Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Common Stock [Member] Common Stock [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum [Member] Minimum [Member] Maximum [Member] Maximum [Member] Defined Benefit Plan, Asset Categories [Axis] Defined Benefit Plan, Asset Categories [Axis] Plan Asset Categories [Domain] Plan Asset Categories [Domain] Industry Sector [Axis] Industry Sector [Axis] Industry Sector [Domain] Industry Sector [Domain] Health Care [Member] Health Care [Member] Health Care [Member] Prescription Drug [Member] Prescription Drug [Member] Prescription Drug [Member] Schedule of Defined benefit plans disclosures [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Schedule of Defined benefit plans [Domain] Defined Benefit Plan and Other Postretirement Benefit Plan [Domain] Postretirement Benefits [Member] Other Postretirement Benefit Plan [Member] Pension Plan [Member] Pension Plan [Member] Other Pension Plan [Member] Other Pension Plan [Member] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Pension and Postretirement Benefits [Abstract] Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract] New percentage of eligible earnings used to determine retirement benefits (in hundredths) Defined Benefit Plan Retirement Benefit Eligible Earnings Increased Percentage The increased percentage of earnings, effective January 1, 2009, used in the cash balance formula to determine a participant's retirement benefit. Percent vested Defined Benefit Plan Percentage Vested Represents the percentage vested after three years. Pension plan minimum vesting period (in years) Defined Benefit Pension Plan Vesting Period Description of the period of time after which plan participants become fully vested and are entitled to receive benefits under the non-contributory qualified defined benefit pension plan. Approximate amortization period of transition obligation (in years) Defined Benefit Plan Transition Obligation Amortization Period The period of time over which the transition obligation, resulting from future healthcare cost accruals, will be amortized. Components of net periodic costs [Abstract] Defined Benefit Plan, Net Periodic Benefit Cost [Abstract] Service cost Defined Benefit Plan, Service Cost Interest cost Defined Benefit Plan, Interest Cost Expected return on plan assets Defined Benefit Plan, Expected Return on Plan Assets Amortization of prior service cost (credit) Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Amortization of net loss Defined Benefit Plan, Amortization of Gains (Losses) Amortization of transition obligation Defined Benefit Plan, Amortization of Transition Obligations (Assets) Curtailment (1) Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments Settlement (2) Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements Net periodic cost Defined Benefit Plan, Net Periodic Benefit Cost Assumptions used to determine net periodic benefit (income) cost Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract] Discount rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Expected return on plan assets Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets Rate of increase in compensation levels Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase Change in benefit obligation [Roll Forward] Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] Benefit obligation, beginning of year Defined Benefit Plan, Benefit Obligation Participant contributions Defined Benefit Plan, Contributions by Plan Participants Benefits paid Defined Benefit Plan, Benefits Paid Actuarial (gain) loss Defined Benefit Plan, Actuarial Gain (Loss) Medicare reimbursement Defined Benefit Plan, Gross Prescription Drug Subsidy Receipts Received Plan amendment Defined Benefit Plan, Plan Amendments Settlement Defined Benefit Plan, Settlements, Plan Assets Curtailment Defined Benefit Plan, Curtailments Benefit obligation, end of year Change in plan assets [Rollforward] Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward] Fair value of plan assets, beginning of year Defined Benefit Plan, Fair Value of Plan Assets Employer contributions Defined Benefit Plan, Contributions by Employer Actual investment return (loss) Defined Benefit Plan, Actual Return on Plan Assets Fair value of plan assets, end of year Funded status of plan Defined Benefit Plan, Funded Status of Plan [Abstract] Funded status, end of year Defined Benefit Plan, Funded Status of Plan Amounts recognized in balance sheets Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract] Current liabilities-other Pension and Other Postretirement Defined Benefit Plans, Current Liabilities Other liabilities-benefit obligations Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent Net liability, end of year Pension and Other Postretirement Defined Benefit Plans, Liabilities Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year Defined Benefit Plan Prescription Drug Cost Trend Rate Assumed For Next Fiscal Year Defined Benefit Plan Prescription Drug Cost Trend Rate Assumed For Next Fiscal Year The assumed prescription drug cost trend rate for the next year used to measure the expected cost of benefits covered by the plan (gross eligible charges). This is based upon the annual rate of change in the cost of prescription drugs currently provided by the postretirement benefit plan, due to factors other than changes in the composition of the plan population by age and dependency status. Defined Benefit Plan, Ultimate Health Care Cost Trend Rate Defined Benefit Plan, Ultimate Health Care Cost Trend Rate Defined Benefit Plan, Year that Rate Reaches Ultimate Trend Rate Defined Benefit Plan, Year that Rate Reaches Ultimate Trend Rate Accumulated benefit obligation for all defined benefit pension plans Defined Benefit Plan, Accumulated Benefit Obligation Annualized individual discount rates based on time period, minimum Annualized individual discount rates based on time period, minimum Annualized individual discount rates based on time period, minimum Annualized individual discount rates based on time period, maximum Annualized individual discount rates based on time period, maximum Annualized individual discount rates based on time period, maximum Amounts reclassified from accumulated other comprehensive income: [Abstract] Amounts reclassified from accumulated other comprehensive income: [Abstract] Amounts reclassified from accumulated other comprehensive income: [Abstract] Beginning Balance Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax Other comprehensive income (loss) before reclassifications (1) Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Reclassification Adjustments and Tax Amounts reclassified from accumulated other comprehensive income: Amount reclassified from accumulated other comprehensive income [Abstract] Amount reclassified from accumulated other comprehensive income [Abstract] Amortization of prior service credit Other Comprehensive (Income) Loss, Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service Cost (Credit), before Tax Actuarial losses (2) Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), Net of Tax Total reclassifications from accumulated other comprehensive income Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, before Tax Tax expense Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax, Portion Attributable to Parent Net current period other comprehensive income Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax, Portion Attributable to Parent Ending Balance Total expense recognized in net periodic cost and other comprehensive income Amount Recognized in Net Periodic Benefit Cost and Other Comprehensive Income (Loss), before Tax Amounts recognized in accumulated other comprehensive loss Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax [Abstract] Unrecognized actuarial loss (gain) Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax Unrecognized prior service cost (credit) Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax Net amount recognized in accumulated other comprehensive loss Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax Changes in plan assets and benefit obligations recognized in other comprehensive income Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract] Net gain Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, before Tax Amortization of net loss Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), before Tax Total recognized in comprehensive income Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Tax, Portion Attributable to Parent Amounts that will be amortized from accumulated other comprehensive loss in next fiscal year Defined Benefit Plan, Amount to be Amortized from Accumulated Other Comprehensive Income (Loss) Next Fiscal Year [Abstract] Unrecognized actuarial loss Defined Benefit Plan, Future Amortization of Gain (Loss) Unrecognized prior service cost Defined Benefit Plan, Future Amortization of Prior Service Cost (Credit) Amounts in accumulated comprehensive loss to be recognized in net periodic cost in 2016 Defined Benefit Plan, Amount to be Amortized from Accumulated Other Comprehensive Income (Loss) Next Fiscal Year Pension benefits that have accumulated benefit obligations in excess of plan assets Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets [Abstract] Accumulated benefit obligation Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Accumulated Benefit Obligation Projected benefit obligation Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Projected Benefit Obligation Fair value of plan assets Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Fair Value of Plan Assets Effect of a one-percentage point change in assumed health care cost trend rates Defined Benefit Plan, Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates [Abstract] Effect of a one-percentage point increase on post-retirement benefit obligation Defined Benefit Plan, Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation Effect of a one-percentage point decrease on post-retirement benefit obligation Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation Effect of a one-percentage point increase on total service and interest cost Defined Benefit Plan, Effect of One Percentage Point Increase on Service and Interest Cost Components Effect of a one-percentage point decrease on total service and interest cost Defined Benefit Plan, Effect of One Percentage Point Decrease on Service and Interest Cost Components Condensed Financial Information of Parent Company Only Disclosure [Abstract] Condensed Income Statement [Table] Condensed Income Statement [Table] Legal entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Parent Company [Member] Parent Company [Member] Condensed Income Statements, Captions [Line Items] Condensed Income Statements, Captions [Line Items] Statements of Consolidated Income Income Statement [Abstract] Expenses: Operating Expenses [Abstract] Operation and Maintenance Expenses Operation and maintenance The amount of operating expense for the period for recurring costs associated with normal operations including general and administrative expenses, and routine plant maintenance and repairs. Total Operating Expenses Other Income (Expense): Nonoperating Income (Expense) [Abstract] Interest Income from Subsidiaries Interest Income From Subsidiaries Interest income earned on receivables from subsidiaries and eliminated in consolidation. Other Expense Other Nonoperating Income (Expense) Gain (Loss) on Indexed Debt Securities Gain (loss) on Indexed Debt Securities This item represents the net total realized and unrealized gain (loss) included in earnings f or the period related to indexed debt securities. Interest Expense to Subsidiaries Interest Expense To Subsidiaries Interest expense for debt owed to subsidiaries and eliminated in consolidation. Interest Expense Interest and Debt Expense Total Nonoperating Income (Expense) Loss Before Income Taxes, Equity in Subsidiaries Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest Income Tax Benefit Income Tax Expense (Benefit) Loss Before Equity in Subsidiaries Income Loss Before Equity In Subsidiaries Sum of operating profit (loss) and nonoperating income or expense before earnings of subsidiaries. Equity Income (Loss) of Subsidiaries Income (Loss) from Subsidiaries, Net of Tax Net Income (Loss) Net Income (Loss) Attributable to Parent Property, Plant and Equipment [Abstract] Property, Plant and Equipment Property, Plant and Equipment Disclosure [Text Block] Disclosure of Stock-Based Incentive Compensation Plans and Employee Benefit Plans [Abstract] Disclosure of Stock-Based Incentive Compensation Plans and Employee Benefit Plans [Abstract] Concentration Risk [Table] Concentration Risk [Table] Concentration Risk by Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Number of Employees, Total [Member] Number of Employees, Total [Member] Workforce Subject to Collective Bargaining Arrangements Expiring within One Year [Member] Workforce Subject to Collective Bargaining Arrangements Expiring within One Year [Member] Collective Bargaining Arrangement [Axis] Collective Bargaining Arrangement [Axis] Collective Bargaining Arrangement [Domain] Collective Bargaining Arrangement [Domain] Employees Subject To Collective Bargaining Agreements [Member] Employees Subject To Collective Bargaining Agreements [Member] Represents the employees subject to collective bargaining agreements. Concentration Risk Type [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Labor Force Concentration Risk [Member] Labor Force Concentration Risk [Member] Concentration Risk [Line Items] Concentration Risk [Line Items] Maximum Number Of Times Annual Salary Included In Severance Benefits Maximum Number Of Times Annual Salary Included In Severance Benefits Maximum number of times annual base salary included in severance benefits for certain officers in a change of control (in number of times) Concentration Risk, Percentage Concentration Risk, Percentage Organization, Consolidation and Presentation of Financial Statements [Abstract] Statement [Table] Statement [Table] Legal Entity [Axis] CERC Corp [Member] CERC Corp [Member] Another company which is controlled, directly or indirectly, by its parent. The usual condition for control is ownership of a majority (over 50%) of the outstanding voting stock. The power to control may also exist with a lesser percentage of ownership, for example, by contract, lease, agreement with other stockholders or by court decree. Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] Enable Midstream Partners [Member] Enable Midstream Partners [Member] Enable Midstream Partners, LP Statement [Line Items] Statement [Line Items] Equity Method Investment, Ownership Percentage Equity Method Investment, Ownership Percentage Statement, Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Statement of Financial Position [Abstract] ASSETS Assets [Abstract] Current Assets: Assets, Current [Abstract] Cash and cash equivalents ($264 and $290 related to VIEs, respectively) Cash and Cash Equivalents, at Carrying Value Investment in marketable securities Marketable Securities, Current Accounts receivable ($64 and $58 related to VIEs, respectively), less bad debt reserve of $20 and $26, respectively Accounts Receivable, Net, Current Accrued unbilled revenues Unbilled Receivables, Current Inventory Public Utilities, Inventory Non-trading derivative assets Derivative Asset, Current Taxes receivable Income Taxes Receivable, Current Prepaid expense and other current assets ($35 and $47 related to VIEs, respectively) Prepaid Expense and Other Assets, Current Total current assets Assets, Current Property, Plant and Equipment, net Property, Plant and Equipment, Net Other Assets: Noncurrent Assets, Other Than Property Plant and Equipment [Abstract] Noncurrent Assets, Other Than Property Plant and Equipment [Abstract] Goodwill Goodwill Regulatory assets ($2,373 and $2,738 related to VIEs, respectively) Regulatory Assets, Noncurrent Notes receivable - affiliated companies Notes Receivable, Related Parties, Noncurrent Non-trading derivative assets Derivative Asset, Noncurrent Investment in unconsolidated affiliates Equity Method Investments Other Other Assets, Noncurrent Total other assets AssetsNoncurrentOtherThanPropertyPlantAndEquipment Sum of the carrying amounts as of the balance sheet date of assets that are expected to be realized in cash, sold or consumed after one year or beyond the normal operating cycle, if longer, excluding property, plant and equipment. Total Assets Assets LIABILITIES AND SHAREHOLDERS’ EQUITY Liabilities and Equity [Abstract] Current Liabilities: Liabilities, Current [Abstract] Short-term borrowings Short-term Debt Current portion of VIE transition and system restoration bonds long-term debt Transition And System Restoration Bonds Long Term Debt Current Long-term transition and system restoration bonds are securitization bonds issued to recover qualified stranded costs and qualified storm recovery costs. This represents the current portion. Indexed debt Indexed Debt Current Current portion of other long-term debt Other Long-term Debt, Current Indexed debt securities derivative Indexed debt securities derivative Accounts payable Accounts Payable, Current Taxes accrued Taxes Payable, Current Interest accrued Interest Payable, Current Non-trading derivative liabilities Derivative Liability, Current Other Other Liabilities, Current Total current liabilities Liabilities, Current Other Liabilities: Liabilities, Noncurrent [Abstract] Deferred income taxes, net Deferred Tax Liabilities, Net, Noncurrent Non-trading derivative liabilities Derivative Liability, Noncurrent Benefit obligations Regulatory liabilities Regulatory Liability, Noncurrent Other Other Liabilities, Noncurrent Total non-current liabilities Liabilities, Other than Long-term Debt, Noncurrent Long-term Debt: Long-term Debt, Excluding Current Maturities [Abstract] VIE transition and system restoration bonds Transition And System Restoration Bonds Long Term Debt Non Current Carrying value as of the balance sheet date of transition and system restoration bond debt (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Other long-term debt Other Long-term Debt, Noncurrent Total long-term debt Long-term Debt, Excluding Current Maturities Commitments and Contingencies (Note 14) Commitments and Contingencies Shareholders’ Equity Stockholders' Equity Attributable to Parent Total Liabilities and Shareholders’ Equity Liabilities and Equity Quarterly Financial Information Disclosure [Abstract] Quarterly Financial Data Schedule of Quarterly Financial Information [Table Text Block] Indexed Debt Securities [Abstract] Indexed Debt Securities [Abstract] Summarized Financial Information on Investment in Time Warner Securities and Indexed Debt Security Obligation Schedule of Indexed Debt Securities and Marketable Securities [Table Text Block] Schedule of Indexed Debt Securities and Marketable Securities [Table Text Block] Derivative Instruments and Hedging Activities Disclosure [Abstract] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] External Credit Rating by Grouping [Axis] External Credit Rating by Grouping [Axis] External Credit Rating by Grouping [Domain] External Credit Rating by Grouping [Domain] External Credit Rating, Investment Grade [Member] External Credit Rating, Investment Grade [Member] Derivative, by Nature [Axis] Derivative, by Nature [Axis] Derivative, Name [Domain] Derivative, Name [Domain] Swap [Member] Swap [Member] Forward Contracts [Member] Forward Contracts [Member] Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] Energy Marketers [Member] Energy Marketers [Member] Derivative asset amounts associated with energy marketers. Retail End Users [Member] Retail End Users [Member] Derivative asset amounts associated with retail end users. Position [Axis] Position [Axis] Position [Domain] Position [Domain] Long [Member] Long [Member] Derivative Instrument [Axis] Derivative Contract [Domain] Energy Related Derivative [Member] Energy Related Derivative [Member] IDS Derivative [Member] IDS Derivative [Member] Derivative instrument related to indexed debt securities Hedging Designation [Axis] Hedging Designation [Domain] Derivatives Not Designated as Hedging Instruments [Member] Not Designated as Hedging Instrument [Member] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Current Assets [Member] Line item in the statement of financial position in which the fair value amounts of the derivative instruments are included. Other Noncurrent Assets [Member] Other Noncurrent Assets [Member] Current Liabilities [Member] Current Liabilities [Member] Line item in the statement of financial position in which the fair value amounts of the derivative instruments are included. Other Noncurrent Liabilities [Member] Other Noncurrent Liabilities [Member] Income Statement Location [Axis] Income Statement Location [Axis] Derivative Instruments, Gain (Loss) by Income Statement Location [Domain] Income Statement Location [Domain] Gains (Losses) in Revenue [Member] Sales [Member] Gains (Losses) in Expense: Natural Gas [Member] Cost of Sales [Member] Nonoperating Income (Expense) [Member] Nonoperating Income (Expense) [Member] Derivative [Line Items] Derivative [Line Items] Weather Hedge, Bilateral Cap Amount Weather Hedge, Bilateral Cap Amount Represents amount of bilateral cap related to weather hedges. Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract] Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract] Derivative Asset, Fair Value, Gross Asset Derivative Asset, Fair Value, Gross Asset Derivative Liability, Fair Value, Gross Liability Derivative Liability, Fair Value, Gross Liability Derivative, Nonmonetary Notional Amount, Volume Derivative, Nonmonetary Notional Amount, Volume Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset Natural gas derivatives (2) Derivative Asset Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset Derivative Liability Derivative Liability Derivative Assets (Liabilities), at Fair Value, Net Derivative Assets (Liabilities), at Fair Value, Net Collateral netting Collateral Netting Amount of collateral netted against derivative contracts. Derivative, Fair Value, Net Derivative, Fair Value, Net Derivative, fair value, offsets, net Derivative, Fair Value, Offsets, Net Total of gross amounts offset, net. Income Statement Impact of Derivative Activity [Abstract] Income Statement Impact of Derivative Activity [Abstract] Income Statement Impact of Derivative Activity [Abstract] Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net Derivative, Credit Risk Related Contingent Features [Abstract] Derivative, Credit Risk Related Contingent Features [Abstract] Total fair value of the derivative instruments that contain credit risk contingent features that are in a net liability position Derivative, Net Liability Position, Aggregate Fair Value The aggregate fair value of assets already posted as collateral Collateral Already Posted, Aggregate Fair Value Credit Risk Contingent Features assets Additional Collateral, Aggregate Fair Value Credit Risk Derivatives, at Fair Value, Net [Abstract] Total Credit Risk Derivative Assets, at Fair Value Income Tax Disclosure [Abstract] Other Tax Carryforward [Table] Tax Credit Carryforward [Table] Tax Period [Axis] Tax Period [Axis] Tax Period [Domain] Tax Period [Domain] Latest Tax Year [Member] Latest Tax Year [Member] Earliest Tax Year [Member] Earliest Tax Year [Member] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] Internal Revenue Service (IRS) [Member] Internal Revenue Service (IRS) [Member] State and Local Jurisdiction [Member] State and Local Jurisdiction [Member] Other Tax Carryforward Data by Item [Axis] Tax Credit Carryforward [Axis] Other Tax Carryforward, Name [Domain] Tax Credit Carryforward, Name [Domain] Alternative Minimum Tax Credit Carryforward [Member] Alternative Minimum Tax Credit Carryforward [Member] Alternative Minimum Tax Credit Carryforward [Member] Capital Loss Carryforward [Member] Capital Loss Carryforward [Member] Charitable Contribution Carryforward [Member] Charitable Contribution Carryforward [Member] Charitable Contribution Carryforward [Member] General Business Tax Credit Carryforward [Member] General Business Tax Credit Carryforward [Member] Other Tax Carryforward [Line Items] Tax Credit Carryforward [Line Items] Loss Contingency, Pending Claims, Number Loss Contingency, Pending Claims, Number Current income tax expense (benefit): Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Federal Current Federal Tax Expense (Benefit) State Current State and Local Tax Expense (Benefit) Total current expense (benefit) Current Income Tax Expense (Benefit) Deferred income tax expense (benefit): Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Federal Deferred Federal Income Tax Expense (Benefit) State Deferred State and Local Income Tax Expense (Benefit) Total deferred expense (benefit) Deferred Income Tax Expense (Benefit) Total income tax expense (benefit) Income tax reconciliation [Abstract] Effective Income Tax Rate Reconciliation, Amount [Abstract] Income (loss) before income taxes Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest Federal statutory income tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Expected federal income tax expense (benefit) Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount Increase (decrease) in tax expense resulting from: Change In Tax Expense Abstract State income tax expense, net of federal income tax Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount Tax effect related to the formation of Enable Increase (decrease) in tax expense due to formation of midstream partnership Increase (decrease) in tax expense due to formation of midstream partnership Decrease in settled and uncertain income tax positions Income Tax Reconciliation Tax Settlements And Uncertain Income Tax Positions The sum of the differences between total income tax expense (benefit) as reported in the Income Statement and the expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to all income tax settlements for the period and changes in uncertain income tax positions. Tax basis balance sheet adjustments Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability Other, net Effective Income Tax Rate Reconciliation, Other Reconciling Items, Amount Total Income Tax Reconciliation Change In Tax Expense Represents the increase (decrease) in tax expense resulting from various reconciling items. Total income tax expense (benefit) Effective tax rate (in hundredths) Effective Income Tax Rate Reconciliation, Percent Increase (Decrease) in Deferred Income Taxes Increase (Decrease) in Deferred Income Taxes Increase (Decrease) in Accrued Taxes Payable Increase (Decrease) in Income Taxes Payable Increase (Decrease) in Income Taxes Increase (Decrease) in Income Taxes Deferred Tax Liabilities, Goodwill and Intangible Assets Deferred Tax Liabilities, Goodwill and Intangible Assets Income tax expense (benefit) resulting from IRS settlement Tax Adjustments, Settlements, and Unusual Provisions Deferred tax assets: Deferred Tax Assets, Net [Abstract] Benefits and compensation Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits Loss and credit carryforwards Deferred Tax Assets Loss And Credit Tax Carryforwards The tax effect as of the balance sheet date of the amount of future tax deductions arising from loss and credit tax carryforwards and which can only be utilized if sufficient tax-basis income is generated in future periods and providing tax laws continue to allow utilization. Asset retirement obligations Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Asset Retirement Obligations Other Deferred Tax Assets Noncurrent Other The tax effect as of the balance sheet date of the amount of estimated future tax deductions arising from other temporary differences not otherwise specified in the taxonomy that are not expected to be resolved within 12 months of the balance sheet date. Valuation allowance Deferred Tax Assets, Valuation Allowance Deferred Tax Assets, Net of Valuation Allowance Deferred Tax Assets, Net of Valuation Allowance Deferred tax liabilities: Deferred Tax Liabilities, Gross [Abstract] Property, plant, and equipment Deferred Tax Liabilities, Property, Plant and Equipment Investment in unconsolidated affiliates Deferred Tax Liabilities, Investment in Noncontrolled Affiliates Regulatory assets/liabilities, net Deferred Tax Liabilities, Regulatory Assets and Liabilities Investment in marketable securities and indexed debt Deferred Tax Liabilities, Investments Indexed debt securities derivative Deferred Tax Liabilities, Indexed Debt Securities Derivative Amount of deferred tax liability attributable to taxable temporary differences from indexed debt securities derivative Other Deferred Tax Liabilities Noncurrent Other The cumulative amount of the estimated future tax effects attributable to other temporary differences not otherwise specified in this taxonomy that are expected to reverse more than 12 months after the balance sheet date. Deferred Tax Liabilities, Gross Deferred Tax Liabilities, Gross Deferred Tax Liabilities, Net Deferred Tax Liabilities, Net Operating Loss Carryforwards Operating Loss Carryforwards Tax Credit Carryforward, Expiration Date Operating Loss Carryforwards, Expiration Date Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax Tax Credit Carryforward, Amount Tax Credit Carryforward, Expiration Date Tax Credit Carryforward, Expiration Date Operating Loss Carryforwards Valuation Allowance Net of Federal Tax Operating Loss Carryforwards Valuation Allowance Net of Federal Tax The portion of the valuation allowance pertaining to the deferred tax asset representing potential future taxable deductions from state net operating loss carryforwards net of federal tax for which it is more likely than not that a tax benefit will not be realized. Balance, beginning of year Unrecognized tax expense The gross amount of unrecognized tax expense pertaining to uncertain tax positions taken in tax returns as of the balance sheet date. Tax Positions related to prior years: Unrecognized Tax Benefits Prior Year Tax Positions Abstract Reductions Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions Tax Positions related to current year: Unrecognized Tax Benefits Current Year Tax Positions Abstract Settlements Unrecognized Tax Benefits, Increase Resulting from Settlements with Taxing Authorities Balance, end of year Unrecognized Tax Benefits Income Tax Expense (Benefit) Related To Interest On Income Tax Positions Income Tax Expense Benefit Related To Interest On Income Tax Positions Represents the amount of income tax expense (benefit) recognized in the period related to interest on income tax positions. Fair Value Disclosures [Abstract] Fair Value, Assets Measured on a Recurring Basis 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 Using Significant Unobservable Inputs Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Estimated Fair Value of Financial Instruments, Debt Instruments Fair Value, by Balance Sheet Grouping [Table Text Block] Valuation and Qualifying Accounts [Abstract] Valuation and Qualifying Accounts Disclosure [Table] Valuation and Qualifying Accounts Disclosure [Table] Valuation Allowances and Reserves Type [Axis] Valuation Allowances and Reserves Type [Axis] Valuation Allowances and Reserves [Domain] Valuation Allowances and Reserves [Domain] Uncollectible accounts receivable [Member] Allowance for Trade Receivables [Member] Deferred tax asset valuation allowance [Member] Valuation Allowance of Deferred Tax Assets [Member] Valuation and Qualifying Accounts Disclosure [Line Items] Valuation and Qualifying Accounts Disclosure [Line Items] Movement in Valuation Allowances and Reserves [Roll Forward] Movement in Valuation Allowances and Reserves [Roll Forward] Balance at Beginning of Period Valuation Allowances and Reserves, Balance Additions Charged to Income Valuation Allowances and Reserves, Charged to Cost and Expense Valuation Allowances and Reserves, Addition to Other Accounts Valuation Allowances and Reserves, Addition to Other Accounts Total of allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value at its carrying value) or that reflect a liability established to represent expected future costs, added to accounts other than costs and expenses in a given period. Additions Charged to Other Accounts Valuation Allowances and Reserves, Charged to Other Accounts Deductions From Reserves Valuation Allowances and Reserves, Deductions Balance at End of Period Debt Disclosure [Abstract] Schedule of Short-term Borrowings and Long-term Debt Schedule of Debt [Table Text Block] Schedule of Revolving Credit Facilities and Utilization of Such Facilities Schedule of Line of Credit Facilities [Table Text Block] Segment Reporting [Abstract] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Products and Services [Axis] Products and Services [Axis] Products and Services [Domain] Products and Services [Domain] Electric Delivery [Member] Electric Delivery [Member] Represents revenues from electric transmission and distribution sales Retail Gas Sales [Member] Retail Gas Sales [Member] Represents revenue from retail gas sales Wholesale Gas Sales [Member] Wholesale Gas Sales [Member] Represents revenue from wholesale gas sales Gas Transportation and Processing [Member] Gas Transportation and Processing [Member] Represents revenues from gas transportation and processing Energy Products Or Services [Member] Energy Products Or Services [Member] Represents revenue from energy products and services Revenues by Products and Services: Product And Service Abstract Each product and service of an entity by various financial or nonfinancial attributes. Revenues Income Taxes Income Tax Disclosure [Text Block] Condensed Cash Flow Statement [Table] Condensed Cash Flow Statement [Table] Entity [Domain] Condensed Cash Flow Statements, Captions [Line Items] Condensed Cash Flow Statements, Captions [Line Items] Cash Flows from Operating Activities: Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Net income (loss) Non-cash items included in net income (loss): Adjustments, Noncash Items, to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Equity (income) loss of subsidiaries Deferred income tax expense Amortization of debt issuance costs Amortization of Financing Costs (Gain) loss on indexed debt securities Unrealized Loss (Gain) on Indexed Debt Securities Unrealized Loss (Gain) on Indexed Debt Securities. Changes in working capital: Increase (Decrease) in Operating Capital [Abstract] Accounts receivable/(payable) from subsidiaries, net Net Change In Accounts Receivable Payable From Subsidiaries The net change during the reporting period in accounts receivable (payable) from subsidiaries not otherwise defined in the taxonomy. Accounts payable Increase (Decrease) in Accounts Payable Other current assets Increase (Decrease) in Other Current Assets Other current liabilities Increase (Decrease) in Other Current Liabilities Common stock dividends received from subsidiaries Cash Dividends Paid to Parent Company by Consolidated Subsidiaries Other Other Operating Activities, Cash Flow Statement Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities, Continuing Operations Investing Activities: Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Decrease (increase) in notes receivable from subsidiaries Proceeds from Collection of (Payments to Fund) Long-term Loans to Related Parties Net cash provided by (used in) investing activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations Financing Activities: Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Proceeds from commercial paper, net Proceeds from (Repayments of) Commercial Paper Payments of long-term debt Repayments of Long-term Debt Debt issuance costs Payments of Debt Issuance Costs Common stock dividends paid Payments of Ordinary Dividends, Common Stock Proceeds from issuance of common stock, net Proceeds from Issuance of Common Stock Increase (decrease) in notes payable to subsidiaries Proceeds from (Repayments of) Related Party Debt Redemption of indexed debt securities Redemption of Indexed Debt Securities Redemption of Indexed Debt Securities Distribution to ZENS holders Distribution To ZENS Holders This represents a distribution to ZENS holders during the period in accordance with the terms of the ZENS. Other Proceeds from (Payments for) Other Financing Activities Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations Net Decrease in Cash and Cash Equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and Cash Equivalents at Beginning of Year Cash and Cash Equivalents at End of Year Schedule II - Valuation and Qualifying Accounts Disclosure Schedule of Valuation and Qualifying Accounts Disclosure [Text Block] Accounting Policies [Abstract] Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Document and Entity Information [Abstract] Document and Entity Information [Abstract] Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Voluntary Filers Entity Current Reporting Status Entity Current Reporting Status Entity Public Float Entity Public Float Regulated Operations [Abstract] Regulatory Matters Public Utilities Disclosure [Text Block] Fair Value of Derivative Instruments Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Offsetting of Natural Gas Derivative Assets and Liabilities [Table Text Block] Derivative Instruments, Offsetting Assets and Liabilities [Table Text Block] Tabular disclosure of derivative assets and liabilities that are subject to offsetting, including master netting arrangements. Income Statement Impact of Derivative Activity Derivative Instruments, Gain (Loss) [Table Text Block] Credit Quality of Counterparties Disclosure of Credit Derivatives [Table Text Block] Income Tax Expense Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Reconciliation of Expected Federal Income Tax Expense to Actual Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Tax Assets and Liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Rollforward of Unrecognized Tax Benefits Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block] Commitments and Contingencies Disclosure [Abstract] Long-term Purchase Commitment [Table] Long-term Purchase Commitment [Table] Category of Item Purchased [Axis] Category of Item Purchased [Axis] Long-term Purchase Commitment, Category of Item Purchased [Domain] Long-term Purchase Commitment, Category of Item Purchased [Domain] Natural Gas Supply Commitments [Member] Natural Gas Supply Commitments [Member] Represents natural gas contracts having various quantity requirements and durations classified as "normal purchases contracts" and natural gas transportation contracts. These contracts do not meet the definition of a derivative. Environmental Remediation Site [Axis] Environmental Remediation Site [Axis] Environmental Remediation Site [Domain] Environmental Remediation Site [Domain] Minnesota Service Territory [Member] Minnesota Service Territory [Member] Represents the areas in Minnesota serviced by CERC Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Domain] Guarantor Obligations, Nature [Domain] GenOn Demand Charges Transportation Contracts [Member] GenOn Demand Charges Transportation Contracts [Member] Represents guarantees for demand charges under certain gas transportation agreements CenterPoint Midstream Guarantees [Member] CenterPoint Midstream Guarantees [Member] Represents guarantees with respect to the performance of certain obligations under long-term gas gathering and treating agreements. Enable Guaranteed Senior Notes [Member] Enable Guaranteed Senior Notes [Member] Represents a guarantee of collection of Enable's senior notes due 2019 and 2024 Litigation Case [Axis] Litigation Case [Axis] Litigation Case [Domain] Litigation Case [Domain] Gas Market Manipulation Cases [Member] Gas Market Manipulation Cases [Member] Represents lawsuits filed against numerous gas market participants in a number of federal and western state courts in connections with the operation of the natural gas markets in 2000-2002. Long-term Purchase Commitment [Line Items] Long-term Purchase Commitment [Line Items] 2016 Purchase Obligation, Due in Next Twelve Months 2017 Purchase Obligation, Due in Second Year 2018 Purchase Obligation, Due in Third Year 2019 Purchase Obligation, Due in Fourth Year 2020 Purchase Obligation, Due in Fifth Year After 2020 Purchase Obligation, Due after Fifth Year Operating Leases, Future Minimum Payments Due [Abstract] Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] 2016 Operating Leases, Future Minimum Payments Due, Next Twelve Months 2017 Operating Leases, Future Minimum Payments, Due in Two Years 2018 Operating Leases, Future Minimum Payments, Due in Three Years 2019 Operating Leases, Future Minimum Payments, Due in Four Years 2020 Operating Leases, Future Minimum Payments, Due in Five Years 2021 and beyond Operating Leases, Future Minimum Payments, Due Thereafter Total Operating Leases, Future Minimum Payments Due Total lease expense for all operating leases Operating Leases, Rent Expense Legal Environmental And Other Regulatory Matters Legal Matters Gas Market Manipulation Cases Abstract Loss Contingency, Information about Litigation Matters [Abstract] Amount accrued for remediation of Minnesota sites (in number of sites) Accrual for Environmental Loss Contingencies Minimum estimated remediation costs for the Minnesota sites Site Contingency Loss Exposure Estimate of the reasonably possible loss exposure at an individual site. Site Contingency, Years to Resolve Contingency Site Contingency, Years to Resolve Contingency This represents the estimated years necessary to resolve the contingency. Undiscounted maximum potential payout of demand charges Guarantor Obligations, Maximum Exposure, Undiscounted Schedule of Condensed Financial Statements [Table] Condensed Financial Statements [Table] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Senior Notes Senior Notes Due Range 1 [Member] Senior Notes Due Range 1 [Member] Long term Debt Excluding Indexed Debt Securities [Member] Long term Debt Excluding Indexed Debt Securities [Member] Represents long term debt excluding indexed debt securities. Pollution control bonds Bonds Pollution Control Due Range 1 [Member] Bonds Pollution Control Due Range 1 [Member] Municipal Bonds [Member] Municipal Bonds [Member] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Revolving Credit Facility [Member] Revolving Credit Facility [Member] Letter of Credit [Member] Letter of Credit [Member] Commercial Paper [Member] Commercial Paper [Member] Line of Credit [Member] Line of Credit [Member] CenterPoint Houston [Member] CenterPoint Houston [Member] Another company which is controlled, directly or indirectly, by its parent. The usual condition for control is ownership of a majority (over 50%) of the outstanding voting stock. The power to control may also exist with a lesser percentage of ownership, for example, by contract, lease, agreement with other stockholders or by court decree. Condensed Financial Statements, Captions [Line Items] Condensed Financial Statements, Captions [Line Items] Percentage on limitation of debt to total capitalization under covenant (in hundredths) Percentage on limitation of debt to total capitalization under covenant (in hundredths) Percentage on limitation of debt to total capitalization under covenant. Unamortized Debt Issuance Expense Unamortized Debt Issuance Expense Deferred Income Tax Liability, reclassified to noncurrent Deferred Income Tax Liability, Reclassified To Noncurrent Represents the amount of deferred income tax liability reclassified from current to non-current due to ASU 2015-17. Extinguishment of Debt, Amount Extinguishment of Debt, Amount Debt Instrument, Interest Rate, Stated Percentage Debt Instrument, Interest Rate, Stated Percentage Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum Maximum amount of credit facility Line of Credit Facility, Maximum Borrowing Capacity Retirement Of Bonds Held For Remarketing Retirement Of Bonds Held For Remarketing Represents the amount of bonds retired during the period that had been held by the company for remarketing. Long-term Line of Credit Long-term Line of Credit Debt, Weighted Average Interest Rate Debt, Weighted Average Interest Rate Notes to Financial Statements of Parent, Long-Term Debt: Notes To Financial Statements Of Parent Long Term Debt [Abstract] Debt Maturities in 2016 Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months Debt Maturities in 2017 Long-term Debt, Maturities, Repayments of Principal in Year Two Debt Maturities in 2018 Long-term Debt, Maturities, Repayments of Principal in Year Three Debt Maturities in 2019 Long-term Debt, Maturities, Repayments of Principal in Year Four Debt Maturities in 2020 Long-term Debt, Maturities, Repayments of Principal in Year Five Debt Instrument, Basis Spread on Variable Rate Debt Instrument, Basis Spread on Variable Rate Ratio of Indebtedness to Net Capital Ratio of Indebtedness to Net Capital Percentage on limitation of debt to total capitalization under covenant amended (in hundredths) Percentage on limitation of debt to total capitalization under covenant amended (in hundredths) Temporary increased percentage on limitation of debt to total capitalization under covenant (in hundredths) Restoration Cost Expected Cost Restoration Cost Expected Cost The minimum amount of estimated restoration cost in a calendar year in order for a temporary increase in debt to EBITDA covenant Consecutive Period for System Restoration Costs to Exceed $100 million (in months) Consecutive Period for System Restoration Costs to Exceed $100 million (in months) Consecutive Period for System Restoration Costs to Exceed $100 million (in months) Guarantor Obligations, Maximum Exposure, Undiscounted Statements of Consolidated Comprehensive Income Statement of Comprehensive Income [Abstract] Net income (loss) Other comprehensive income: Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Adjustment to pension and other postretirement plans (net of tax of $12, $5 and $25, respectively) Reclassification of deferred loss from cash flow hedges realized in net income (net of tax) Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax Other comprehensive income Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Comprehensive income (loss) Comprehensive Income (Loss), Net of Tax, Attributable to Parent Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs, by Report Line [Axis] Income Statement Location [Domain] Operation And Maintenance Expense Member Operation And Maintenance Expense Member Amount of share-based compensation cost reported in the period, allocated to operations and maintenance expense. Operations and maintenance expense are the costs associated with normal operations, including general and administrative expenses, and routine plant maintenance and repairs. Schedule of Share-based Compensation Arrangement by Share-based Payment Award, Award Type and Plan Name [Axis] Award Type [Axis] Award Type [Domain] Equity Award [Domain] Performance Shares [Member] Performance Shares [Member] Stock Awards [Member] Stock Awards Member Stock awards within the entity's long-term stock incentive plan. Performance and Stock Awards [Member] Performance and Stock Awards [Member] Performance and Stock Awards [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Shares authorized for issuance under long-term incentive plans (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized Vesting period (in years) Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Dividends declared during the vesting period (in dollars per share) Minimum Total Common Stock Dividends Declared During Three Year Vesting Period Represents the minimum total common stock dividend that must be declared during the three year vesting period for stock awards Employee Service Share-based Compensation, Aggregate Disclosures [Abstract] Employee Service Share-based Compensation, Aggregate Disclosures [Abstract] LTIP compensation expense Allocated Share-based Compensation Expense Income tax benefit recognized related to LTIPs Employee Service Share-based Compensation, Tax Benefit from Compensation Expense Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount Actual tax benefit realized for tax deductions related to LTIPs Employee Service Share-based Compensation, Tax Benefit Realized from Exercise of Stock Options Summary of changes in shares outstanding under all long-term incentive plans [Rollforward] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Changes in shares outstanding under all long-term incentive plans, additional disclosures [Abstract] Changes In Shares Outstanding Under Long Term Incentive Plans Additional Disclosures Abstract Cash received from options exercised Employee Service Share-based Compensation, Cash Received from Exercise of Stock Options Summary of nonvested shares [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Nonvested, beginning of period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Forfeited or cancelled (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Vested and released to participants (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Nonvested, end of period (in shares) Weighted average grant date fair value, nonvested, beginning of period (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Weighted average grant date fair values of awards granted (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Weighted average grant date fair value, forfeited or cancelled (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Weighted average grant date fair value, vested and released to participants (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Weighted average grant date fair value, nonvested, end of period (in dollars per share) Remaining average contractual life of nonvested shares outstanding (in years) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Remaining Contractual Terms Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Nonvested Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Nonvested valuation data [Abstract] valuation data [Abstract] valuation data [Abstract] Total intrinsic value of stock options exercised in the period Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Vested Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Vested Total grant date fair values of performance and stock awards which vested during the period Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Grant Date Fair Value The total fair values as of grant dates pertaining to share-based award plans other than stock option plans for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares, other instruments, or cash in accordance with the terms of the arrangement. Unrecognized compensation cost related to non-vested performance and stock awards Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Weighted average period of recognition (in years) Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Statement of Stockholders' Equity [Abstract] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Preference Stock [Member] Preference Stock [Member] Preferred Stock [Member] Preferred Stock [Member] Additional Paid-in Capital [Member] Additional Paid-in Capital [Member] Retained Earnings [Member] Retained Earnings [Member] Adjustment to pension and postretirement plans [Member] Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Net deferred loss from cash flow hedges [Member] Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] Total accumulated other comprehensive loss, end of year [Member] AOCI Attributable to Parent [Member] Shares, Outstanding Shares, Outstanding Increase (Decrease) in Stockholders' Equity [Roll Forward] Balance Issuance related to benefit and investment plans Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures Issuance related to benefit and investment plans (in shares) Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures Common stock dividends Dividends, Common Stock Balance Shares, Outstanding Goodwill and Intangible Assets Disclosure [Abstract] Schedule of Goodwill [Table] Natural Gas Distribution [Member] Natural Gas Distribution [Member] Segment information for the Natural Gas Distribution segment which consists of intrastate natural gas sales to, and natural gas transportation and distribution for, residential, commercial, industrial and institutional customers. Energy Services [Member] Energy Services [Member] Segment information for the Energy Services segment which offers variable and fixed price physical natural gas supplies primarily to commercial and industrial customers and electric and gas utilities. Other [Member] Corporate and Other [Member] Goodwill [Line Items] Goodwill [Line Items] Goodwill Accumulated Goodwill Impairment Charge Goodwill, Impaired, Accumulated Impairment Loss Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Defined Benefit Plans Adjustment [Member] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Schedule of Nonvested Performance-based Units Activity [Table Text Block] Schedule of Nonvested Performance-based Units Activity [Table Text Block] Schedule of Nonvested Share Activity [Table Text Block] Schedule of Nonvested Share Activity [Table Text Block] Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value [Table Text Block] Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value [Table Text Block] Schedule of Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Grant Date Intrinsic Value [Table Text Block] Schedule of Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Grant Date Intrinsic Value [Table Text Block] Schedule of Net Benefit Costs [Table Text Block] Schedule of Net Benefit Costs [Table Text Block] Schedule of Assumptions Used [Table Text Block] Schedule of Assumptions Used [Table Text Block] Schedule of Net Pension and Post-retirement Benefit Costs Schedule of Defined Benefit Plans Disclosures [Table Text Block] Schedule of Defined Benefit Plan Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block] Schedule of Defined Benefit Plan Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block] Schedule of Amounts in Accumulated Other Comprehensive Income (Loss) to be Recognized over Next Fiscal Year [Table Text Block] Schedule of Amounts in Accumulated Other Comprehensive Income (Loss) to be Recognized over Next Fiscal Year [Table Text Block] Schedule of Accumulated Benefit Obligations in Excess of Fair Value of Plan Assets [Table Text Block] Schedule of Accumulated Benefit Obligations in Excess of Fair Value of Plan Assets [Table Text Block] Schedule of a One-percent Point Change in the Assumed Health Care Cost Trend Rates Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates [Table Text Block] Target Allocation of Plan Assets [Table Text Block] Target Allocation of Plan Assets [Table Text Block] Tabular presentation of the weighted average allocation targets maintained Schedule of Allocation of Plan Assets [Table Text Block] Schedule of Allocation of Plan Assets [Table Text Block] Schedule of Expected Benefit Payments [Table Text Block] Schedule of Expected Benefit Payments [Table Text Block] Short-Term Borrowings and Long-Term Debt [Table] Short-Term Borrowings and Long-Term Debt [Table] Short-Term Borrowings and Long-Term Debt [Table] Short-term Debt, Type [Axis] Short-term Debt, Type [Axis] Short-term Debt, Type [Domain] Short-term Debt, Type [Domain] Product Financing Arrangement [Member] Product Financing Arrangement [Member] ZENS (2) Subordinated Debt ZENS Member Issued debt obligation as zero-premium exchangeable subordinated notes. Obligation is bifurcated between a debt component and an embedded derivative component. Exchangeable for cash at any time at the option of the holder, and as such are classified as a current portion of long-term debt. Senior notes 5.95% to 6.85% due 2017 to 2018 Pollution control bonds 5.05% to 5.125% due 2018 to 2028 (3) Commercial paper (4) Bank Loans Bank Loan Obligations [Member] First mortgage bonds 9.15% due 2021 Bonds First Mortgage Due2021 Member A loan secured by real property that has a first (highest) lien on such property in the event of default by the borrower. General mortgage bonds 2.25% to 6.95% due 2022 to 2044 Bonds General Mortgage Due Range 1 [Member] Bonds General Mortgage Due Range 1 [Member] System restoration bonds 3.46% to 4.243% due 2018 to 2022 Bonds System Restoration Due Range 1 [Member] Bonds System Restoration Due Range 1 [Member] Transition bonds 0.901% to 5.302% due 2017 to 2024 Bonds Transition Due Range 1 Member [Member] Bonds Transition Due Range 1 Member [Member] Senior notes 4.50% to 6.625% due 2016 to 2041 Senior Notes Due Range 2 [Member] Senior Notes Due Range 2 [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum (in hundredths) Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum (in hundredths) Short term borrowings: Short term debt [Abstract] Short term debt [Abstract] Total short-term borrowings Long-term debt: Long-term Debt, by Current and Noncurrent [Abstract] Long-Term Long-term Debt, Gross, Noncurrent Amount of long-term debt, noncurrent portion, before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer. Current Long-term Debt, Gross, Current Amount of long-term debt scheduled to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations. Capital Lease Obligations, Noncurrent Capital Lease Obligations, Noncurrent Capital Lease Obligations, Current Capital Lease Obligations, Current Unamortized Discount (Premium), Net Debt Instrument, Unamortized Discount (Premium), Net Long-term Debt, Excluding Current Maturities Long-term Debt, Current Maturities Long-term Debt, Current Maturities Debt, Current Debt, Current Amount of debt secured by general mortgage bonds Secured Debt Schedule of Regulatory Assets and Liabilities [Table] Schedule Of Regulatory Assets And Liabilities [Table] A table of assets and liabilities that are created when regulatory agencies permit public utilities to defer certain costs and the recognition of certain revenues that are included in rate-setting to the balance sheet. Regulatory Asset [Axis] Regulatory Asset [Axis] Regulatory Asset [Domain] Regulatory Asset [Domain] Pension and Other Postretirement Plans Costs [Member] Pension and Other Postretirement Plans Costs [Member] Securitized regulatory assets Securitized Regulatory Asset Member Carrying value of the regulatory assets that represent capitalized stranded costs and system restoration costs that have been securitized (financed with debt). Unamortized loss on reacquired debt Loss on Reacquired Debt [Member] Pension and postretirement-related regulatory asset (2) Pension And Postretirement Related Regulatory Asset [Member] Unrecognized costs associated with operations that recover pension and postretirement costs in rates and net periodic pension costs deferred according to actions of the regulator. Other Regulatory Assets (Liabilities) [Member] Other Regulatory Assets (Liabilities) [Member] Regulatory Liability [Axis] Regulatory Liability [Axis] Regulatory Liability [Domain] Regulatory Liability [Domain] Removal Costs [Member] Removal Costs [Member] Schedule of Regulatory Assets and Liabilities [Line Items] Schedule Of Regulatory Assets And Liabilities [Line Items] -- None. No documentation exists for this element. -- Unrecognized equity return (1) Unrecognized Equity Return Represents the balance of the allowed return on equity that has been deferred and recorded on the balance sheet Total regulatory assets Total regulatory assets and liabilities, net Net Regulatory Assets Amount of allowed equity return on the true-up balance that was recognized in the period Amount Of Allowed Equity Return Recognized In Period Amount of allowed equity return on the true-up balance that was recognized in the period Remaining amounts of regulatory assets for which no return on investment during recovery period is provided Remaining Amounts of Regulatory Assets for which No Return on Investment During Recovery Period is Provided Condensed Statement of Comprehensive Income [Table] Condensed Statement of Comprehensive Income [Table] Condensed Statement of Income Captions [Line Items] Condensed Statement of Income Captions [Line Items] Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax Subsequent Events [Abstract] Subsequent Event [Table] Subsequent Event [Table] Series A Preferred Stock [Member] Series A Preferred Stock [Member] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event [Member] Subsequent Event [Member] Subsequent Event [Line Items] Subsequent Event [Line Items] Dividends Payable, Date Declared Dividends Payable, Date Declared Quarterly Cash Dividend Declared Common Stock, Dividends, Per Share, Declared Dividends Payable, Date to be Paid Dividends Payable, Date to be Paid Dividends Payable, Date of Record Dividends Payable, Date of Record Expected Cash Distribution Proceeds from Equity Method Investment, Dividends or Distributions Number of Preferred Units Purchased Purchase of Preferred Units, Number of Units Purchased Represents the number of preferred units purchased in private placement. Interest Rate on Preferred Units Investment Interest Rate Purchase Price Per Preferred Unit Purchase of Preferred Units, Price Per Unit Per unit cash purchase price for each preferred unit purchased in a private placement. Redemption of Debt by Enable Business Acquisition, Name of Acquired Entity Business Acquisition, Name of Acquired Entity Amount to be paid to purchase Continuum Payments to Acquire Businesses, Gross Adjustment to pension and other postretirement plans (net of tax of $12, $5 and $25 respectively Stockholders' Equity Note [Abstract] Capital stock shares authorized (in shares) Capital Stock Shares Authorized The maximum number of capital shares permitted to be issued by an entity's charter and bylaws. Common stock shares authorized (in shares) Common Stock, Shares Authorized Common stock shares par value (in dollars per share) Common Stock, Par or Stated Value Per Share Cumulative preferred stock shares authorized (in shares) Preferred Stock, Shares Authorized Cumulative preferred stock par value (in dollars per share) Preferred Stock, Par or Stated Value Per Share Dividends Declared Per Share Retained Earnings, Undistributed Earnings from Equity Method Investees Retained Earnings, Undistributed Earnings from Equity Method Investees Fair Value Measurements Fair Value Disclosures [Text Block] Schedule of Property, Plant and Equipment Property, Plant and Equipment [Table Text Block] Depreciation and Amortization Depreciation And Amortization [Table Text Block] This element can be used to encapsulate the entire disclosure for depreciation and amortization expense for the period. Asset Retirement Obligation Schedule of Change in Asset Retirement Obligation [Table Text Block] Other comprehensive income Comprehensive income (loss) Preferred Stock, Shares Outstanding Preferred Stock, Shares Outstanding Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Schedule I - Condensed Financial Information of Centerpoint Energy, Inc. (Parent Company) Condensed Financial Information of Parent Company Only Disclosure [Text Block] Stock-Based Incentive Compensation Plans and Employee Benefit Plans Pension And Postretirement Benefits And Share Based Payments Disclosure Text Block Description containing the entire pension and other postretirement benefits and share-based compensation disclosures as a single block of text. Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Long term Debt Excluding ZENS [Member] Long term Debt Excluding ZENS [Member] Represents balances related to long-term debt excluding ZENS Transition And System Restoration Bonds [Member] Transition And System Restoration Bonds [Member] Represents the amount of transition and system restoration bonds maturing. Line of Credit Facility [Abstract] Line of Credit Facility [Abstract] Size of Facility Loans System restoration costs threshold for increase in permitted debt to EBITDA covenant ratio Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract] Long-term Debt, Fiscal Year Maturity [Abstract] 2016 2017 2018 2019 2020 Secured debt amount with asset liens Replacement fund requirements to be satisfied in 2016 Replacement Fund Requirements This element represents those amounts to be set aside for the repair and replacement of real or personal property in the foreseen future. Such amount may be satisfied by certification of property additions. Sinking fund requirements to be satisfied in 2016 Sinking Fund Requirements Amount to be paid in following year into the sinking fund. Such amount may be satisfied by certification of property additions. Condensed Balance Sheet Statement [Table] Condensed Balance Sheet Statement [Table] Condensed Balance Sheet Statements, Captions [Line Items] Condensed Balance Sheet Statements, Captions [Line Items] Cash and cash equivalents Notes receivable — subsidiaries Notes Receivable, Related Parties, Current Accounts receivable — subsidiaries Accounts Receivable, Related Parties, Current Other assets Other Assets, Current Other Assets: Assets, Noncurrent [Abstract] Investment in subsidiaries Investment In Subsidiary The amount of investment in a subsidiary, eliminated on consolidation. Other assets Notes payable — subsidiaries Notes Payable, Related Parties, Current Accounts payable: Accounts Payable [Abstract] Subsidiaries Accounts Payable, Related Parties, Current Other Accounts Payable, Other, Current Other Liabilities: Liabilities, Other than Long-term Debt, Noncurrent [Abstract] Deferred tax liabilities Long-Term Debt Shareholders' Equity: Stockholders' Equity Attributable to Parent [Abstract] Common stock Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital Retained earnings (accumulated deficit) Retained Earnings (Accumulated Deficit) Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Total shareholders’ equity Equity Method Investments and Joint Ventures [Abstract] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Equity Method Investments [Table Text Block] Equity Method Investments [Table Text Block] CenterPoint Energy [Member] CenterPoint Energy [Member] Another company which is controlled, directly or indirectly, by its parent. The usual condition for control is ownership of a majority (over 50%) of the outstanding voting stock. The power to control may also exist with a lesser percentage of ownership, for example, by contract, lease, agreement with other stockholders or by court decree. Benefit Obligation [Member] Benefit Obligation [Member] Represents the benefit obligation on the balance sheet. U.S. Equity [Member] U.S. Equity [Member] U.S. Equity [Member] International Developed Market Equity [Member] International Developed Market Equity [Member] International Developed Market Equity [Member] Emerging Market Equity [Member] Emerging Market Equity [Member] Emerging Market Equity [Member] Fixed Income [Member] Fixed Income [Member] Fixed Income [Member] Cash and Cash Equivalents [Member] Cash and Cash Equivalents [Member] Common Collective Trust Funds [Member] Common Collective Trust Funds Member Consists of common collective trust funds invested in equities and fixed income securities. Investment grade or above [Member] Corporate Debt Securities Investment Grade Or Above Member This category includes information about debt securities with an investment grade or higher rating issued by a corporate entity with a promise of repayment. International equities [Member] Non Us Equities Member This category includes information about ownership interests or the right to acquire ownership interests in corporations and other legal entities which ownership interest is represented by shares of common or preferred stock, convertible securities, stock rights, or stock warrants. This category includes information about equity securities issued by a foreign corporate entity. Foreign equity securities are issuances by corporations outside the reporting entity's country of domicile. Cash received as collateral from securities [Member] Cash Received As Collateral Member The fair value of cash collateral received against securities loaned to borrowers. U.S. treasuries [Member] US Treasury Securities [Member] Mortgage backed securities [Member] Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] Asset backed securities [Member] Asset-backed Securities, Securitized Loans and Receivables [Member] Municipal bonds [Member] US States and Political Subdivisions Debt Securities [Member] Mutual funds [Member] Equity Funds [Member] International government bonds [Member] Foreign Government Debt Securities [Member] Real estate [Member] Real Estate [Member] Fair value of plan assets measurement [Axis] Fair Value, Hierarchy [Axis] Fair value of plan assets measurement [Domain] Fair Value Hierarchy [Domain] Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Inputs, Level 3 [Member] Investment Type [Axis] Investment Type [Axis] Investments [Domain] Investments [Domain] International Equity [Member] International Equity [Member] International Equity [Member] Fixed Income Funds [Member] Fixed Income Funds [Member] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Pension Plan Qualified [Member] Pension Plan Qualified [Member] A form of retirement plan that meets requirements of the Internal Revenue Code and as a result, is eligible to receive certain tax benefits. Defined Benefit Plan, Target Plan Asset Allocations Range Minimum Defined Benefit Plan, Target Plan Asset Allocations Range Minimum Defined Benefit Plan, Target Plan Asset Allocations Range Maximum Defined Benefit Plan, Target Plan Asset Allocations Range Maximum Pension plan assets, fair value Obligation To Return Cash Received As Collateral From Securities Lending, Defined Benefit Plan, Fair Value, Obligation To Return Cash Received As Collateral From Securities Lending, Represents the fair value of an obligation to return cash received as collateral from securities lending. Defined Benefit Plan, Actual Plan Asset Allocations Defined Benefit Plan, Actual Plan Asset Allocations Total contributions to the plans during the period Estimated future contributions in the next fiscal year Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year Defined Benefit Plan, Estimated Future Benefit Payments [Abstract] Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract] Pension benefit payments 2016 Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months Pension benefit payments 2017 Defined Benefit Plan, Expected Future Benefit Payments, Year Two Pension benefit payments 2018 Defined Benefit Plan, Expected Future Benefit Payments, Year Three Pension benefit payments 2019 Defined Benefit Plan, Expected Future Benefit Payments, Year Four Pension benefit payments 2020 Defined Benefit Plan, Expected Future Benefit Payments, Year Five Pension benefit payments 2021 - 2025 Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter Medicare subsidy receipts - 2016 Prescription Drug Subsidy Receipts, Next Twelve Months Medicare subsidy receipts - 2017 Prescription Drug Subsidy Receipts, Year Two Medicare subsidy receipts - 2018 Prescription Drug Subsidy Receipts, Year Three Medicare subsidy receipts - 2019 Prescription Drug Subsidy Receipts, Year Four Medicare subsidy receipts - 2020 Prescription Drug Subsidy Receipts, Year Five Medicare subsidy receipts - 2021 - 2025 Prescription Drug Subsidy Receipts, after Year Five Savings Plan [Abstract] Savings Plan Abstract Maximum percentage of eligible compensation employees may contribute to the savings plan (in hundredths) Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent Defined Contribution Plan, Employer Matching Contribution, Percent of Match Defined Contribution Plan, Employer Matching Contribution, Percent of Match Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay Defined Contribution Plan, Maximum Limit Of Account Balance In Company Stock, Percentage Defined Contribution Plan, Maximum Limit Of Account Balance In Company Stock, Percentage Represents the maximum percentage allowed of total account balance invested in company stock. Number of Common stock held by the savings plan (in shares) Number Of Shares In Common Stock Held By Savings Plan The number of shares of the entity's common stock held by the savings plan Percentage of investment in common stocks (in hundredths) Percentage Of Investment In Company Common Stock Percentage of investments held by the Savings Plan in the Entity's common stock. Defined Contribution Plan, Cost Recognized Defined Contribution Plan, Cost Recognized Postemployment Benefits [Abstract] Postemployment Benefits [Abstract] Postemployment Benefits, Period Expense Postemployment Benefits, Period Expense Postemployment benefit obligations Postemployment Benefits Liability, Noncurrent Other Non-Qualified Plans [Abstract] Other Nonqualified Plan Abstract Benefit expense related to deferred compensation plans Deferred Compensation Arrangement with Individual, Compensation Expense Other non-qualified plans benefit obligations deferred compensation Deferred Compensation Liability, Classified, Noncurrent Benefit obligations related to split-dollar life insurance arrangements Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent Split Dollar Life Insurance This represents the noncurrent liability related to split-dollar life insurance arrangements within other non-qualified plans. Earnings Per Share [Abstract] Award Type [Axis] Employee Stock Option [Member] Employee Stock Option [Member] Restricted Stock [Member] Restricted Stock [Member] Weighted Average Number of Shares Outstanding, Basic Plus: Incremental shares from assumed conversions: Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract] Stock options (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Diluted weighted average shares (in shares) Weighted Average Number of Shares Outstanding, Diluted Basic earnings per share: Earnings Per Share, Basic [Abstract] Basic earnings (loss) per share Earnings Per Share, Basic Diluted earnings per share: Earnings Per Share, Diluted [Abstract] Diluted earnings (loss) per share Earnings Per Share, Diluted Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Earnings Per Share Earnings Per Share [Text Block] Quarterly Financial Information [Text Block] Quarterly Financial Information [Text Block] Subsequent Events Subsequent Events [Text Block] Schedule of Regulatory Assets and Liabilities Schedule of Regulatory Assets and Liabilities [Table Text Block] Schedule of Regulatory Assets and Liabilities [Table Text Block] Sales [Member] Derivative Instrument [Axis] Derivative Contract [Domain] Weather Hedge Swaps [Member] Weather Hedge Swaps [Member] Heating-degree day swaps to mitigate the effect of fluctuations from normal weather for the winter heating season. Weather Hedge Term [Axis] Weather Hedge Term [Axis] Represents the term of the weather hedges Weather Hedge Term [Domain] Weather Hedge Term [Domain] [Domain] for Represents the term of the weather hedges 2013To2014 [Member] 2013To2014 [Member] Represents the range between years 2013 to 2014. 2014To2015 [Member] 2014To2015 [Member] Represents the range between the year 2014 to 2015. 2015To2016 [Member] 2015To2016 [Member] 2015To2016 [Member] Natural Gas Distribution [Member] Electric Transmission & Distribution [Member] Electric Transmission & Distribution [Member] Segment information for the Electric Transmission & Distribution segment which engages in the electric transmission and distribution business in the Texas Gulf Coast area. Weather Hedges [Abstract] Weather Hedges [Abstract] Weather Hedges [Abstract] Weather Hedges Term Weather Hedges Term Period of time used as the basis for weather hedges entered into by the company. Derivative, Gain (Loss) on Derivative, Net Derivative, Gain (Loss) on Derivative, Net Equity Stockholders' Equity Note Disclosure [Text Block] Indexed Debt Securities Text Block Indexed Debt Securities [Text Block] This item represents the entire disclosure related to Indexed Debt Securities (ZENS) and Time Warner Securities. Variable Interest Entity, Primary Beneficiary [Member] Variable Interest Entity, Primary Beneficiary [Member] Allowance for Doubtful Accounts Receivable, Current Allowance for Doubtful Accounts Receivable, Current Securities Related to ZENS Trading Securities [Table] Subordinated Debt ZENS Member Securities Related to ZENS Major Types of Debt and Equity Securities [Axis] Subsidiary of CenterPoint Energy equity holdings [Domain] Major Types of Debt and Equity Securities [Domain] TW Common [Member] TW Common Member Common stock of Time Warner. TWC Common [Member] TWC Common Member Common stock of Time Warner Cable. AOL Common [Member] AOL Common Member Common stock of AOL. Time Common [Member] Time Common [Member] Time Common [Member] TW Securities [Member] TW Securities [Member] Represents collectively TW Common, TWC Common, AOL Common and Time Common securities related to ZENS. Debt Component Of ZENS [Member] Debt Component Of ZENS [Member] Represents the bifurcated fixed rate debt component of the ZENS obligation Derivative Component Of ZENS [Member] Derivative Component Of ZENS [Member] Represents the bifurcated derivative component of the ZENS obligation Schedule of Trading Securities [Line Items] Schedule of Trading Securities and Other Trading Assets [Line Items] Number of shares of common stock held by subsidiary of CenterPoint Energy (in shares) Investment Owned, Balance, Shares Zero Premium Exchangeable Subordinated Notes [Abstract] Zero Premium Exchangeable Subordinated Notes Abstract Original principal amount of Zero Premium Exchangeable Subordinated Notes issued by CenterPoint Energy in September 1999 Debt Instrument, Face Amount Long-term Debt, Gross Long-term Debt, Gross Percentage of market value of referenced shares of Time Warner Common each zero premium exchangeable subordinated note could be exchanged for cash (in hundredths) Subordinated Note Cash Exchangeable Percentage Of Fair Value The percentage of the fair value of the referenced TW Common shares attributable to each note and the percentage of composite fair value each note can be exchanged for cash. The referenced shares of common stock for each zero premium exchangeable subordinated note (in shares) Number Of Shares Referenced In Exchangeable Subordinated Note Number of shares attributable to each note and referenced in determining the fair value of the cash to be exchange at behest of note holder. Business Acquisition, Share Price Business Acquisition, Share Price Proceeds from Sale and Maturity of Trading Securities Held-for-investment Proceeds from Sale and Maturity of Trading Securities Held-for-investment Reduction In ZENS Debt Reduction In ZENS Debt Represents the amount of reduction in ZENS debt related to the partial settlement of ZENS Referenced common shares Referenced common shares [Abstract] Referenced common shares [Abstract] Contingent principal amount of indexed debt securities issued by CenterpPoint Energy in September 1999 and outstanding and exchangeable Debt Instrument Contingent Principal Amount Outstanding Amount of outstanding contingent principal under the zero premium exchangeable subordinated notes contract contingent principal clause. Target annual yield from interest and cash dividends on referenced shares before principal amount of indexed debt securities is increased or decreased (in hundredths) Target Annual Yield On Referenced Shares Before Increase Or Decrease Of Principal Amount Of Subordinated Note The target annual yield from interest and cash dividends on referenced shares, before any adjustment to increase or decrease principal amount of subordinated note is made. The cash exchange amount from referenced shares per $1,000 face amount of individual notes Subordinated Note Cash Exchange Amount Per Each $1,000 Of Original Note The amount of cash each $1,000 original principal amount of ZENS can be exchanged for a the behest of the note holder. Face amount of each indexed debt security notes issued by CenterPoint Energy in September 1999 Dollar Face Amount Of Individual Note The dollar denomination for each individual note The accretion rate for interest charges on bifurcated debt component of indexed debt securities (in hundredths) Bifurcated Debt Annual Accretion Rate The accretion rate for interest charges on bifurcated debt component of indexed debt securities (in hundredths) TW Securities Tw Securities [ Abstract] TW Securities Proceeds from Sale and Maturity of Marketable Securities Proceeds from Sale and Maturity of Marketable Securities Gain (loss) on TW Securities Marketable Securities, Gain (Loss) TW Securities Debt component of ZENS Debt Component Of Zens Abstract Debt Component of ZENS Accretion of debt component of ZENS Accretion Of Debt Component Indexed Debt Securities The amount of annual balance buildup of the debt portion of indexed debt securities up to the contingent principal amount on debt component of ZENS. 2 % interest paid Interest Paid Debt Component Indexed Debt Securities The amount of stated interest paid during the current period for interest owed on debt component of ZENS. Redemption of Indexed Debt Securities Redemption Of Current Indexed Debt Securities Represents the amount of indexed debt securities redeemed in the period. Realized Loss On Indexed Debt Securities Realized Loss On Indexed Debt Securities Represents the amount of realized loss on indexed debt securities recognized in the period. Debt Component of ZENS Derivative component of ZENS Derivative Component Of Zens Abstract Derivative Component of ZENS Redemption of Derivative Indexed Debt Securities Redemption Of Derivative Indexed Debt Securities Represents the amount of derivative indexed debt securities redeemed in the period. Reduction In ZENS Derivative Obligation Reduction In ZENS Derivative Obligation Represents the amount of reduction in ZENS derivative obligation due to the partial settlement Distribution to ZENS holders Loss (gain) on indexed debt securities Gain on Indexed Debt Securities Gain on Indexed Debt Securities Represents the gain on indexed debt securities recognized during the period, excluding loss related to distribution to ZENS holders. Derivative Component of ZENS Indebtedness to CERC Corp. [Member] Indebtedness to CERC Corp. [Member] Represents the indebtedness to CERC Corp. Variable Interest Entities [Axis] Variable Interest Entities [Axis] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] Nature of Expense [Axis] Nature of Expense [Axis] Interim Period, Costs Not Allocable [Domain] Interim Period, Costs Not Allocable [Domain] Natural Gas Expenses [Member] Natural Gas Expenses [Member] Represents natural gas expenses, including transportation and storage costs. Subordinated Units [Member] Subordinated Units [Member] Subordinated Units [Member] Transitional Service [Member] Transitional Service [Member] Transitional services costs, including the costs of seconded employees. Southeast Supply Header LLC [Member] Southeast Supply Header LLC [Member] Represents ownership of a 1.0 Bcf per day, 274-mile interstate pipeline that runs from the Perryville Hub in Louisiana to Coden, Alabama. OGE [Member] OGE [Member] OGE [Member] ArcLight [Member] ArcLight [Member] ArcLight [Member] Notes receivable - affiliated companies Due from Affiliate, Noncurrent Interest Income, Related Party Interest Income, Related Party Due from Related Parties, Current Due from Related Parties, Current Service Agreement Notice For Termination At Term End Service Agreement Notice For Termination At Term End Represents the number of days notice required prior to termination of services agreement. Partners' Capital Account, Units, Sold in Public Offering Partners' Capital Account, Units, Sold in Public Offering Share Price Share Price Proceeds from Issuance Initial Public Offering Proceeds from Issuance Initial Public Offering Equity Method Investment, Contributed Ownership Percentage Equity Method Investment, Contributed Ownership Percentage Equity Method Investment, Contributed Ownership Percentage Reimbursement Revenue Reimbursement Revenue Accounts Receivable, Related Parties Accounts Receivable, Related Parties Affiliate Costs Affiliate Costs Accounts payable - subsidiaries Equity Method Investment, Ownership, Shares Equity Method Investment, Ownership, Shares Equity Method Investment, Ownership, Shares Management Rights Ownership Percentage Management Rights Ownership Percentage Represents the percentage of management rights in the general partner of Enable Incentive Distribution Right, Percentage Incentive Distribution Right, Percentage Entity's interest in incentive distribution rights held by the general partner. Equity in earnings (losses) of unconsolidated affiliates Income (Loss) from Equity Method Investments Impairment Charges Impairment Charges This represents the total impairment charges reported during the period, including the impairment of equity method investment and entity's share of impairment of goodwill and long-lived assets recorded by equity method investment. Impairment of CenterPoint Energy’s equity method investment in Enable Equity Method Investment, Other than Temporary Impairment Goodwill And Long-LIved Assets Impairment Charges, Entity's Share Goodwill And Long-LIved Assets Impairment Charges, Entity's Share This represents entity's share of impairment charges recorded during the period by equity method investment for goodwill and long-lIved assets. Goodwill by Reportable Segments Schedule of Goodwill [Table Text Block] Summary of Accounting Policies [Table] Summary of Accounting Policies [Table] Summary of Accounting Policies [Table] Other Income [Member] Other Income [Member] Inventory [Axis] Inventory [Axis] Inventory [Domain] Inventory [Domain] Materials And Supplies [Member] Materials And Supplies [Member] Represents balance in inventory at period end of materials and supplies. Public Utilities, Inventory, Natural Gas [Member] Public Utilities, Inventory, Natural Gas [Member] Prepaid Expenses and Other Current Assets [Member] Prepaid Expenses and Other Current Assets [Member] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Significant Accounting Policies [Line Items] Significant Accounting Policies [Line Items] Significant Accounting Policies [Line Items] Equity Method Investment, Ownership Percentage Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage Incentive Distribution, Distribution Per Unit Incentive Distribution, Distribution Per Unit Incentive Distribution Right, Maximum Incentive Distribution Right, Maximum Maximum additional incentive right to the general partner with quarterly distribution per unit exceeding $0.330625 Amount of removal costs recognized as a component of depreciation expense recorded as a regulatory liability Capitalized Interest Costs, Including Allowance for Funds Used During Construction Capitalized Interest Costs, Including Allowance for Funds Used During Construction Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity Provision for doubtful accounts Provision for Doubtful Accounts Inventory Write-down Inventory Write-down Restricted cash accounts Restricted Cash and Cash Equivalents Schedule of Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Weighted Average [Member] Weighted Average [Member] Other property [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Property, Plant and Equipment, Net, by Type [Abstract] Total Property, Plant and Equipment, Gross Total accumulated depreciation and amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Property, plant and equipment, net Weighted Average Useful Lives Property, Plant and Equipment, Useful Life Depreciation and Amortization [Abstract] Depreciation, Depletion and Amortization [Abstract] Depreciation expense Depreciation Amortization expense Amortization Total depreciation and amortization expense Depreciation, Depletion and Amortization Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] Beginning balance Asset Retirement Obligation Accretion expense Asset Retirement Obligation, Accretion Expense Revisions in estimates of cash flows Asset Retirement Obligation, Revision of Estimate Ending balance Background Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] Principles of Consolidation Consolidation, Policy [Policy Text Block] Revenues Revenue Recognition, Policy [Policy Text Block] Long-lived Assets Impairment or Disposal of Long-Lived Assets, Including Intangible Assets, Policy [Policy Text Block] Regulatory Assets and Liabilities Public Utilities, Policy [Policy Text Block] Depreciation and Amortization Expense Depreciation, Depletion, and Amortization [Policy Text Block] Capitalization of Interest and Allowance for Funds Used During Construction Allowance for Funds Used During Construction, Policy [Policy Text Block] Income Tax Income Tax, Policy [Policy Text Block] Accounts Receivable and Allowance for Doubtful Accounts Trade and Other Accounts Receivable, Policy [Policy Text Block] Inventory Inventory, Policy [Policy Text Block] Derivative Instruments Derivatives, Policy [Policy Text Block] Investments in Other Debt and Equity Securities Marketable Securities, Policy [Policy Text Block] Environmental Costs Environmental Costs, Policy [Policy Text Block] Statement of Consolidated Cash Flows Cash and Cash Equivalents, Policy [Policy Text Block] New Accounting Pronouncements, Policy New Accounting Pronouncements, Policy [Policy Text Block] Derivative Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Other Significant Noncash Transaction [Axis] Other Significant Noncash Transaction [Axis] Other Significant Noncash Transaction, Name [Domain] Other Significant Noncash Transaction, Name [Domain] Statement of Cash Flows [Abstract] Adjustments to reconcile net income (loss) to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Amortization of deferred financing costs Deferred income taxes Unrealized loss (gain) on marketable securities Marketable Securities, Unrealized Gain (Loss), Excluding Other than Temporary Impairments Loss (gain) on indexed debt securities Indexed Debt Securities, Gain (Loss) This item represents the net total realized and unrealized gain (loss) included in earnings for the period related to indexed debt securities. Write-down of natural gas inventory Equity in (earnings) losses of unconsolidated affiliates, net of distributions Income (Loss) from Equity Method Investments, Net of Dividends or Distributions Pension contributions Pension Contributions Changes in other assets and liabilities: Accounts receivable and unbilled revenues, net Increase (Decrease) in Accounts and Other Receivables Inventory Increase (Decrease) in Inventories Taxes receivable Increase (Decrease) in Income Taxes Receivable Fuel cost recovery Increase (Decrease) in over (under) Energy Recovery Non-trading derivatives, net Increase (Decrease) in Derivative Assets and Liabilities Margin deposits, net Increase (Decrease) in Margin Deposits Outstanding Interest and taxes accrued Increase Decrease Interest and taxes accrued Increase (decrease) in interest and taxes accrued. Net regulatory assets and liabilities Increase (Decrease) in Regulatory Assets and Liabilities Other current assets Other assets Increase (Decrease) in Other Noncurrent Assets Other liabilities Increase (Decrease) in Other Noncurrent Liabilities Other, net Net cash provided by operating activities Cash Flows from Investing Activities: Capital expenditures Payments to Acquire Productive Assets Distributions from unconsolidated affiliates in excess of cumulative earnings Proceeds from Equity Method Investment, Dividends or Distributions, Return of Capital Decrease (increase) in restricted cash of transition and system restoration bond companies Increase (Decrease) in Restricted Cash Investment in unconsolidated affiliates Payments to Acquire Equity Method Investments Cash contribution to Enable Cash Contributed Cash Contributed Proceeds from sale of marketable securities Other, net Payments for (Proceeds from) Other Investing Activities Net cash used in investing activities Cash Flows from Financing Activities: Increase (decrease) in short-term borrowings, net Proceeds from (Repayments of) Short-term Debt Proceeds from long-term debt Proceeds from Issuance of Long-term Debt Long-term revolving credit facility Proceeds from Long-term Lines of Credit Cash paid for debt exchange and debt retirement Payments of Debt Extinguishment Costs Payment of common stock dividends Other, net Net cash provided by (used in) financing activities Net Increase (Decrease) in Cash and Cash Equivalents Supplemental Disclosure of Cash Flow Information: Supplemental Cash Flow Information [Abstract] Cash Payments: Cash Payments [Abstract] Interest, net of capitalized interest Interest Paid, Net Income taxes (refunds), net Income Taxes Paid, Net Non-cash transactions: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Accounts payable related to capital expenditures Capital Expenditures Incurred but Not yet Paid Formation of Enable Contribution of Property Exercise of SESH put to Enable Transfer from Investments Goodwill Goodwill and Intangible Assets Disclosure [Text Block] Reportable Business Segments Segment Reporting Disclosure [Text Block] Equity Method Investment, Summarized Financial Information, Gross Profit (Loss) [Abstract] Equity Method Investment, Summarized Financial Information, Gross Profit (Loss) [Abstract] Operating revenues Equity Method Investment, Summarized Financial Information, Revenue Cost of sales, excluding depreciation and amortization Equity Method Investment, Summarized Financial Information, Cost of Sales Impairment of goodwill and other long-lived assets Equity Method Investment, Summarized Financial Information, Impairment of Goodwill and Long-Lived Assets The amount of impairment of goodwill and long-lived assets reported by an equity method investment of the entity. Operating income (loss) Equity Method Investment, Summarized Financial Information, Operating Income (Loss) The amount of operating income (loss) reported by an equity method investment of the entity. Net income (loss) attributable to Enable Equity Method Investment, Summarized Financial Information, Net Income (Loss) CenterPoint Energy’s interest Equity Method Investment, Gross Equity In Earnings (Losses) This represents the gross equity in earnings (losses) of equity method investment, excluding any basis difference. Basis difference amortization (1) Basis Difference Accretion Gain Basis Difference Accretion Gain Impairment of CenterPoint Energy’s equity method investment in Enable CenterPoint Energy’s equity in earnings (losses), net (2) Income Loss From Equity Method Investments, Net Of Basis Difference This represents the total income (loss) from equity method investments for the period, net of basis difference. Income (Loss) From Equity Method Investment, Excluding Impairment Charge Income (Loss) From Equity Method Investment, Excluding Impairment Charge This item represents the entity's proportionate share for the period of the net income (loss), excluding the impairment of goodwill and long-lived assets, of its investee to which the equity method of accounting is applied. Equity Method Investment, Summarized Financial Information, Assets [Abstract] Equity Method Investment, Summarized Financial Information, Assets [Abstract] Current assets Equity Method Investment, Summarized Financial Information, Current Assets Non-current assets Equity Method Investment, Summarized Financial Information, Noncurrent Assets Current liabilities Equity Method Investment, Summarized Financial Information, Current Liabilities Non-current liabilities Equity Method Investment, Summarized Financial Information, Noncurrent Liabilities Non-controlling interest Equity Method Investment, Summarized Financial Information, Noncontrolling Interest Enable partners’ capital Equity Method Investment Summarized Financial Information, Equity Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract] Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract] CenterPoint Energy’s ownership interest in Enable partners’ capital Equity Method Investment, Underlying Equity in Net Assets CenterPoint Energy’s basis difference Equity Method Investment, Basis Difference This represents the basis difference of an equity method investment. Proceeds from Equity Method Investment, Dividends or Distributions Basis Difference, Amortization Period Basis Difference, Amortization Period Represents the basis difference amortization period in years Schedule of Segment Reporting [Table] Schedule of Segment Reporting Information, by Segment [Table] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Operating Segments [Member] Operating Segments [Member] Intersegment Eliminations [Member] Intersegment Eliminations [Member] Interstate Pipelines [Member] Interstate Pipelines [Member] Segment information for the Interstate Pipelines segment which includes the interstate natural gas pipeline operations. Field Services [Member] Field Services [Member] Segment information for the Field Services business segment which includes the natural gas gathering, treating and processing operations. Midstream Investments [Member] Midstream Investments [Member] Midstream Investments [Member] Major Customers [Axis] Customer [Axis] Name of Major Customer [Domain] Customer [Domain] Affiliates of NRG Energy, Inc. [Member] Affiliates of NRG Energy, Inc. [Member] Affiliates of NRG Energy, Inc. [Member] Affiliates of Energy Future Holdings Corp. [Member] Affiliates of Energy Future Holdings Corp. [Member] Affiliates of Energy Future Holdings Corp. [Member] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Revenues from External Customers and Intersegment Revenues Depreciation and Amortization Operating Income (Loss) Operating Income (Loss) Total Assets Expenditures for Long-Lived Assets Capital Expenditures for Long-Lived Assets Capital Expenditures for Long-Lived Assets Equity income Total regulatory assets Regulatory Assets Lease Commitments Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Basic and Diluted Earnings Per Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Equity Method Investments and Joint Ventures Disclosure [Text Block] Equity Method Investments and Joint Ventures Disclosure [Text Block] Schedule of Inventory Schedule of Utility Inventory [Table Text Block] Fair Value Assets And Liabilities Measured On Recurring Basis Disclosure Items Table Fair Value Assets And Liabilities Measured On Recurring Basis Disclosure Items [Table] -- None. No documentation exists for this element. -- Options Held [Member] Options Held [Member] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value, Measurements, Recurring [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Hierarchy [Axis] Fair Value, Measurements, Fair Value Hierarchy [Domain] Measurement Basis [Axis] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement [Member] Portion at Fair Value Measurement [Member] Fair value [Member] Estimate of Fair Value Measurement [Member] Carrying amount [Member] Reported Value Measurement [Member] Fair Value, assets and liabilities measured on recurring basis, financial statement captions Fair Value Assets And Liabilities Measured On Recurring Basis Financial Statement Captions [Line Items] Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Illiquid forward price low range Fair Value Inputs, Price Per MMBtu Fair value inputs used for valuing physical forward contracts using a discounted cash flow model, including illiquid forward price curve locations. Option volatilities low range Fair Value Assumptions, Expected Volatility Rate Fair Value, Assets, Level 1 to Level 2 Transfers, Amount Fair Value, Assets, Level 1 to Level 2 Transfers, Amount Fair Value, Assets, Level 2 to Level 1 Transfers, Amount Fair Value, Assets, Level 2 to Level 1 Transfers, Amount Fair Value, Liabilities, Level 1 to Level 2 Transfers, Amount Fair Value, Liabilities, Level 1 to Level 2 Transfers, Amount Fair Value, Liabilities, Level 2 to Level 1 Transfers, Amount Fair Value, Liabilities, Level 2 to Level 1 Transfers, Amount Corporate equities Fair Value Assets Measured On Recurring Basis Corporate Equities This element represents a certain statement of financial position asset caption which represents a class of assets, or which may include an individual asset, measured at fair value on a recurring basis. Investments, including money market funds Investments, Fair Value Disclosure Derivative Asset, Fair Value, Gross Liability Derivative Asset, Fair Value, Gross Liability Total assets Assets, Fair Value Disclosure, Recurring Liabilities Liabilities [Abstract] Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset Derivative Liability, Fair Value, Gross Asset Derivative Liability, Fair Value, Gross Asset Natural gas derivatives (2) Total liabilities Liabilities, Fair Value Disclosure, Recurring Cash collateral posted with counterparties Cash collateral posted with counterparties The amount of cash that is posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features. Fair value measurement using significant unobservable input (level 3) reconciliation [Roll Forward] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Beginning balance Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs Total gains Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings Total settlements Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Settlements Transfers out of Level 3 Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers out of Level 3 Transfers into Level 3 Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers into Level 3 Ending balance (1) The amount of total gains for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at the reporting date Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Notes receivable - affiliated companies Notes Receivable, Fair Value Disclosure Long-term debt Long-term Debt, Fair Value Short-term Borrowings and Long-term Debt Debt Disclosure [Text Block] Schedule of Revenue by Major Customers, by Reporting Segments [Table] Schedule of Revenue by Major Customers, by Reporting Segments [Table] Concentration Risk Benchmark [Axis] Customer [Axis] Subsegments [Axis] Subsegments [Axis] Subsegments [Domain] Subsegments [Domain] Subsegments Consolidation Items [Axis] Subsegments Consolidation Items [Axis] Subsegments Consolidation Items [Domain] Subsegments Consolidation Items [Domain] Revenue, Major Customer [Line Items] Revenue, Major Customer [Line Items] Financial Data for Business Segments Schedule of Segment Reporting Information, by Segment [Table Text Block] Revenues by Products and Services Revenue from External Customers by Products and Services [Table Text Block] Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block] Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block] Midstream Investments [Table Text Block] Midstream Investments [Table Text Block] Tabular presentation of equity earnings and equity investment related to Midstream Investments for the period [Table Text Block] Revenues Natural gas Cost of Natural Gas Purchases Operation and maintenance Utilities Operating Expense, Maintenance, Operations, and Other Costs and Expenses Taxes other than income taxes Taxes, Miscellaneous Total Costs and Expenses Operating Income Gain (Loss) on marketable securities Gain (Loss) on indexed debt securities Interest and other finance charges Interest on transition and system restoration bonds Interest on Transition and System Restoration Bonds Interest and debt related expenses associated with transition and system restoration bonds. Other, net Income (Loss) Before Income Taxes Income tax expense (benefit) Basic Earnings Per Share: Basic Earnings (Loss) Per Share Diluted Earnings Per Share: Diluted Earnings (Loss) Per Share Weighted Average Shares Outstanding, Basic Weighted Average Shares Outstanding, Diluted Selected Quarterly Financial Information [Abstract] Selected Quarterly Financial Information [Abstract] Operating income Impairment Charge, net of tax Impairment Charge, net of tax This represents the total impairment charges, net of tax, reported during the period, including the impairment of equity method investment and entity's share of impairment of goodwill and long-lived assets recorded by equity method investment.