Accounts Receivable, Net, Current, Total Accounts receivable-trade Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning Balance Accumulated other comprehensive income Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Beginning Balance Less accumulated depreciation and amortization Equity Method Investment, Dividends or Distributions Distributions from unconsolidated affiliates Due from Affiliate, Current Receivables from affiliates Cash and Cash Equivalents, at Carrying Value, Beginning Balance Cash and cash equivalents Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Increase (Decrease) in Commodity Contract Assets and Liabilities (Increase) decrease in derivative assets and liabilities Increase (Decrease) in Interest Payable, Net Increase in interest payable Increase (Decrease) in Inventories, Total (Increase) decrease in inventory Increase (Decrease) in Prepaid, Deferred Expense and Other Assets, Total Decrease (increase) in prepaid expenses and other Increase (Decrease) in Receivables, Total Increase in accounts receivables Changes in operating assets and liabilities: Increase (Decrease) in Margin Deposits Outstanding (Increase) decrease in margin and collateral deposits Commitments and Contingencies Disclosure [Text Block] Commitments and Contingencies Common Stock, Shares Authorized Common stock, shares authorized Common Stock, Shares, Outstanding, Beginning Balance Common stock, shares outstanding Common Stock, Value, Issued, Beginning Balance Common stock, par value $0.01 per share; 10,000 shares authorized; 100 shares issued and outstanding as of December 31, 2009 and 2008 Comprehensive Income, Net of Tax, Attributable to Parent, Total Comprehensive Income Attributable to EME Common Shareholders Comprehensive Income Note [Text Block] Accumulated Other Comprehensive Income Fuel Costs Fuel Current Liabilities Liabilities, Current, Total Total current liabilities Derivative Assets, Current Derivative assets Derivative Assets, Noncurrent Long-term derivative assets Derivative Instruments and Hedging Activities Disclosure [Text Block] Derivative Instruments and Risk Management Derivative Liabilities, Current Derivative liabilities Derivative Liabilities, Noncurrent Long-term derivative liabilities Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Divestitures Income (Loss) from Equity Method Investments, Total Equity in income from unconsolidated affiliates General and Administrative Expense, Total Administrative and general Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest, Total Income (loss) from operations of discontinued subsidiaries, net of tax (Note 7) (Income) loss from discontinued operations Income (loss) from discontinued operations, net of tax Income Tax Disclosure [Text Block] Income Taxes Increase (Decrease) in Other Operating Assets Other operating-assets Increase (Decrease) in Restricted Cash, Total Decrease in restricted deposits Interest Expense, Total Interest expense Other Interest and Dividend Income Dividend income Inventory, Net, Total Inventory Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures, Total Investments in Unconsolidated Affiliates Liabilities and Shareholder's Equity Liabilities and Stockholders' Equity, Total Total Liabilities and Equity Liabilities, Total Total Liabilities Long-term Debt, Current Maturities, Total Current maturities of long-term obligations Long-term Debt, Excluding Current Maturities, Total Long-term obligations net of current maturities Held-to-maturity Securities, Current Short-term investments Noncontrolling Interest Disclosure [Text Block] Noncontrolling Interests Stockholders' Equity Attributable to Noncontrolling Interest, Beginning Balance Noncontrolling Interests Net Cash Provided by (Used in) Operating Activities, Continuing Operations, Total Operating cash flow from continuing operations Cash Flows From Financing Activities Net Cash Provided by (Used in) Financing Activities, Total Net cash provided by (used in) financing activities Cash Flows From Investing Activities Net Cash Provided by (Used in) Investing Activities, Total Net cash used in investing activities Cash Flows From Operating Activities Net Cash Provided by (Used in) Operating Activities, Total Net cash provided by operating activities Net Income (Loss) Attributable to Parent, Total Net Income Attributable to EME Common Shareholders Cash and Cash Equivalents, Period Increase (Decrease), Total Net increase (decrease) in cash and cash equivalents Other Income (Expense) Nonoperating Income (Expense), Total Total other income (expense) Operating Income (Loss), Total Operating income Unrealized gains (losses) on derivatives qualified as cash flow hedges: Other comprehensive income (loss), net of tax Other Comprehensive Income (Loss), Net of Tax, Total Other comprehensive income (loss) Other comprehensive income (loss) Other Comprehensive Income, Reclassification Adjustment on Derivatives Included in Net Income, Tax Reclassification adjustments included in net income, income tax expense (benefit) Other Comprehensive Income, Reclassification Adjustment on Derivatives Included in Net Income, Net of Tax Reclassification adjustments included in net income, net of income tax expense (benefit) of $124, $(58) and $(45) for 2009, 2008 and 2007, respectively Other Comprehensive Income, Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax Unrealized holding gains (losses) arising during period, net of income tax expense (benefit) of $36, $138 and $(160) for 2009, 2008 and 2007, respectively Other Comprehensive Income, Unrealized Gain (Loss) on Derivatives Arising During Period, Tax Unrealized holding gains (losses) arising during period, income tax expense (benefit) Payments for (Proceeds from) Other Investing Activities Investments in other assets Other Nonoperating Income (Expense), Total Other income (expense), net Proceeds from Issuance of Long-term Debt, Total Borrowings on long-term debt Proceeds from Maturities, Prepayments and Calls of Held-to-maturity Securities Maturities of short-term investments Property, Plant and Equipment, Gross, Beginning Balance Property, Plant and Equipment Property, Plant and Equipment, Net, Beginning Balance Net property, plant and equipment Payments to Acquire Interest in Subsidiaries and Affiliates, Total Purchase of interest of acquired companies Payments to Acquire Property, Plant, and Equipment, Total Capital expenditures Repayments of Long-term Debt, Total Payments on long-term debt agreements Restricted cash Retained Earnings (Accumulated Deficit), Beginning Balance Retained earnings Electrical Generation Revenue Operating Revenues Sale Leaseback Transaction, Rent Expense Plant operating leases Significant Accounting Policies [Text Block] Summary of Significant Accounting Policies Current Assets Assets, Current, Total Total current assets Schedule of Variable Interest Entities [Text Block] Variable Interest Entities Assets, Total Total Assets Investment Income, Interest Interest income Other Assets Deferred Finance Costs, Noncurrent, Net, Total Deferred financing costs Other Liabilities, Noncurrent, Total Other long-term liabilities Assets Fair Value Disclosures [Text Block] Fair Value Measurements Cash Provided by (Used in) Operating Activities, Discontinued Operations Operating cash flow from discontinued operations Cash Flow, Supplemental Disclosures [Text Block] Supplemental Cash Flows Information Excess Tax Benefit from Share-based Compensation, Financing Activities Excess tax benefits related to stock-based awards Common Stock, Shares, Issued, Total Common stock, shares issued Other Cost and Expense, Operating Plant operations Other Assets, Noncurrent, Total Other long-term assets Increase (Decrease) in Other Operating Liabilities Other operating-liabilities Deferred Revenue and Credits, Noncurrent, Total Deferred revenues Deferred Income Taxes and Tax Credits, Total Deferred taxes and tax credits Common Stock, Par or Stated Value Per Share Common stock, par value (in dollars per share) Stockholders' Equity Attributable to Parent, Beginning Balance Total EME common shareholder's equity Income Tax Expense (Benefit), Total Provision for income taxes Good Faith and Margin Deposits with Broker-Dealers Margin and collateral deposits Gain (Loss) on Contract Termination Gain on buyout of contract, loss on termination of contract, asset write-down and other charges and credits, net (Notes 1, 5 and 13) Operating Expenses Costs and Expenses, Total Total operating expenses Document and Entity Information Document and Entity Information [Abstract] Prepaid Expenses and Other Current Assets Sum of the amounts paid in advance for capitalized costs that will be expensed with the passage of time or the occurrence of a triggering event, and will be charged against earnings within one year or the normal operating cycle, if longer, combined with the aggregate carrying amount, as of the balance sheet date, of current assets not separately disclosed in the balance sheet due to materiality considerations. Current assets are expected to be realized or consumed within one year (or the normal operating cycle, if longer). Prepaid expenses and other Total Other Assets, Noncurrent Sum of the carrying amounts as of the balance sheet date of all other assets that are expected to be realized in cash, sold or consumed after one year or beyond the normal operating cycle, if longer. Total other assets Rent Payments In Excess of Levelized Rent Expense Under Plant Operating Leases Represents prepaid rent, which is the excess of cash rent payments over the amount of rent expense levelized over the term of each plant operating lease. To the extent that cash rent payments are less than the amount levelized, prepaid rent is reduced. Rent payments in excess of levelized rent expense under plant operating leases Income from Continuing Operations before Income Taxes Sum of operating profit and non operating income (expense) before income taxes and noncontrolling interest. Income from continuing operations before income taxes Increase in Rent Payments in Excess of Levelized Rent Expense The net change during the reporting period in the aggregate value of rent payments in excess of levelized rent expense under plant operating leases. Increase in rent payments in excess of levelized rent expense Increase (Decrease) in Accounts Payable and Other Current Liabilities The net change during the reporting period in the aggregate amount of obligations and expenses incurred but not paid, excluding interest payable. (Decrease) increase in accounts payable and other current liabilities-EXTENSION (OLD) Payments to Affiliates Related to Stock-Based Awards Represents cash used by parent company to settle stock options exercised by employees of affiliates. Payments to affiliates related to stock-based awards Proceeds from Return of Capital, Loan Repayments, and Sale of Assets Proceeds from return of capital and loan repayments (includes distributions received from unconsolidated subsidiaries that constitute a return of investment or loan repayment) and sale of assets (cash inflow from sale of other property, plant and equipment used to produce goods or deliver services, and not otherwise defined in taxonomy) Proceeds from return of capital and loan repayments and sale of assets NOTES TO CONSOLIDATED FINANCIAL STATEMENTS Notes to Financial Statements [Abstract] Depreciation and Amortization, Cash Flow Impact The cash flow impact of the current period expense charged against earnings on long-lived, physical assets used in the normal conduct of business and not intended for resale to allocate or recognize the cost of assets over their useful lives; or to record the reduction in book value of an intangible asset over the benefit period of such asset. Examples include buildings, production equipment and customer lists, deferred financing costs, and accretion of discounted liabilities. Depreciation and amortization Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Total Net Income Net Income Net income (loss) Net income Net Income (Loss) Attributable to Noncontrolling Interest, Total Net Loss Attributable to Noncontrolling Interests Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest, Total Income from continuing operations, net Income From Continuing Operations Comprehensive Income, Net of Tax, Including Portion Attributable to Noncontrolling Interest, Total Comprehensive Income Comprehensive Income, Net of Tax, Attributable to Noncontrolling Interest, Total Comprehensive Loss Attributable to Noncontrolling Interests Equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance Total Equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Beginning Balance Ending Balance Commitments and Contingencies Commitments and Contingencies (Notes 3, 10 and 13) Cash dividends to parent Dividends, Common Stock, Cash Adjustments to reconcile income to net cash provided by operating activities: Accounts Payable, Current Accounts payable Accrued Liabilities, Current Accrued liabilities Due to Affiliate, Current Payables to affiliates Interest Payable, Current Interest payable Pension and postretirement benefits other than pensions: Restricted Cash and Cash Equivalents, Current Restricted cash CONSOLIDATED STATEMENTS OF INCOME Statement [Line Items] CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME CONSOLIDATED BALANCE SHEETS Restricted Cash and Investments, Noncurrent Restricted deposits CONSOLIDATED STATEMENTS OF CASH FLOWS Income (Loss) from Equity Method Investments, Cash Flow Impact Equity in income from unconsolidated affiliates This item represents the entity's proportionate share for the period of the undistributed net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. Such amount typically reflects adjustments similar to those made in preparing consolidated statements, including adjustments to eliminate intercompany gains and losses and to amortize, if appropriate, any difference between cost and underlying equity in net assets of the investee at the date of investment. Proceeds from sale of membership interest Proceeds From Sale Of Membership Interest Proceeds From Sale Of Membership Interest Restructuring and Related Activities Disclosure [Text Block] Restructuring Costs Schedule of Business Acquisitions, by Acquisition [Text Block] Property, Plant and Equipment [Text Block] Property, Plant and Equipment Related Party Transactions Disclosure [Text Block] Related-Party Transactions Quarterly Financial Information [Text Block] Quarterly Financial Data (unaudited) Payments of Dividends, Noncontrolling Interest Cash dividends to noncontrolling interests Proceeds from Noncontrolling Interests Cash contributions from noncontrolling interests Increase (Decrease) in Restricted Cash for Operating Activities Increase in restricted cash Other Comprehensive Income, Reclassification of Defined Benefit Plan's Net (Gain) Loss Recognized in Net Periodic Benefit Cost, Net of Tax Amortization of net loss and prior service adjustment included in expense, net of tax Purchase of short-term investments Payments to Acquire Held-to-maturity Securities Statement [Table] Schedule of Subsequent Events [Text Block] Subsequent Events Gains (Losses) on Extinguishment of Debt Loss on early extinguishment of debt Loss on early extinguishment of debt Amounts Attributable to EME Common Shareholders Income from continuing operations, net of tax Income (Loss) from Continuing Operations Attributable to Parent Prior service adjustment, net of tax Other Comprehensive Income, Defined Benefit Plan, Net Prior Service Costs (Credit) Arising During Period, Net of Tax Net gain (loss) adjustment, net of tax expense (benefit) of $6, $(26) and $4 for 2009, 2008 and 2007, respectively Other Comprehensive Income, Defined Benefit Plan's Net Unamortized (Gain) Loss Arising During Period, Net of Tax Net gain (loss) adjustment, tax expense (benefit) Other Comprehensive Income, Defined Benefit Plan's Net Unamortized Gain (Loss) Arising During Period, Tax Cash contribution from parent Proceeds from Contributions from Parent Cash dividends to parent Payments of Dividends, Common Stock Acquisitions and Schedule of Variable Interest Entities [Text Block] Acquisitions and Variable Interest Entities Description of a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities. This element may be used as a single block of text to encapsulate the entire disclosure (including data and tables) regarding business combinations, including leverage buyout transactions (as applicable). This disclosure also includes disclosures of variable interest entities (VIE), including, but not limited to the nature, purpose, size, and activities of the VIE, the carrying amount and classification of consolidated assets that are collateral for the VIE's obligations, lack of recourse if creditors (or beneficial interest holders) of a consolidated VIE have no recourse to the general credit of the primary beneficiary. An enterprise that holds a significant variable interest in a VIE but is not the primary beneficiary may disclose the nature of its involvement with the VIE and when that involvement began, the nature, purpose, size, and activities of the VIE and the enterprise's maximum exposure to loss as a result of its involvement with the VIE. Adjustments to Additional Paid in Capital, Tax Effect from Share-based Compensation Excess tax benefits related to stock-option exercises Noncontrolling Interest, Increase from Stock Issuance or Sale of Parent Equity Interest Sale of membership interest in noncontrolling interests Stockholders' Equity, Period Increase (Decrease) Cumulative Effect of Initial Adoption of FIN 48 Impact of accounting for uncertainty in income taxes Payments to Parent for Stock Purchases Related to Stock-Based Compensation Payments to Edison International for stock purchases related to stock-based compensation Represents adjustments to retained earnings due to payments made to parent for stock purchases, related to stock-based compensation. Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Cash distributions to noncontrolling interests and other CONSOLIDATED STATEMENTS OF TOTAL EQUITY Statement, Equity Components [Axis] Equity Component [Domain] EME Shareholder's Equity Common Stock Additional Paid-in Capital Retained Earnings (Accumulated Deficit) Accumulated Other Comprehensive Income (Loss) Non-controlling Interests Increase (Decrease) in Stockholders' Equity Premium Paid on Extinguishment of Debt and Financing Costs Premium paid on extinguishment of debt and financing costs Amount represents the difference between the fair value of the payments made and the carrying amount of the debt at the time of its extinguishment, and the write-off of amounts previously capitalized as debt issuance cost in an extinguishment of debt. Margin and Collateral Deposits With Broker Dealers, Noncurrent Carrying value of amount deposited with counterparties and brokers as credit support under energy contracts, that are expected to be returned or applied towards payment after one year or beyond the normal operating cycle, if longer. Long-term margin and collateral deposits Proceeds from Other Minority Holders The cash inflow contributed by other noncontrolling interests that purchase additional shares or otherwise increase their ownership stake in a subsidiary of the entity. Cash contribution from minority shareholders Stockholders Equity Other Other stock transactions, net The amount contributed by noncontrolling shareholders. Cash Contributions from Noncontrolling Interests Cash contributions from noncontrolling interests Equity Method Investments Disclosure [Text Block] Debt Disclosure [Text Block] Financial Instruments Gain on buyout of contract, loss on termination of contract, asset write-down and other charges and credits Gain (Loss) on Contract Termination, Asset Impairment, and Other Charges Credits, Net This element represents the income received from or payment made to a third party in connection with the termination of a contract between the parties. The termination may be due to many causes including early termination of a lease by a lessee, a breach of contract by one or the other party, a failure to perform. This element also includes charges against earnings resulting from the write down of long lived assets other than goodwill due to the difference between the carrying value and lower fair value, and various other charges and credits not specifically identified in the taxonomy. Investments in Unconsolidated Affiliates Investments in Unconsolidated Affiliates [Text Block] This element may be used as a single block of text to include the entire equity and cost method investments disclosure, including data and tables. Compensation and Benefit Plans Compensation and Benefit Plans Disclosure [Text Block] Description containing the entire pension and other postretirement benefits disclosure as a single block of text. Also includes disclosure of compensation-related costs for share-based compensation which may include disclosure of policies, compensation plan details, allocation of stock compensation, incentive distributions, share-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details. Depreciation, Depletion and Amortization Depreciation and amortization Deferred Tax Assets (Liabilities), Net, Current Deferred taxes Deferred Tax Assets (Liabilities), Net, Noncurrent Deferred taxes and tax credits Additional Paid in Capital, Common Stock Additional paid-in capital Increase (Decrease) in Accounts Payable and Accrued Liabilities (Decrease) increase in accounts payable and other current liabilities Schedule I Condensed Financial Information of Parent [Abstract] SCHEDULE I CONDENSED FINANCIAL INFORMATION OF PARENT Condensed Financial Information of Parent Company Only Disclosure [Text Block] SCHEDULE I CONDENSED FINANCIAL INFORMATION OF PARENT SCHEDULE II VALUATION AND QUALIFYING ACCOUNTS Valuation and Qualifying Accounts [Abstract] Schedule of Valuation and Qualifying Accounts Disclosure [Text Block] SCHEDULE II VALUATION AND QUALIFYING ACCOUNTS