Document and Entity Information [Abstract] Document And Entity Information Statement [Table] Legal Entity [Axis] Entity [Domain] Consolidated Edison Co Of New York Inc [Member] Consolidated Edison Co Of New York Inc [Member] Statement [Line Items] Document Type Amendment Flag Document Period End Date Document Fiscal Year Focus Document Fiscal Period Focus Trading Symbol Entity Registrant Name Entity Central Index Key Current Fiscal Year End Date Entity Filer Category Entity Common Stock, Shares Outstanding Consolidated Income Statement CECONY [Member] CECONY [Member] OPERATING REVENUES Electric Revenue Electric Revenue, Total Electric Gas Domestic Regulated Revenue Gas Revenue Steam Products and Services Steam Non-utility TOTAL OPERATING REVENUES TOTAL OPERATING REVENUES OPERATING EXPENSES Purchased power Fuel Gas purchased for resale Other operations and maintenance Depreciation, Depletion and Amortization, Nonproduction Depreciation, Depletion and Amortization, Nonproduction, Total Depreciation and amortization Taxes, other than income taxes Taxes, Miscellaneous, Total TOTAL OPERATING EXPENSES TOTAL OPERATING EXPENSES OPERATING INCOME Operating income OPERATING INCOME OTHER INCOME (DEDUCTIONS) Investment and other income Investment Income, Net, Total Allowance for equity funds used during construction Other deductions Other deductions Other Nonoperating Expense, Total TOTAL OTHER INCOME (DEDUCTIONS) TOTAL OTHER INCOME (DEDUCTIONS) Other income (deductions), net of taxes Income before interest income, interest expense and income taxes Income Before Interest Income Interest Expense And Income Taxes INCOME BEFORE INTEREST AND INCOME TAX EXPENSE INTEREST EXPENSE Interest on long-term debt Interest Expense, Debt, Total Other interest Allowance for borrowed funds used during construction Interest And Debt Expense Interest expense NET INTEREST EXPENSE Interest expense INCOME BEFORE INCOME TAX EXPENSE INCOME FROM CONTINUING OPERATIONS BEFORE TAXES INCOME BEFORE INCOME TAX EXPENSE INCOME BEFORE INCOME TAX EXPENSE INCOME TAX EXPENSE Income Tax Expense (Benefit), Total Net Income NET INCOME NET INCOME Cumulative preferred dividends Cumulative preferred dividends Preferred stock dividend requirements of subsidiary Dividends, Preferred Stock, Total NET INCOME FOR COMMON STOCK Net income for common stock NET INCOME FOR COMMON STOCK Net income for common stock Earnings per share - Basic Net income for common stock per common share - basic Net income for Common stock, Basic Earnings per Common Share - Basic Net income for common stock Earnings per share - Diluted Net income for common stock per common share - diluted Earnings Per Share, Diluted, Total Earnings per Common Share - Diluted Net income for common stock DIVIDENDS DECLARED PER SHARE OF COMMON STOCK Dividends declared per share of common stock AVERAGE NUMBER OF SHARES OUTSTANDING - BASIC (IN MILLIONS) Weighted average common shares outstanding - Basic Weighted Average Number of Shares Outstanding, Basic, Total Average number of shares outstanding - Basic (In Millions) AVERAGE NUMBER OF SHARES OUTSTANDING - DILUTED (IN MILLIONS) Adjusted weighted average common shares outstanding - Diluted Adjusted weighted average common shares outstanding - Diluted Average number of shares outstanding - Diluted (In Millions) Consolidated Statement Of Cash Flows OPERATING ACTIVITIES PRINCIPAL NON-CASH CHARGES/(CREDITS) TO INCOME Depreciation, Depletion and Amortization Depreciation, Depletion and Amortization, Total Depreciation and amortization Deferred Income Tax Expense (Benefit) Deferred Income Tax Expense (Benefit), Total Deferred income taxes Public Utilities, Allowance for Funds Used During Construction, Additions Common equity component of allowance for funds used during construction Common equity component of allowance for funds used during construction Net derivative (gains)/losses Net derivative (gains)/losses Net derivative (gains)/losses Other non-cash items (net) Other non-cash items (net) Other Noncash Income (Expense), Total CHANGES IN ASSETS AND LIABILITIES Accounts receivable-customers, less allowance for uncollectibles Accounts receivable - customers, less allowance for uncollectibles Materials and supplies, including fuel oil and gas in storage Materials and supplies, including fuel oil and gas in storage Increase (Decrease) in Inventories, Total Other receivables and other current assets Other receivables and other current assets Other - net Increase (Decrease) in Prepaid Expense Prepayments Prepayments Increase (Decrease) in Accounts Payable Accounts payable Increase (Decrease) in Accounts Payable, Total Accounts payable Increase (Decrease) in Pension and Postretirement Obligations Increase (Decrease) in Pension and Postretirement Obligations, Total Pensions and retiree benefits Increase (Decrease) in Property and Other Taxes Payable Accrued taxes Increase (Decrease) in Interest Payable, Net Accrued interest Deferred charges, deferred derivative losses, noncurrent assets and other regulatory assets Deferred charges, deferred derivative losses, noncurrent assets and other regulatory assets Deferred credits and other regulatory liabilities Increase (Decrease) in Deferred Liabilities, Total Increase Decrease In Other Operating Assets Other assets Other assets Increase (Decrease) in Other Operating Assets, Total Other liabilities Increase (Decrease) in Other Operating Liabilities, Total NET CASH FLOWS FROM OPERATING ACTIVITIES NET CASH FLOWS FROM OPERATING ACTIVITIES NET CASH FLOWS FROM OPERATING ACTIVITIES NET CASH FLOWS FROM OPERATING ACTIVITIES Net Cash Flows From Operating Activities INVESTING ACTIVITIES Utility construction expenditures Utility construction expenditures Cost of removal less salvage Cost of removal less salvage Payments for (Proceeds from) Removal Costs, Total Non-utility construction expenditures Non-utility construction expenditures Payments to Acquire Property, Plant, and Equipment, Total Payments for (Proceeds from) Other Investing Activities Proceeds from investment tax credits and grants related to renewable energy investments Loan to affiliate Loan to Pilesgrove solar project Common equity component of allowance for funds used during construction NET CASH FLOWS USED IN INVESTING ACTIVITIES Net Cash Flows (Used In)/From Investing Activities NET CASH FLOWS USED IN INVESTING ACTIVITIES NET CASH FLOWS (USED IN)/FROM INVESTING ACTIVITIES FINANCING ACTIVITIES Proceeds from repayment of short-term debt Net (payments of)/proceeds from short-term debt Proceeds from (Repayments of) Short-term Debt, Total Net proceeds from short-term debt Retirement of long-term debt Retirement of long-term debt Repayments of Long-term Debt, Total Proceeds from Issuance of Long-term Debt Issuance of long-term debt Proceeds from Issuance of Long-term Debt, Total Issuance of common stock Proceeds from common stock issued Common shares issued Payments for Repurchase of Common Stock Repurchase of common stock Payments of Debt Issuance Costs Debt issuance costs Debt issuance costs Capital contribution by parent Contributions to subsidiaries Common stock dividends Common stock dividends Preferred stock dividends Preferred stock dividends Net Cash Provided By Used In Financing Activities NET CASH FLOWS (USED IN)/FROM FINANCING ACTIVITIES CASH AND TEMPORARY CASH INVESTMENTS: NET CHANGE FOR THE PERIOD NET CHANGE FOR THE PERIOD Cash and temporary cash investments BALANCE AT END OF PERIOD BALANCE AT BEGINNING OF PERIOD Cash and Cash Equivalents, at Carrying Value, Total SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION Interest Interest Paid, Total Income taxes Income taxes Consolidated Balance Sheet Public Utility, Property, Plant and Equipment [Table] Public Utility [Axis] Utility Plant [Domain] Electricity Generation Plant, Non-Nuclear [Member] Steam Plant [Member] Independent Transmission and Distribution System [Member] Electric Transmission [Member] Gas Transmission [Member] ASSETS CURRENT ASSETS Accounts receivable - customers, less allowance for uncollectible accounts Accounts receivable - other Accounts Receivable, Net, Current, Total Accounts receivable - customers, less allowance for uncollectible accounts Unbilled revenues Accrued unbilled revenue Accrued unbilled revenue Other receivables, less allowance for uncollectible accounts Other receivables, less allowance for uncollectible accounts Accounts receivable from affiliated companies Loan receivable from Pilesgrove solar project Energy related inventory, fuel oil, gas and materials and supplies, cost Energy related inventory, fuel oil, gas and materials and supplies, cost Fuel oil, gas in storage, materials and supplies, at average cost Fuel oil, gas in storage, materials and supplies, at average cost Prepayments Prepaid Expense, Current, Total Regulatory assets - current Regulatory assets Other current assets Other current asset TOTAL CURRENT ASSETS TOTAL CURRENT ASSETS TOTAL CURRENT ASSETS Total Current Assets INVESTMENTS Long-term Investments, Total Investments in subsidiaries and others UTILITY PLANT, AT ORIGINAL COST UTILITY PLANT AT ORIGINAL COST Public Utilities, Property, Plant and Equipment, Transmission and Distribution Utility plant, at original cost Public Utilities, Property, Plant and Equipment, Transmission and Distribution, Total Public Utilities Property Plant And Equipment General General BALANCE AS OF MARCH 31, 2010 Public Utilities Property Plant And Equipment Gross TOTAL Less: Accumulated depreciation Annual depreciation allowance Net Net Utility Plant Public Utilities, Property, Plant and Equipment, Construction Work in Progress Construction work in progress Tangible assets that are held by an entity for use in the production or supply of utilities and that are expected to provide economic benefit for more than one year; net of accumulated depreciation. NET UTILITY PLANT NET UTILITY PLANT NON-UTILITY PLANT NON-UTILITY PROPERTY NON-UTILITY PLANT Tangible assets that are held by an entity for use other than utility production; net of accumulated depreciation. Non Utility Property Net Non-utility property, less accumulated depreciation Non-utility property, less accumulated depreciation of $53 and $51 in 2011 and 2010, respectively Construction in Progress, Gross Construction work in progress NET PLANT Property, Plant and Equipment, Net, Ending Balance Property, Plant and Equipment, Net, Beginning Balance NET PLANT OTHER NONCURRENT ASSETS Goodwill BS Goodwill, Ending Balance Goodwill, Beginning Balance Goodwill Goodwill, Total Intangible assets, less accumulated amortization of $3 and $2 in 2010 and 2009, respectively Intangible Assets, Net (Excluding Goodwill), Total Intangible assets, less accumulated amortization of $3 in 2011 and 2010 Regulatory Assets Noncurrent Regulatory assets Regulatory assets - long-term Other deferred charges and noncurrent assets Other Assets, Noncurrent, Total Total Other Assets Total Other Assets TOTAL OTHER NONCURRENT ASSETS TOTAL OTHER NONCURRENT ASSETS Other Assets TOTAL ASSETS Total Assets TOTAL ASSETS TOTAL ASSETS LIABILITIES AND SHAREHOLDER'S EQUITY CURRENT LIABILITIES Long-term debt due within one year Less: long-term debt due within one year Long-term Debt, Current Maturities, Total Accounts Payable, Current Accounts Payable, Current, Total Accounts payable Accounts payable to affiliated companies Customer deposits Taxes Payable, Current Taxes Payable, Current, Total Accrued taxes Current portion of intercompany tax payable Current Portion Of Intercompany Tax Payable Accrued taxes to affiliated companies Interest Payable, Current Accrued interest Accrued wages Employee-related Liabilities, Current, Total Derivative Liabilities, Current Fair value of derivative liabilities Other current liabilities Other Liabilities, Current, Total TOTAL CURRENT LIABILITIES Total Current Liabilities TOTAL CURRENT LIABILITIES TOTAL CURRENT LIABILITIES NONCURRENT LIABILITIES Obligations under capital leases Provision for injuries and damages. Provision for injuries and damages Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent, Total Pensions and retiree benefits Superfund and other environmental costs Asset Retirement Obligations, Noncurrent Asset Retirement Obligations, Noncurrent, Ending Balance Asset retirement obligations Asset Retirement Obligations, Noncurrent, Total BALANCE AS OF MARCH 31, 2010 Derivative Liabilities, Noncurrent Fair value of derivative liabilities Other noncurrent liabilities Other Liabilities, Noncurrent, Total TOTAL NONCURRENT LIABILITIES NONCURRENT LIABILITIES TOTAL NONCURRENT LIABILITIES Noncurrent Liabilities Deferred Credits and Regulatory Liabilities [Abstract] Deferred Credits And Regulatory Liabilities Abstract DEFERRED CREDITS AND REGULATORY LIABILITIES Represents the noncurrent portion of deferred tax liabilities and the reserve for accumulated deferred investment tax credits as of the balance sheet date, which result from applying the applicable tax rate to net taxable temporary differences pertaining to each jurisdiction to which the entity is obligated to pay income tax. A noncurrent taxable temporary difference is a difference between the tax basis and the carrying amount of a noncurrent asset or liability in the financial statements prepared in accordance with generally accepted accounting principles. In a classified statement of financial position, an enterprise shall separate deferred tax liabilities and assets into a current amount and a noncurrent amount. Deferred tax liabilities and assets shall be classified as current or noncurrent based on the classification of the related asset or liability for financial reporting. A deferred tax liability or asset that is not related to an asset or liability for financial reporting, including deferred tax assets related to carryforwards, shall be classified according to the expected reversal date of the temporary difference. This is the remaining investment credit, which will reduce the cost of services collected from ratepayers by a ratable portion over the investment's regulatory life. Deferred Tax Liabilities Noncurrent And Accumulated Deferred Investment Tax Credit Deferred income taxes and investment tax credits Regulatory liabilities Non current BALANCE AS OF JUNE 30, 2010 Regulatory liabilities Regulatory Liability, Noncurrent, Total BALANCE AS OF JUNE 30, 2010 Other deferred credits Deferred Credits and Regulatory Liabilities Deferred Credits And Regulatory Liabilities TOTAL DEFERRED CREDITS AND REGULATORY LIABILITIES TOTAL DEFERRED CREDITS AND REGULATORY LIABILITIES Long-term Debt, Excluding Current Maturities LONG-TERM DEBT Long-term Debt, Excluding Current Maturities, Total LONG-TERM DEBT (See Statement of Capitalization) SHAREHOLDER'S EQUITY Total value of common stock equity Common Stock Equity ENDING BALANCE BEGINNING BALANCE Common shareholders' equity (See Statement of Shareholders' Equity) TOTAL COMMON SHAREHOLDERS' EQUITY Preferred stock Preferred Stock, Value, Issued, Ending Balance Preferred Stock, Value, Issued, Beginning Balance Preferred stock of subsidiary TOTAL PREFERRED STOCK Cumulative Preferred Stock TOTAL SHAREHOLDER'S EQUITY Stockholders' Equity Attributable to Parent, Ending Balance Stockholders' Equity Attributable to Parent, Beginning Balance TOTAL SHAREHOLDER'S EQUITY TOTAL LIABILITIES AND SHAREHOLDER'S EQUITY Total Liabilities And Shareholders' Equity TOTAL LIABILITIES AND SHAREHOLDER'S EQUITY TOTAL LIABILITIES AND SHAREHOLDER'S EQUITY Accounts receivable-customers, allowance for uncollectible accounts Allowance for Doubtful Accounts Receivable, Current, Ending Balance Allowance for Doubtful Accounts Receivable, Current, Beginning Balance A provision for other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible. Allowance For Doubtful Other Receivable Current Other receivables, allowance for uncollectible accounts Non-utility property, accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Ending Balance Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Beginning Balance Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Total Intangible assets, accumulated amortization Consolidated Statement Of Comprehensive Income OTHER COMPREHENSIVE INCOME/(LOSS), NET OF TAXES OTHER COMPREHENSIVE INCOME/(LOSS), NET OF TAXES Pension plan liability adjustments, net of taxes of $1 and $3 in 2010 and $1 and $2 in 2009, respectively Pension plan liability adjustments, net of taxes of $1 and $3 in 2011 and $1 and $3 in 2010, respectively Other Comprehensive Income, Defined Benefit Plans Adjustment, Net of Tax, Total Pension plan liability adjustments, net of taxes of $0 in 2011 and $2 in 2010 Other comprehensive income TOTAL OTHER COMPREHENSIVE INCOME/(LOSS), NET OF TAXES COMPREHENSIVE INCOME COMPREHENSIVE INCOME Comprehensive Income Available to Common Stockholders, Net of Tax Comprehensive Income Available To Common Stockholders Net Of Tax COMPREHENSIVE INCOME FOR COMMON STOCK Pension plan liability adjustments, taxes Other Comprehensive Income, Defined Benefit Plans, Tax, Total Pension plan liability adjustments, net of taxes of $1 and $3 in 2011 and $1 and $3 in 2010, respectively Consolidated Statment Of Common Stockholders' Equity Statement, Equity Components [Axis] Equity Component [Domain] Common Stock [Member] Additional Paid- In Capital [Member] Retained Earnings [Member] Treasury Stock [Member] Repurchased Con Edison Stock Repurchased Con Edison Stock [Member] Other Changes Stockholders Equity Ending Balance Capital Stock Expense [Member] Accumulated Other Comprehensive Income/(Loss) [Member] Common Stock Equity Shares Common Stock Equity Shares ENDING BALANCE (in shares) BEGINNING BALANCE (in shares) TOTAL COMMON SHAREHOLDERS' EQUITY BEFORE, (In shares) Capital contributions from parent. Capital Contributions From Parent Capital contribution from parent Common stock dividend to parent Common stock dividends Common stock dividend Dividends, Common Stock, Total Stock Issued During Period, Shares, Dividend reinvestment and Employee Stock Purchase Plan Stock Issued During Period Shares Dividend Reinvestment And Employee Stock Purchase Plan Issuance of common shares-dividend reinvestment and employee stock plans (in shares) Value of stock issued as a result of dividend reinvestment and employee stock purchase plan recorded above par value. Stock Issued During Period Value Dividend Reinvestment And Employee Stock Purchase Plan Issuance of common shares-dividend reinvestment and employee stock plans Treasury Stock, Value Treasury Stock, Value, Ending Balance Treasury Stock, Value, Beginning Balance Common stock repurchases Treasury Stock, Shares, Retired Common stock repurchases, shares Other Comprehensive Income (Loss), before Tax Other comprehensive income Other Comprehensive Income (Loss), before Tax, Total General Information [Abstract] General Description of Activities of Parent Company Description of Activities of Parent Company [Text Block] General Summary Of Significant Accounting Policies Significant Accounting Policies Summary Of Significant Accounting Policies Regulatory Matters Public Utilities disclosure of Regulatory Matters Pending Public Utilities disclosure of Regulatory Matters Pending [Text Block] Regulatory Matters Short-Term Borrowing Short Term Debt Short-Term Borrowing Pension Benefits Pension and Other Postretirement Benefits Disclosure [Text Block] Pension Benefits Other Postretirement Benefits [Abstract] Other Postretirement Benefits Postemployment Benefits Disclosure [Text Block] Other Postretirement Benefits Environmental Matters [Abstract] Environmental Matters Environmental Loss Contingency Disclosure Environmental Matters Other Material Contingencies [Abstract] Other Material Contingencies Commitments and Contingencies Disclosure [Text Block] Other Material Contingencies Financial Information By Business Segment Segment Reporting Disclosure Financial Information By Business Segment Derivative Instruments And Hedging Activities Derivative Instruments and Hedging Activities Disclosure Number of Derivative Contracts by Commodity Type Derivative Instruments And Hedging Activities Fair Value Measurements Fair Value Measurement Inputs Disclosure Fair Value Measurements New Financial Accounting Standards [Abstract] New Financial Accounting Standards New Financial Accounting Standards [Text Block] New Financial Accounting Standards [Text Block] New Financial Accounting Standards Earnings Per Share, Policy [Text Block] Earnings Per Common Share Earnings Per Common Share Schedule Of Regulatory Assets And Liabilities Table [Text Block] Schedule Of Regulatory Assets And Liabilities Table [Text Block] Regulatory Assets and Liabilities Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures Net Periodic Pension Benefit Costs Net Periodic Postretirement Benefit Costs Defined Benefit Plans Disclosures, Defined Benefit Plans [Axis] Defined Benefit Plans [Domain] Other Postretirement Benefits [Member] Accrued Liabilities And Regulatory Assets Text Block Accrued Liabilities And Regulatory Assets Text Block Accrued Liabilities And Regulatory Assets Environmental Remediation Costs Incurred Related to Super fund Sites [Text Block] Environmental Remediation Costs Incurred Related to Super fund Sites [Text Block] Environmental Remediation Costs Accrued Liabilities For Asbestos Suits And Workers Compensation Proceedings [Text Block] Accrued Liabilities For Asbestos Suits And Workers Compensation Proceedings [Text Block] Accrued Liabilities For Asbestos Suits And Workers' Compensation Proceedings Schedule of Guarantor Obligations [Text Block] Total Guarantees Schedule of Segment Reporting Information, by Segment [Text Block] Financial Data For The Business Segments Schedule of Energy Price Hedges, Fair Value Schedule of Energy Price Hedges, Fair Value text block Energy Price Hedging Fair Values Fair Value of Commodity Derivatives Fair Values Of The Companies' Commodity Derivatives Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance [Text Block] Changes In The Fair Values Of Commodity Derivatives Schedule of Derivative Instruments [Text Block] Number Of Derivative Contracts By Commodity Type Disclosure of Credit Derivatives [Text Block] Aggregate Fair Value Of All Derivative Instruments With Credit Risk Related Contingent Features Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Assets And Liabilities Measured At Fair Value On A Recurring Basis Fair Value Assets Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Text Block Fair Value Assets Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Text Block Reconciliation Of The Beginning And Ending Net Balances For Assets And Liabilities Measured At Level 3 Fair Value Incremental Common Shares Attributable to Contingently Issuable Shares Add: Incremental shares attributable to effect of potentially dilutive securities Schedule of Regulatory Assets [Table] Regulatory Asset [Axis] Regulatory Asset [Domain] Regulatory Asset for difference between Liability to Fair Value of Plan Assets and Projected Benefit Obligation. Unrecognized Pension and Other Postretirement Costs [Member] Future Federal Income Tax [Member] Environmental Remediation Costs [Member] Regulatory Asset for reconciliation of actual pension and other postretirement benefit expenses to the level allowed in rates. Pension and Other Post Retirement Benefits Deferrals [Member] Regulatory Asset for timing differences between taxes collected and paid by the Utilities to fund mass transportation. Revenue Taxes [Member] Net Electric Deferrals [Member] Net Electric Deferrals [Member] Regulatory Asset to collect New York Surcharge for Temporary State Energy and Utility Service Conservation Assessment - 04/09 - 03/14 Surcharge for New York State Assessment [Member] Deferred Storm Costs [Member] Deferred Storm Costs [Member] O and R Transition Bond Charges [Member] O & R Transition Bond Charges [Member] Regulatory Asset for deferral of change in fair value of derivative instrument. Deferred Derivative Losses - Long-Term [Member] Regulatory Asset for reconciliation of actual property tax expense to the level allowed in rates. Property Tax Reconciliation [Member] Workers Compensation [Member] Workers' Compensation [Member] Regulatory Asset for non-capital costs (net of federal reimbursement and insurance recoveries) incurred by CECONY for emergency response to the 09/11/01 attack on the WTC, and for restoration of electric, gas, and steam transmission and distribution facilities damaged in the attack. World Trade Center Restoration Costs [Member] Recoverable Energy [Member] Recoverable Energy [Member] Other [Member] Regulatory Asset for deferral of change in fair value of derivative instrument. Deferred Derivative Losses - Current [Member] Recoverable Energy Costs - Current [Member] Allowance for Cost of Removal Less Salvage [Member] Revenue Decoupling Mechanism [Member] Revenue Decoupling Mechanism [Member] World Trade Center Settlement Proceeds [Member] World Trade Center Settlement Proceeds [Member] Carrying Changes On T&D Net Plant [Member] Carrying Changes On T&D Net Plant [Member] Energy Efficiency Programs [Member] Energy Efficiency Programs [Member] New York State Tax Refund [Member] New York State Tax Refund [Member] Gain On Sale Of Properties [Member] Gain on Sale of Properties [Member] Bonus Depreciation [Member] Bonus Depreciation [Member] Expenditure Prudence Proceeding [Member] Expenditure Prudence Proceeding [Member] Other Liabilities [Member] Net Unbilled Revenue Deferrals - Current [Member] Net Unbilled Revenue Deferrals - Current [Member] Refundable Energy Cost - Current [Member] Refundable Energy Cost - Current [Member] Regulatory Liability for reserve of change in fair value of derivative instrument. Deferred Derivative Gains - Current [Member] Regulatory Assets Regulatory assets Regulatory Assets, Total Total Regulatory Assets Regulatory liability - current Regulatory liabilities - current Regulatory Liability, Current, Total Regulatory Liabilities Total regulatory liabilities Regulatory Liabilities, Total Total Regulatory Liabilities Commercial Paper, at Carrying Value Commercial paper, at carrying value Commercial paper outstanding Line of Credit Facility, Amount Outstanding Letters of credit outstanding under the credit agreement Pension Benefits [Member] Pension Benefits [Member] Non-Qualified Supplemental Pension Plans [Member] Non-Qualified Supplemental Pension Plans [Member] Defined Benefit Plan, Service Cost Service cost - including administrative expenses Service cost Defined Benefit Plan, Interest Cost Interest cost on accumulated other postretirement benefit obligation Interest cost on projected benefit obligation Interest cost on accumulated other postretirement benefit obligation Defined Benefit Plan, Expected Return on Plan Assets Expected return on plan assets Expected return on plan assets Defined Benefit Plan, Amortization of Gains (Losses) Amortization of net actuarial loss Amortization of net actuarial loss Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Amortization of prior service cost Amortization of prior service cost Defined Benefit Plan, Net Periodic Benefit Cost NET PERIODIC POSTRETIREMENT BENEFIT COST NET PERIODIC BENEFIT COST NET PERIODIC BENEFIT COST Amortization of Regulatory Asset Amortization of regulatory asset Total Periodic Benefit Cost After Amortization of Regulatory Asset Total Periodic Benefit Cost After Amortization of Regulatory Asset TOTAL PERIODIC BENEFIT COST TOTAL PERIODIC BENEFIT COST Defined Benefit Plan Cost Capitalized Defined Benefit Plan Cost Capitalized Cost capitalized Defined Benefit Plan Cost Deferred Defined Benefit Plan Cost Deferred Cost deferred Cost deferred Defined Benefit Plan Cost Charged To Operating Expenses Defined Benefit Plan Cost Charged To Operating Expenses Cost charged to operating expenses Cost charged to operating expenses Cost charged (credited) to operating expenses Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year Estimated future employer contributions Defined Benefit Plan, Funded Status of Plan Non-qualified supplement pension plan, funded Defined Benefit Plan, Funded Status of Plan, Total Defined Benefit Plan, Amortization of Transition Obligations (Assets) Amortization of transition obligation Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year Expected contributions Site Contingency [Table] Site Contingency by Nature [Axis] Site Contingency, Nature of Contingency [Domain] Manufactured Gas Plant Sites Manufactured Gas Plant Sites [Member] Other Superfund Sites Other Superfund Sites [Member] Superfund Sites [Member] Superfund Sites [Member] Accrual for Environmental Loss Contingencies Accrual for Environmental Loss Contingencies, Ending Balance Accrual for Environmental Loss Contingencies, Beginning Balance Accrued liability Accrual for Environmental Loss Contingencies, Total Accrual for environmental loss contingencies Environmental Remediation Expense Remediation costs incurred Asbestos Suits [Member] Asbestos Suits [Member] Schedule of Guarantor Obligations [Table] Guarantor Obligations by Nature [Axis] Guarantor Obligations, Nature [Domain] Tax deficiency paid in December 2005 Tax Deficiency Paid in December 2005 [Member] Interest in April 2006 [member] Interest in April 2006 [Member] Interest Up To March Two Thousand Eleven [Member] Interest up to March 2011 [Member] Disallowance of Tax 1998-2007 [Member] Disallowance of Tax 1998-2007 [Member] Disallowance of Tax 2009 [Member] Disallowance of Tax 2009 [Member] Disallowance of Tax 2008 [Member] Disallowance of Tax 2008 [Member] Lease in lease out total investment Lease in lease out total investment Lease in lease out total financed by equity Lease in lease out total financed by equity Lease In Lease Out Total Financed By Non Recourse Long Term Debt Lease In Lease Out Total Financed By Non Recourse Long Term Debt Lease in lease out total financed by long-term debt The company's investment in leverage leases Leveraged Leases, Net Investment in Leveraged Leases Disclosure, Investment in Leveraged Leases, Net, Total Leveraged Lease Gross Investment In Leveraged Leases Disclosure Investment In Leveraged Leases Gross Leveraged Lease Gross Investment In Leveraged Leases Disclosure Investment In Leveraged Leases Gross Gross investment in leverage leases Deferred Tax Liabilities, Leasing Arrangements Deferred tax liabilities Income Tax Paid Upon IRS Examination Income Tax Paid Upon IRS Examination Tax deficiency paid to IRS Income Tax Examination, Interest from Examination Interest paid related to tax deficiency Interest paid related to tax deficiency IRS Disallowed Deduction IRS Disallowed Deduction Disallowed deduction Tax Savings From Lease In Lease Out Transactions Tax Savings From Lease In Lease Out Transactions Tax savings from lease in lease out transactions Guarantee Obligations Maximum Exposure Guarantee obligations maximum exposure Statement, Scenario [Axis] Scenario, Unspecified [Domain] Guarantee Duration One To Three Years [Member] Guarantee Duration, 0-3 Years [Member] Guarantee Duration Four To Ten Years [Member] Guarantee Duration, 4-10 Years [Member] Guarantee duration, greater than 10 years Guarantee Duration, Greater than 10 Years [Member] Financial And Performance Guarantee For Commodity Transactions [Member] Financial and Performance Guarantee for Commodity Transactions [Member] Financial And Performance Guarantee For Intra Company [Member] Financial and Performance Guarantee for Intra-Company [Member] Financial And Performance Guarantee Other [Member] Financial and Performance Guarantee Other [Member] Schedule of Segment Reporting Information, by Segment [Table] Segment Reporting Information, by Segment [Axis] Reporting Segment [Domain] CECONY - Electric [Member] CECONY - Electric [Member] CECONY - Gas [Member] CECONY - Gas [Member] CECONY - Steam [Member] CECONY - Steam [Member] O&R - Electric [Member] O&R - Electric [Member] O&R - Gas [Member] O&R - Gas [Member] Competitive Energy Businesses [Member] Competitive Energy Businesses [Member] Con Edison - Competitive energy businesses [Member] Other Revenues and Eliminations in Segment Information [Member] Other Revenues and Eliminations in Segment Information [Member] Consolidation Adjustments [Member] O R [Member] O&R [Member] Segment Reporting, Segment Revenue Operating revenues Segment Reporting Information, Revenue for Reportable Segment, Total Segment Reporting Information, Intersegment Revenue Inter-segment revenues Investment Holdings [Table] Maximum Potential Future Exposure On Credit Risk Derivatives Total Maximum Potential Future Exposure On Credit Risk Derivatives Total Energy supply and hedging activities credit exposure total Maximum Potential Future Exposure On Credit Risk Derivatives With Investment Grade Counterparties Maximum Potential Future Exposure On Credit Risk Derivatives With Investment Grade Counterparties Makeup of net credit exposure counterparties Maximum Potential Future Exposure On Credit Risk Derivatives With Commodity Exchange Brokers Maximum Potential Future Exposure On Credit Risk Derivatives With Commodity Exchange Brokers Makeup of net credit exposure primarily with commodity exchange Credit Exposure Independent System Operators Credit Exposure Independent System Operators Independent system operators DescriptionOfDerivativeActivityVolume Number of contracts considered derivatives Derivative, Fair Value, Net Fair value of net derivative assets/(liabilities) - gross Fair value of net derivative assets/(liabilities) - gross Derivative, Fair Value, Net, Total Derivative Asset, Fair Value, Amount Offset Against Collateral Impact of netting of cash collateral Impact of netting of cash collateral Derivative, Fair Value, Amount Offset Against Collateral, Net Fair value of net derivative assets/(liabilities) - net Fair value of net derivative assets/(liabilities) - net Fair value of net derivative assets/(liabilities) - net Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Derivatives, Fair Value, by Derivative Instrument Risk [Axis] Derivative Contract Type [Domain] Asset Derivatives [Member] Derivative Asset [Member] Liability Derivative [Member] Derivative Liability [Member] Derivatives, Fair Value, by Balance Sheet Location [Axis] Balance Sheet Location [Domain] Other Current Assets [Member] Other Current Assets [Member] Other Deferred Charges and Non-current Assets [Member] Other Deferred Charges and Non-Current Assets [Member] Fair Value of Derivative Liabilities, Current [Member] Fair Value of Derivative Liabilities, Current [Member] Fair Value of Derivative Liabilities, Long Term [Member] Fair Value of Derivative Liabilities, Long Term [Member] Derivative Asset Not Designated as Hedging Instrument, Fair Value Fair value of derivative assets Derivative Asset, Fair Value, Net, Total Derivative Liability, Fair Value, Amount Offset Against Collateral Impact of netting Impact of netting Derivative Liability, Fair Value, Amount Offset Against Collateral, Total Derivative Asset Not Designated As Hedging Instrument Fair Value Net After Offset Under Master Netting Agreement Derivative Asset Not Designated As Hedging Instrument Fair Value Net After Offset Under Master Netting Agreement Net derivatives asset Derivative Liability Not Designated as Hedging Instrument, Fair Value Fair value of derivative liabilities Derivative Liability, Fair Value, Net, Total Derivative Liability Not Designated As Hedging Instrument Fair Value Net After Offset Under Master Netting Agreement Derivative Liability Not Designated As Hedging Instrument Fair Value Net After Offset Under Master Netting Agreement Net derivatives liability Deferred Derivative Gains [Member] Deferred Derivative Gains [Member] Regulatory Liabilities, Long Term [Member] Regulatory Liabilities, Long Term [Member] Deferred Derivative Losses [Member] Deferred Derivative Losses [Member] Recoverable Energy Costs [Member] Recoverable Energy Costs [Member] Regulatory Assets, Long Term [Member] Regulatory Assets, Long Term [Member] Derivative Instruments, Gain (Loss) by Income Statement Location [Axis] Income Statement and Other Comprehensive Income Location [Domain] Purchased Power Expense [Member] Purchased Power Expense [Member] Gas Purchased for Resale [Member] Gas Purchased for Resale [Member] Non-utility Revenue [Member] Non-utility Revenue [Member] Deferred derivative gains Deferred derivative gains Current-Deferred derivative gains Deferred Derivative Gains Total Deferred Derivative Gains Total Total deferred gains Unrealized Gain (Loss) on Derivatives and Commodity Contracts Deferred derivative losses, current Unrealized Gain (Loss) on Derivatives and Commodity Contracts, Total Deferred gain/(loss), asset Deferred gain/(loss), asset Deferred gain/(loss), liability Deferred gain/(loss), liability Total deferred losses Net deferred gain/(loss) Net deferred gain/(loss) Net deferred losses Derivative Instruments, Gain (Loss) Recognized in Income, Net Pre-tax gain/(loss) recognized in income Derivative Instruments, Gain (Loss) Recognized in Income, Net, Total Unrealized gain (loss) on derivatives Unrealized gain/(loss) on derivatives, tax Description Of Derivative Activity Volume Electric Derivatives [Member] Description of Derivative Activity Volume Electric Derivatives [Member] Description Of Derivative Activity Volume Gas Derivatives [Member] Description of Derivative Activity Volume Gas Derivatives [Member] Number of Energy Contracts Number of Energy Contracts MWHS MWHS MWhs Number of Capacity Contracts Number of Capacity Contracts MWs MWs Dths Dths Additional Collateral Required Due To Loss of Unsecured Credit [Member] Additional Collateral Required Due to Loss of Unsecured Credit [Member] Additional Collateral Aggregate Fair Value Down One Level [Member] Additional Collateral Aggregate Fair Value Down One Level [Member] Additional Collateral Aggregate Fair Value Down Below Investment Grade [Member] Additional Collateral Aggregate Fair Value Down Below Investment Grade [Member] Credit Risk Derivatives, at Fair Value, Net Aggregate fair value - net liabilities Credit Risk Derivatives, at Fair Value, Net, Total Collateral Already Posted, Aggregate Fair Value Collateral posted Additional Collateral, Aggregate Fair Value Additional collateral Fair Value, Assets Measured on Recurring Basis, Gain (Loss) Included in Other Income Gain (loss) on Level 3 energy derivative assets Gain (loss) on Level 3 energy derivative assets Fair Value, Liabilities Measured on Recurring Basis, Gain (Loss) Included in Other Income Gains (loss) on Level 3 energy derivative liabilities Fair Value, Assets Measured on Recurring Basis, Gain (Loss) Included in Purchased Power Costs Fair Value, Assets Measured on Recurring Basis, Gain (Loss) Included in Purchased Power Costs Loss on Level 3 energy derivative assets for purchased power costs Loss on Level 3 energy derivative assets for purchased power costs Fair Value, Liabilities Measured on Recurring Basis, Gain (Loss) Included in purchased power costs Fair value, liabilities measured on recurring basis, gain (loss) included in purchased power costs Gain on Level 3 energy derivative liabilities for purchased power costs Gain on Level 3 energy derivative liabilities for purchased power costs Fair value, assets measured on recurring basis, change in unrealized gain (loss) included in other income Gain (Loss) on change in fair value relating to Level 3 energy derivative assets Gain (Loss) on change in fair value relating to Level 3 energy derivative assets Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Purchased Power Costs Fair value, assets measured on recurring basis, change in unrealized gain (loss) included in purchased power costs Gain on change in fair value relating to Level 3 energy derivative assets for purchased power costs Gain on change in fair value relating to Level 3 energy derivative assets for purchased power costs Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Fair Value, Estimate Not Practicable, Disclosure Items [Axis] Fair Value, Estimate Not Practicable, Disclosure Items [Domain] Fair Value Commodity [Member] Commodity [Member] Commodity Fair Value Interest Rate Contract [Member] Fair Value Interest Rate Contract [Member] Interest Rate Contract Fair Value Other [Member] Fair Value Other Assets [Member] Fair Value, Assets Measured on Recurring Basis, Disclosure Items [Axis] Fair Value, Assets Measured on Recurring Basis, Disclosure Items [Domain] Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 3 [Member] Netting Adjustments [Member] Derivative Assets Derivative assets Derivative Assets, Total Commodity assets Derivative Assets Commodity Total Derivative Assets Commodity Total Total assets Derivative Assets Commodity Total Fair Value Measurement With Unobservable Inputs Reconciliation Liability Transfers Into Level 3 Transfer in Fair Value Measurement With Unobservable Inputs Reconciliation Liability Transfers Out Of Level 3 Transfer out Derivative Liabilities Derivative liabilities Derivative Liabilities, Total Commodity liabilities Derivative Liabilities Commodity Total Derivative Liabilities Commodity Total Commodity Total liabilities Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Ending Balance Beginning Balance Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings Included in Earnings Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Included In regulatory Assets And Liabilities Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Included In regulatory Assets And Liabilities Included in Regulatory Assets and Liabilities Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Purchases Purchases Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Sales Sales Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Settlements Settlements Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net Transfers In/Out of Level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net, Total Companies [Member] Companies [Member] Investment Contract Counterparty [Axis] Contract Counterparty [Domain] Contract Counterparty [Domain] Non-Investment Grade Counterparties [Member] Non-Investment Grade Counterparties [Member] Other Current Liabilities [Member] Other Current Liabilities [Member]