Customers Accumulated other comprehensive loss Less - Accumulated provision for depreciation Other paid-in capital Property additions Property additions Deferred purchased power and other costs Gain on asset sales Accumulated provision for uncollectible accounts - customers Nuclear fuel and lease amortization Amortization of regulatory assets Asset retirement obligations CONSOLIDATED BALANCE SHEETS Cash and cash equivalents Cash and cash equivalents at beginning of period Cash and cash equivalents at end of year Net controlled disbursement activity Accrued compensation and retirement benefits Accrued taxes Increase (Decrease) in Accrued Income Taxes Payable Accrued interest (Increase) Decrease in Inventories Materials and supplies Decrease (increase) in operating assets- Increase (decrease) in operating liabilities- Prepayments and other current assets Increase (Decrease) in Prepaid Expense Accounts payable Increase (Decrease) in Accounts Payable, Trade COMMITMENTS, GUARANTEES AND CONTINGENCIES Power purchase contract asset Common stock - shares authorized Common stock - shares outstanding Ending Balance (in shares) Beginning Balance (in shares) Common stock COMPREHENSIVE INCOME ATTRIBUTABLE TO PARENT COMPREHENSIVE INCOME ATTRIBUTABLE TO FIRSTENERGY CORP. Construction work in progress Fuel Purchased power CURRENT LIABILITIES: Total current liabilities Liabilities, Current Currently payable long-term debt Long-term debt and other long-term obligations Nuclear plant decommissioning trusts DERIVATIVE INSTRUMENTS DILUTED EARNINGS PER SHARE OF COMMON STOCK Stock-based compensation Investment impairment CONSOLIDATED STATEMENTS OF INCOME INCOME TAXES Income Tax Disclosure [Text Block] Materials and supplies, at average cost INVESTMENTS: LIABILITIES AND CAPITALIZATION Total liabilities and capitalization Total liabilities and capitalization Total investments Total investments Investments in lease obligation bonds Noncontrolling interest CASH FLOWS FROM FINANCING ACTIVITIES: Net cash provided from (used in ) financing activities Net cash provided from (used for) financing activities CASH FLOWS FROM INVESTING ACTIVITIES: Net cash provided from (used in ) investing activity Net cash used for investing activities CASH FLOWS FROM OPERATING ACTIVITIES: Net cash provided from (used in) operating activities Net cash provided from operating activities EARNINGS AVAILABLE TO PARENT Earnings available to FirstEnergy Corp. EARNINGS AVAILABLE TO FIRSTENERGY CORP. Net change in cash and cash equivalents Net change in cash and cash equivalents NEW ACCOUNTING STANDARDS AND INTERPRETATIONS Interest expense Total deferred charges and other assets Total deferred charges and other assets NONCURRENT LIABILITIES: Total noncurrent liabilities Total noncurrent liabilities OPERATING INCOME OPERATING INCOME REVENUES: Total revenues Total revenues ORGANIZATION AND BASIS OF PRESENTATION Other Increase (Decrease) in Other Operating Assets and Liabilities, Net Other comprehensive income (loss) Other comprehensive income Pension and other postretirement benefits Unrealized gain on derivative hedges Other comprehensive income (loss), net of tax Other comprehensive income, net of tax Income tax expense related to other comprehensive income Income tax expense (benefit) related to other comprehensive income Change in unrealized gain on available-for-sale securities Prepayments and Other Other Other Payments for (Proceeds from) Other Investing Activities Other Other Other Long-term Investments Other Proceeds from (Payments for) Other Financing Activities Other Other Receivables Common stock dividend payments Common stock dividend payments PENSION AND OTHER POSTRETIREMENT BENEFITS Prepaid taxes Long-term debt Proceeds from Issuance of Long-term Deb Sales of investment securities held in trusts Proceeds from asset sales Short-term borrowings, net In service Total property, plant and equipment Total property, plant and equipment REGULATORY MATTERS Purchases of investment securities held in trusts Purchases of investment securities held in trusts Cash investments Cash investments Receivables- Regulatory assets Long-term debt Repayments of Long-term Debt Retained earnings Electric utilities Unregulated businesses Deferred gain on sale and leaseback transaction SUPPLEMENTAL GUARANTOR INFORMATION SEGMENT INFORMATION Short-term borrowings CONSOLIDATED STATEMENTS OF CASH FLOWS CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME Common stockholders' equity- CURRENT ASSETS: Total current assets Assets, Current VARIABLE INTEREST ENTITIES WEIGHTED AVERAGE NUMBER OF DILUTED SHARES OUTSTANDING WEIGHTED AVERAGE NUMBER OF BASIC SHARES OUTSTANDING PROPERTY, PLANT AND EQUIPMENT: Total assets Total assets Investment income (loss), net Other Other Liabilities, Current Other Other Liabilities, Noncurrent DIVIDENDS DECLARED PER SHARE OF COMMON STOCK Accumulated deferred income taxes ASSETS Assets [Abstract] FAIR VALUE OF FINANCIAL INSTRUMENTS BASIC EARNINGS PER SHARE OF COMMON STOCK Provision for depreciation Electric service prepayment programs Other Other Assets, Noncurrent Other operating expenses INCOME BEFORE INCOME TAXES INCOME BEFORE INCOME TAXES Deferred income taxes and investment tax credits, net Common stock - par value Total common stockholders' equity Total common stockholders' equity INCOME TAXES Capitalized interest Receivables Lease market valuation liability Goodwill EXPENSES: Total expenses Total expenses EARNINGS PER SHARE NET INCOME NET INCOME COMPREHENSIVE LOSS ATTRIBUTABLE TO NONCONTROLLING INTEREST Accrued taxes Accrued Income Taxes, Current General taxes CAPITALIZATION: Total equity Beginning Balance Ending Balance Total equity Accounts payable Retirement benefits COMMITMENTS, GUARANTEES AND CONTINGENCIES (Note X) Adjustments to reconcile net income to net cash from operating activities- Net Plant Excluding Construction Work In Progress Period end amount of total net PPE Total in service, net of accumulated depreciation Total capitalization total stockholders' equity, term debt and other long-term obligations. Total capitalization Power purchase contract liability Total obligations incurred as part of normal operations that is expected to be repaid beyond the following twelve months or one business cycle. Contract (Loss) Liabilities Current period electric expenses of a regulated entity which are reclassified as capitalized electric costs and are expected to be recoverable through rate adjustments. Deferral of regulatory assets Deferral of new regulatory assets Deferral of new regulatory assets The total of other income and expense items resulting from secondary business-related activities, excluding those considered part of the normal operations of the business that have not been previously categorized. Total other expense Total other expense Deferred rents and lease market valuation liability Cash collateral paid Cash received from or paid to suppliers based on deposits required for hedging activities. Cash Collateral, Net The portion of net income (loss) attributable to the noncontrolling interest (if any) deducted in order to derive the portion attributable to the parent. Net Income (Loss) Attributable to Noncontrolling Interest, Total COMPREHENSIVE INCOME ATTRIBUTABLE TO NONCONTROLLING INTEREST Noncontrolling interest loss Net Income Loss Attributable To Noncontrolling Interest Income Statement Less: Noncontrolling interest income (loss) OTHER INCOME (EXPENSE): Other Income (Expense) [Abstract] DEFERRED CHARGES AND OTHER ASSETS: Deferred Charges and Other Assets [Abstract] Notes to Financial Statements [Abstract] Accumulated provision for uncollectible accounts - other Document Type Document Period End Date Amendment Flag Amendment Description Entity Registrant Name Entity Central Index Key Current Fiscal Year End Date Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Current Reporting Status Entity Filer Category Entity Public Float Entity Common Stock Shares Outstanding New Financing [Abstract] New Financing- Redemptions and Repayments [Abstract] Redemptions and Repayments- Short-term borrowings, net Repayments of Short-term Debt Short-term borrowings, net Schedule of Goodwill [Text Block] GOODWILL SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES LEASES DIVESTITURES CAPITALIZATION ASSET RETIREMENT OBLIGATIONS SHORT-TERM BORROWINGS AND BANK LINES OF CREDIT TRANSACTIONS WITH AFFILIATED COMPANIES SUMMARY OF QUARTERLY FINANCIAL DATA (UNAUDITED) Document Information [Text Block] Entity [Text Block] SUPPLEMENTAL CASH FLOW INFORMATION: Cash Paid During Year [Abstract] Cash Paid During the Year- Interest (net of amounts capitalized) Income taxes SUBSEQUENT EVENT STOCK-BASED COMPENSATION PLANS CONSOLIDATED VALUATION AND QUALIFYING ACCOUNTS Document Fiscal Year Focus Document Fiscal Period Focus COMPREHENSIVE INCOME COMPREHENSIVE INCOME OTHER COMPREHENSIVE INCOME: Gain Loss On Derivatives The gains and losses from increase (decrease) in fair value of derivatives included in earnings. Commodity derivative transactions, net Customer Intangibles Customer Intangibles INTANGIBLE ASSETS PROPOSED MERGER WITH ALLEGHENY ENERGY, INC.