental remediation costs at certain sites (SCE may request to include additional sites) and $92 million through a mechanism that allows SCE to recover 100% of the costs incurred at certain sites through customer rates. Edison International's identified sites include several sites for which there is a lack of currently available information, including the nature and magnitude of contamination, and the extent, if any, that Edison International may be held responsible for contributing to any costs incurred for remediating these sites. Thus, no reasonable estimate of cleanup costs can be made for these sites.

The ultimate costs to clean up Edison International's identified sites may vary from its recorded liability due to numerous uncertainties inherent in the estimation process, such as: the extent and nature of contamination; the scarcity of reliable data for identified sites; the varying costs of alternative cleanup methods; developments resulting from investigatory studies; the possibility of identifying additional sites; and the time periods over which site remediation is expected to occur. Edison International believes that, due to these uncertainties, it is reasonably possible that cleanup costs at the identified material sites and immaterial sites could exceed its recorded liability by up to $180 million and $6 million, respectively, all of which is related to SCE. The upper limit of this range of costs was estimated using assumptions least favorable to Edison International among a range of reasonably possible outcomes.

SCE expects to clean up and mitigate its identified sites over a period of up to 30 years. Remediation costs for 2013 and in each of the next four years are expected to range from $6 million to $28 million. Costs incurred for both the three months ended March 31, 2013 and 2012 was $2 million.

Based upon the CPUC's regulatory treatment of environmental remediation costs incurred at SCE, Edison International believes that costs ultimately recorded will not materially affect its results of operations, financial position or cash flows. There can be no assurance, however, that future developments, including additional information about existing sites or the identification of new sites, will not require material revisions to estimates.

Nuclear Insurance

Federal law limits public liability claims from a nuclear incident to the amount of available financial protection, which is currently approximately $12.6 billion. SCE and other owners of San Onofre and Palo Verde have purchased the maximum private primary insurance available ($375 million). The balance is covered by a loss sharing program among nuclear reactor licensees. If a nuclear incident at any licensed reactor in the United States results in claims and/or costs which exceed the primary insurance at that plant site, all nuclear reactor licensees could be required to contribute their share of the liability in the form of a deferred premium.

Based on its ownership interests, SCE could be required to pay a maximum of approximately $235 million per nuclear incident. However, it would have to pay no more than approximately $35 million per incident in any one year. If the public liability limit above is insufficient, federal law contemplates that additional funds may be appropriated by Congress. This could include an additional assessment on all licensed reactor operators as a measure for raising further federal revenue.

NEIL, a mutual insurance company owned by entities with nuclear facilities, issues primary property damage, decontamination and excess property damage and accidental outage insurance policies. At San Onofre and Palo Verde, property damage insurance covers losses up to $500 million, including decontamination costs. Decontamination liability and excess property damage coverage exceeding the primary $500 million also has been purchased in amounts greater than the federal requirement of a minimum of approximately $1.1 billion. Property damage insurance also covers damages caused by acts of terrorism up to specified limits. Additional outage insurance covers part of replacement power expenses during an accident-related nuclear unit outage.

If losses at any nuclear facility covered by the arrangement were to exceed the accumulated funds for these insurance programs, SCE could be assessed retrospective premium adjustments of up to approximately $52 million per year. Insurance premiums are charged to operating expense.

Wildfire Insurance

Severe wildfires in California have given rise to large damage claims against California utilities for fire-related losses alleged to be the result of the failure of electric and other utility equipment. Invoking a California Court of Appeal decision, plaintiffs pursuing these claims have relied on the doctrine of inverse condemnation, which can impose strict liability (including liability for a claimant's attorneys' fees) for property damage. On September 15, 2012, SCE's parent, Edison International, renewed its insurance coverage, which included coverage for SCE's wildfire liabilities up to a $550 million limit (with a self-insured retention of $10 million per wildfire occurrence). Various coverage limitations within the policies that make up the insurance coverage could result in additional self-insured costs in the event of multiple wildfire occurrences during the policy period (September 15, 2012 to August 31, 2013). SCE may experience coverage reductions and/or increased insurance costs in future years. No assurance can be given that future losses will not exceed the limits of SCE's insurance coverage.

Spent Nuclear Fuel

Under federal law, the Department of Energy ("DOE") is responsible for the selection and construction of a facility for the permanent disposal of spent nuclear fuel and high-level radioactive waste. The DOE did not meet its contractual obligation to begin acceptance of spent nuclear fuel by January 31, 1998. Extended delays by the DOE have led to the construction of costly alternatives and associated siting and environmental issues. Currently, both San Onofre and Palo Verde have interim storage for spent nuclear fuel on site sufficient for the current license period.

In June 2010, the United States Court of Federal Claims issued a decision granting SCE and the San Onofre co-owners damages of approximately $142 million to recover costs incurred through December 31, 2005 for the DOE's failure to meet its obligation to begin accepting spent nuclear fuel from San Onofre. SCE received payment from the federal government in the amount of the damage award in November 2011. SCE has returned to the San Onofre co-owners their respective share of the damage award paid. SCE, as operating agent, filed a lawsuit on behalf of the San Onofre owners against the DOE in the Court of Federal Claims in December 2011 seeking damages of approximately $98 million for the period from January 1, 2006 to December 31, 2010 for the DOE's failure to meet its obligation to begin accepting spent nuclear fuel. Additional legal action would be necessary to recover damages incurred after December 31, 2010. Any damages recovered by SCE are subject to CPUC review as to how these amounts would be distributed among customers, shareholders, or to offset fuel decommissioning or storage costs.