Accounts receivable, net ($49 and $46 related to VIEs at December 31, 2010 and March 31, 2011, respectively) Accounts Receivable, Net, Current Amount accrued for remediation of Minnesota sites (in number of sites) Accumulated other comprehensive loss Total accumulated other comprehensive loss Less accumulated depreciation and amortization Additional paid-in capital Capital expenditures Payments to Acquire Productive Assets Net unrealized gain (loss) from derivative instruments Amortization of deferred financing costs Amortization of Financing Costs Basic Earnings Per Share Basic earnings per share (dollars per share) Cash and cash equivalents ($198 and $82 related to VIEs at December 31, 2010 and March 31, 2011, respectively) Cash and Cash Equivalents at Beginning of Period Cash and Cash Equivalents at End of Period Interest, net of capitalized interest Interest Paid, Net Non-trading derivatives, net Increase (Decrease) in Commodity Contract Assets and Liabilities Taxes receivable Increase (Decrease) in Income Taxes Receivable Inventory Increase (Decrease) in Inventories Fuel cost over recovery Increase (Decrease) in over (under) Energy Recovery Net regulatory assets and liabilities Increase (Decrease) in Regulatory Assets and Liabilities Changes in other assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Accounts payable Increase (Decrease) in Accounts Payable Commercial Paper [Member] Commitments and Contingencies [Text Block] Common stock shares authorized (in shares) Total common stock issued (in shares) Total common stock outstanding (in shares) Common stock (424,746,177 shares and 425,377,257 shares outstanding at December 31, 2010 and March 31, 2011, respectively) Comprehensive income Comprehensive Income [Text Block] Natural gas Cost of Purchased Oil and Gas Total current liabilities Liabilities, Current Current Liabilities: Liabilities, Current [Abstract] Current portion of other long-term debt Other Long-term Debt, Current Short-term Borrowings and Long-term Debt [Text Block] Amount of senior notes issued (CERC Corp. senior notes) Debt Instrument, Interest Rate, Stated Percentage (in hundredths) Debt Instrument, Name [Domain] Debt Instrument [Axis] Debt Instrument [Line Items] Schedule of Long-term Debt Instruments [Table] Debt issuance costs Payments of Debt Issuance Costs Deferred income taxes Deferred Income Tax Expense (Benefit) Defined Benefit Plans [Domain] Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Non-trading derivative assets Derivative Assets, Current Non-trading derivative assets Derivative Assets, Noncurrent Derivative Instruments [Text Block] Non-trading derivative liabilities Derivative Liabilities, Current Non-trading derivative liabilities Derivative Liabilities, Noncurrent Diluted Earnings Per Share Diluted earnings per share (dollars per share) Dividend Declared [Member] Equity in earnings of unconsolidated affiliates Income (Loss) from Equity Method Investments Effective tax rate (in hundredths) Electric Transmission and Distribution [Member] Extinguishment of debt, principal amount Income Taxes Income Tax Disclosure [Text Block] Income tax refunds, net Income Taxes Paid, Net Taxes receivable Income Taxes Receivable, Current Decrease in restricted cash of transition and system restoration bonds companies Increase (Decrease) in Restricted Cash Stock options (in shares) Goodwill Goodwill Interest accrued on unrecognized tax benefits Natural gas inventory Energy Related Inventory, Natural Gas in Storage Investment in unconsolidated affiliates Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Liabilities [Abstract] Liabilities [Abstract] Total Liabilities and Shareholders' Equity Liabilities and Stockholders' Equity LIABILITIES AND SHAREHOLDERS' EQUITY Liabilities and Stockholders' Equity [Abstract] Revolving credit facility borrowing rate Total credit facility amount Line of Credit [Member] Bank loans due 2012 [Member] 2015 2014 2012 2013 2011 Unconditional Purchase Obligation, Category of Goods or Services Acquired [Domain] Recorded Unconditional Purchase Obligation by Category of Item Purchased [Axis] Recorded Unconditional Purchase Obligation [Line Items] Recorded Unconditional Purchase Obligation [Table] Total long-term debt Long term debt Long-term Debt: Long-term Debt, Excluding Current Maturities [Abstract] After 2015 Recovery of compensatory damages sought by plaintiffs Investment in marketable securities Marketable Securities, Current Portion of unrecognized tax benefits that, if recognized, would reduce the effective income tax rate Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities Cash Flows from Financing Activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Cash Flows from Investing Activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Cash Flows from Operating Activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Net Income Net income Net income Net Income (Loss) Attributable to Parent Net Decrease in Cash and Cash Equivalents Cash and Cash Equivalents, Period Increase (Decrease) New Accounting Pronouncements [Text Block] Total Nonoperating Income (Expense) Other Income (Expense): Nonoperating Income (Expense) [Abstract] Interest and other finance charges Interest and Debt Expense Total other assets Assets, Noncurrent Other Assets: Other Assets: Total other liabilities Liabilities, Noncurrent Other Liabilities: Liabilities, Noncurrent [Abstract] Operating Income Operating Income Revenues Revenues from External Customers Background and Basis of Presentation [Text Block] Other, net Increase (Decrease) in Other Operating Assets and Liabilities, Net Adjustment related to pension and other postretirement plans (net of tax of $1 and $2) Other Comprehensive Income, Defined Benefit Plans Adjustment, Net of Tax Prepaid expenses and other current assets ($39 related to VIEs at both December 31, 2010 and March 31, 2011) Other Assets, Current Other, net Payments for (Proceeds from) Other Investing Activities Other, net Other, net Other Nonoperating Income (Expense) Other Postretirement Benefit Plans, Defined Benefit [Member] Payment of common stock dividends Payments of Dividends, Common Stock Employee Benefit Plans [Text Block] Pension Plans, Defined Benefit [Member] Amortization of net loss Defined Benefit Plan, Amortization of Gains (Losses) Amortization of prior service credit Amortization of transition obligation Total contributions to the plans during the period Estimated future contributions in the next fiscal year Expected return on plan assets Defined Benefit Plan, Expected Return on Plan Assets Interest cost Net periodic cost Defined Benefit Plan, Net Periodic Benefit Cost Service cost Defined Benefit Plans Disclosures, Defined Benefit Plans [Axis] Defined Benefit Plan Disclosure [Line Items] Schedule of Defined Benefit Plans Disclosures [Table] Cumulative preferred stock shares authorized (in shares) Cumulative preferred stock par value (in dollars per share) Proceeds from issuance of common stock, net Proceeds from commercial paper, net Proceeds from Issuance of Commercial Paper Proceeds from long-term debt Proceeds from Issuance of Long-term Debt Property, plant and equipment Property, plant and equipment, net Property, Plant and Equipment, Net Property, Plant and Equipment: Regulatory Matters [Text Block] Investment in unconsolidated affiliates Payments to Acquire Interest in Joint Venture Regulatory assets ($2,597 and $2,542 related to VIEs at December 31, 2010 and March 31, 2011, respectively) Regulatory Assets, Noncurrent Regulatory liabilities Regulatory Liability, Noncurrent Payments of long-term debt Repayments of Long-term Debt Amount of cash consideration provided related to CERC exchange offer Reporting Segment [Domain] Accumulated deficit Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Text Block] Goodwill [Text Block] Subsequent Events [Text Block] Reportable Business Segments [Text Block] Financial data for business segments Intersegment Revenues Segment Reporting Information, by Segment [Axis] Segment Reporting Information [Line Items] Schedule of Segment Reporting Information, by Segment [Table] Short-term Debt [Line Items] Schedule of Short-term Debt [Table] Short-term borrowings Total short term borrowings Capital Stock [Text Block] Subsequent Event, Date Subsequent Event Type [Axis] Subsequent Event [Line Items] Subsequent Event [Table] Subsequent Event Type [Domain] Supplemental Disclosure of Cash Flow Information: Supplemental Cash Flow Information [Abstract] Total current assets Assets, Current Current Assets: Current Assets: Unrecognized tax benefits Weighted Average Shares Outstanding, Diluted Weighted average shares assuming dilution (in shares) Weighted Average Shares Outstanding, Basic Weighted average shares outstanding (in shares) Weighted average shares outstanding (in shares) Total Assets Total Assets Unrealized gain on marketable securities Marketable Securities, Unrealized Gain (Loss) Other Other Liabilities, Current Other Other Liabilities, Noncurrent Dividends Declared Per Share Fair Value, by Balance Sheet Grouping [Table] Estimated fair value of financial instruments, debt instruments [Table] Fair Value, by Balance Sheet Grouping, Disclosure Item Amounts [Axis] Fair Value, Disclosure Item Amounts [Domain] Carrying Amount [Member] Fair Value [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Long-term Debt [Abstract] Equity in earnings of unconsolidated affiliates, net of distributions Income (Loss) from Equity Method Investments, Net of Dividends or Distributions Assets [Abstract] Fair Value Measurements Fair Value, Measurement Inputs, Disclosure [Text Block] Fair value, assets measured on a recurring basis Fair Value, Assets Measured on Recurring Basis [Table] Fair Value, Assets Measured on Recurring Basis, Disclosure Items [Axis] Fair Value, Assets Measured on Recurring Basis, Disclosure Items [Domain] Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items] Investments, including money market funds Natural gas derivatives, assets Fair value, liabilities measured on a recurring basis Natural gas derivatives, liabilities Assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 3 [Member] Estimated fair value of financial instruments, debt instruments Net deferred loss from cash flow hedges Adjustment related to pension and postretirement plans Accumulated Other Comprehensive Income (Loss), Defined Benefit Pension and Other Postretirement Plans, Net of Tax Other Other Long-term Debt, Noncurrent Other Other Assets, Noncurrent Expenses: Operating Expenses [Abstract] Total Operating Expenses Basic earnings per share calculation: Earnings Per Share, Basic [Abstract] Diluted earnings per share calculation: Diluted earnings per share: Outstanding shares with the options to purchase not included in the computation of diluted earnings per share (in shares) Earnings Per Share [Abstract] Earnings Per Share [Abstract] Earnings Per Share [Abstract] Amount collected from insurance companies to be used for future environmental remediation Income Before Income Taxes Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Cumulative Effects of Changes in Accounting Principles, Noncontrolling Interest Parent Company [Member] CenterPoint Energy [Member] Product Financing Arrangement [Member] Common stock shares par value (in dollars per share) Treasury stock (in shares) Tax effects on adjustment to pension and other postretirement plans Total shareholders' equity Stockholders' Equity Attributable to Parent Income tax expense Amount of adjustment to regulatory assets due to actuarially determined net present value of lost future health care deductions Gain on marketable securities Marketable Securities, Gain (Loss) Accounts payable related to capital expenditures Capital Expenditures Incurred but Not yet Paid Unamortized debt issuance cost Common stock, shares outstanding Plus: Incremental shares from assumed conversions: Earnings Per Share [Text Block] Taxes other than income taxes Taxes, Miscellaneous Net after-tax extraordinary loss Total non-trading derivative assets and liabilities net of collateral Shareholders' Equity: Stockholders' Equity: Commitments and Contingencies (Note 12) Commitments and Contingencies Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Long-term Debt, Type [Axis] Accounts payable Interest accrued Interest Payable, Current Taxes accrued Taxes Payable, Current Other comprehensive income: Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Total Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Long-term Debt, Type [Domain] Benefit obligations Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent Derivatives, Fair Value, by Balance Sheet Location [Axis] Balance Sheet Location [Domain] Other Assets [Member] Other Liabilities [Member] Derivatives, Fair Value [Line Items] Derivative assets fair value Derivative liabilities fair value Derivative gross volumes (Bcf) Natural Gas Contracts [Member] Indexed Debt Securities Derivative [Member] Derivatives, Fair Value, by Derivative Instrument Risk [Axis] Gains (losses) in Other Income (Expense) [Member] Gains (Losses) in Revenue [Member] Gains (Losses) in Expense: Natural Gas [Member] Income Statement and Other Comprehensive Income Location [Domain] Total fair value of the derivative instruments that contain credit risk contingent features that are in a net liability position The aggregate fair value of assets already posted as collateral Credit Risk Contingent Features assets Income Statement Impact of Derivative Activity Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) by Income Statement Location [Axis] Derivative Instruments, Gain (Loss) by Derivative Instrument Risk [Axis] Derivative Instruments, Gain (Loss) by Hedging Relationship, by Income Statement Location, by Derivative Instrument Risk [Table] Derivative Contract Type [Domain] Fair Value of Derivative Instruments Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Amendment Flag Current Fiscal Year End Date Document Period End Date Entity [Text Block] Entity [Domain] Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Current Reporting Status Entity Filer Category Entity Public Float Entity Registrant Name Entity Central Index Key Entity Common Stock, Shares Outstanding Document Fiscal Year Focus Document Fiscal Period Focus Legal Entity [Axis] Document Type Rate of estimated recovery by CenterPoint Houston Rate of estimated recovery seek by CenterPoint Houston until securitized. Derivative Instruments [Abstract] Derivative Instruments - (Tables) [Abstract] Derivative Instruments - (Details) [Abstract] Sales Revenue From Natural Gas Derivatives Unrealized Gains Revenue derived from natural gas derivatives unrealized gains. Increased (decreased) natural gas revenues from the unrealized net gains (losses) of derivative instruments Expense From Natural Gas Derivatives Unrealized Losses Expense derived from natural gas derivatives unrealized losses. Increased (decreased) natural gas expense from the unrealized net (gains) losses of derivative instruments Weather Hedges Term Period of time used as the basis for weather hedges entered into by the company. Term of normal weather used as the basis for weather hedges (in years) Weather Hedges Gain Loss Recognized The amount of gain or loss recognized from weather hedges. Losses recognized from weather hedges Derivative Gross Volume Long Position Net long position volume amount taken by the company in its natural gas derivative contracts. Net long position (Bcf) Derivative Gross Volume Basis Swaps Long Position The amount of net long position constituted by basis swaps. Amount of net long position constituted by basis swaps Derivative Gross Volume Segment Long Position The amount of net long position comprised of price stabilization activities of the Natural Gas Distribution business segment. Amount of net long position comprised of price stabilization activities of the Natural Gas Distribution business segment Collateral Netting Amount of collateral netted with derivative contracts. Collateral netting Derivative Instruments Price Stabilization Cost Derivative activity in expenses includes costs associated with price stabilization activities of the Natural Gas Distribution business segment. Costs associated with price stabilization activities of the Natural Gas Distribution business segment included in Expenses Fair Value Measurements [Abstract] Fair Value Measurements - (Details) [Abstract] Fair Value Measurements - (Tables) [Abstract] 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. Corporate equities Fair Value Assets Measured On Recurring Basis Assets Total This element represents a certain statement of financial position asset caption which represents all assets, measured at fair value on a recurring basis. Total assets Fair Value Liabilities Measured On Recurring Basis Liabilities Total This element represents a certain statement of financial position liability caption which represents all liabilities, measured at fair value on a recurring basis. Total liabilities 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 Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation Roll Forward A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. Fair value measurement using significant unobservable input (level 3) reconciliation [Roll Forward] Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Net Asset Liability Value This element represents the net asset/liability measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances. Beginning balance Ending balance Total Unrealized Gains Or Losses Net Abstract Total unrealized gains or losses [Abstract] Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Unrealized Gain Loss Included In Earnings This element represents total unrealized gains or losses for the period, arising from assets measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in earnings or resulted in a change in net asset value. Included in earnings Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Unrealized Gain Loss Included In Regulatory Assets This element represents total unrealized gains or losses for the period, arising from assets measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in regulatory assets. Included in regulatory assets Purchases Sales And Other Settlements Net [Abstract] Total settlements, gross [Abstract] Included In Regulatory Assets Purchases Sales And Other Settlements Net This element represents purchases, sales, issuances, and settlements (net), included in regulatory assets, which have taken place during the period in relation to assets measured at fair value on a recurring basis using unobservable inputs (Level 3). Included in regulatory assets Amount Of Total Gains For Period Included In Earnings This item represents the amount of the total change in unrealized (holding) gains or losses for the period which are included in the statement of income (or changes in net assets) in assets still held at reporting period. Such unrealized (holding) gains or losses relate to those assets still held at the reporting date for which fair value is measured on a recurring basis using significant unobservable inputs (Level 3). Amount of total gains for the period included in earnings Long Term Debt Fair Value Disclosure This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents long term debt as of the balance sheet date Long-term debt Goodwill [Abstract] Goodwill - (Tables) [Abstract] Goodwill By Reportable Business Segment Text Block The carrying amount of goodwill, by reportable segment. Goodwill by reportable segment Comprehensive Income [Abstract] Components of total comprehensive income (net of tax) [Text Block] Schedule of comprehensive income (loss), including the pre-tax amounts, tax (expense) benefits, and after-tax amounts for each component of comprehensive income. Components of total comprehensive income (net of tax) Components of accumulated other comprehensive loss [Text Block] Schedule of accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, including foreign currency translation items, certain pension adjustments, and unrealized gains and losses on certain investments in debt and equity securities as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge. Components of accumulated other comprehensive loss Capital Stock [Abstract] Capital Stock Shares Authorized The maximum number of capital shares permitted to be issued by an entity's charter and bylaws. Capital stock shares authorized (in shares) Short-term Borrowings and Long-term Debt [Abstract] Receivables Facility Range Minimum Reflects the minimum availability under the receivables facility Receivables facility range, minimum Receivables Facility Range Maximum Reflects the maximum availability under the receivables facility Receivables facility range, maximum Receivables Facility Advance Capacity Reflects the available capacity under the receivables facility at the balance sheet date. Receivable facility maximum advance capacity Letters Of Credit Outstanding Amount of letters of credit outstanding Amount of outstanding letters of credit Debt Covenant Debt To Ebitda Total debt to earnings before interest, taxes, depreciation and amortization permitted ratio under covenant. Debt to EBITDA covenant ratio, before amendment Debt Covenant Debt To Ebitda Amended Total debt to earnings before interest, taxes, depreciation and amortization temporary permitted ratio under covenant. Debt to EBITDA covenant ratio, amendment 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 System restoration costs threshold for increase in permitted debt to EBITDA covenant ratio Percentage on limitation of debt to total capitalization under covenant (in hundredths) Percentage on limitation of debt to total capitalization under covenant. Income Taxes [Abstract] Amount of non-cash recorded to income tax expense as result of change in tax law The increase in total income tax expense for the period as result of change in tax law. Summary of unrecognized tax benefits [Text Block] Summary of unrecognized tax benefits including (1) portion of unrecognized tax benefits that, if recognized, would reduce the effective income tax rate, and (2) interest accrued on unrecognized tax benefits. Summary of unrecognized tax benefits Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Estimated Range of Change, Minimum For a tax position taken for which it is reasonably possible that the total amount of unrecognized tax benefit will significantly increase or decrease within twelve months of the balance sheet date, provide an estimate of the range of the reasonably possible change. This is the minimum anticipated amount. Range of change possible in unrecognized tax benefits over the next 12 months, minimum Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Estimated Range of Change, Maximum For a tax position taken for which it is reasonably possible that the total amount of unrecognized tax benefit will significantly increase or decrease within twelve months of the balance sheet date, provide an estimate of the range of the reasonably possible change. This is the maximum anticipated amount. Range of change possible in unrecognized tax benefits over the next 12 months, maximum Commitments and Contingencies [Abstract] Natural Gas Plant Capacity The total volume, in million cubic feet, of natural gas that can flow through a gathering and treating facility per day. Expanded natural gas capacity per day (in million cubic feet) Amount Spent On Original Project Scope For Gathering System Expansion Amount spent to date on original project scope for expansion, including the purchase of the original facilities. Amount spent on original project scope for expansion Years lapsed under volume commitment (in number of years) Number of years lapsed under volume commitment, in order to permit the system to gather and treat natural gas, under existing long-term agreements as of balance sheet date. Years of volume commitment (in number of years) Number of years under volume commitment, in order to permit the system to gather and treat natural gas, under existing long-term agreements as of balance sheet date. Additional Natural Gas Plant Capacity Per Expansion Election The additional volume, in million cubic feet, of natural gas that can flow through a gathering and treating facility per day due to the expansion election. Additional natural gas capacity per day under the expansion election (in million cubic feet) Total Capacity Of System After Expansion The total volume, in million cubic feet, of natural gas that can flow through a gathering facility and treating per day due to the expansion. Total capacity per day of system after expansion (in million cubic feet) Estimated Total Capital Expenditures For Expansion The estimated total capital expenditures for the expansion election. Total costs of additional expansion Potential Additional Natural Gas Plant Capacity Under Potential Additional Expansion Election Potential additional natural gas capacity per day under potential additional expansion election (in million cubic feet) Potential additional natural gas capacity per day under potential additional expansion election (in million cubic feet) Total Capacity Of System After Potential Additional Expansion Total capacity per day of system after potential additional expansion (in billion cubic feet) Total capacity per day of system after potential additional expansion (in billion cubic feet) Estimated Total Capital Expenditures For Potential Additonal Expansion Total costs of potential additional expansion Total costs of potential additional expansion Estimated Remaining Amount To Complete Original Scope Of Gathering System Estimated remaining costs to complete expansion. Estimated remaining costs to complete expansion LegalEnvironmentalAndOtherRegulatoryMattersLegalMattersGasMarketManipulationCasesAbstract Legal Environmental And Other Regulatory Matters Legal Matters Gas Market Manipulation Cases Abstract Loss Contingency Total Gas Market Manipulation Cases The total amount of gas market manipulation lawsuits filed against a company. Approximate number of gas market manipulation lawsuits naming CenterPoint and/or Reliant Energy (in number of lawsuits) Loss Contingency Pending Gas Market Manipulation Lawsuits Number The total number of pending lawsuits related to gas market manipulation. Number of gas market manipulation lawsuits pending for CenterPoint and its affiliates (in number of lawsuits) Loss Contingency Pending Natural Gas Measurement Lawsuits Number The total number of pending lawsuits related to natural gas measurement. Number of gas market mismeasurement lawsuits pending for CenterPoint and its affiliates (in number of lawsuits) Loss Contingency Kansas Gas Measurement Lawsuit Defendants The number of gas measurement lawsuit defendants named with the company in a pair of Kansas lawsuits. Approximate number of pipeline companies named in the mismeasurement lawsuits (in number of companies) Loss Contingency Pending Measurement Lawsuit Number of gas measurement lawsuits requesting class certification and has been amended four times. Number of gas measurement lawsuits seeking class certification and has four amendments (in number of cases) Loss Contingency Lawsuit Amendments The number of times a lawsuit has been amended. Number of times gas measurement lawsuit was amended (in number of amendments) Loss Contingency Term Of Allegations Number of years during which the defendant is alleged to have mismeasured natural gas. Number of years the plaintiffs claim the defendants have engaged in the systematic mismeasurement of natural gas (in years) Loss Contingency Defendants Dismissed Number of defendants dismissed from the claims of the plaintiffs. Number of CenterPoint subsidiaries dismissed from the claims of the plaintiff (in number of claims) Site Contingency Remaining Minnesota Sites Number of other sites in the company's Minnesota service territory. Number of remaining sites in the Minnesota service territory (in number of sites) Site Contingency Sites Without Liability Number of sites in Minnesota where the company believes it has no liability. Number of the remaining sites in the Minnesota service territory where the company believes it has no liability (in number of sites) Site Contingency Loss Exposure Low Estimate Low-end of the range estimate of the reasonably possible loss exposure at an individual site. Minimum estimated remediation costs for the Minnesota sites Site Contingency Loss Exposure High Estimate High-end of the range estimate of the reasonably possible loss exposure at an individual site. Maximum estimated remediation costs for the Minnesota sites Site Contingency Estimated Time Frame To Resolve Contingency Low Estimate Low-end of the range estimated time frame for remediation to continue. Minimum years of remediation for the Minnesota sites (in years) Site Contingency Estimated Time Frame To Resolve Contingency High Estimate High-end of the range estimated time frame for remediation to continue. Maximum years of remediation for the Minnesota sites (in years) Site Contingency Remediation Costs Included In Rates Annual amount received from customers used to fund normal on-going remediation costs. Annual amount included in rates to fund normal on-going remediation costs Guarantee Obligations Demand Charges Present Value The present value of demand charges included in transportation contracts. Approximate amount of undiscounted demand charges under the transportation contracts Guarantee Obligations Collateral Posted Approximate amount of collateral posted as security on transportation contracts Approximate amount of collateral posted as security on transportation contracts Site Contingency Completed Remediation Number of manufactured gas plant sites where remediation is complete, other than ongoing operations. Number of sites where remediation is complete, other than ongoing operations (in number of sites) Incremental Common Shares Attributable To Restricted Stock Restricted shares whose issuance is contingent upon certain conditions and shall be considered outstanding and included in the computation of diluted Earnings Per Share. Restricted stock (in shares) Schedule Of Earnings Per Share Basic And Diluted By Common Class Text Block This element may be used to capture the complete disclosure pertaining to an entity's basic and diluted earnings per share. Basic and diluted earnings per share Reportable Business Segments [Abstract] Reportable Business Segments - (Details) [Abstract] Segment Reporting Pension Plan Assets This represents the assets recognized in the Other Operations segment that are associated with the defined benefit plans. Pension and other postemployment related regulatory assets included in total assets of Other Operations Subsequent Events [Abstract] Subsequent Events - (Details) [Abstract] Subsequent Event, Dividends Declared Aggregate dividends declared, after the balance sheet date, but before the issuance of the financial statements, for each share of common stock outstanding. Subsequent Event, Amount Condensed Consolidated Balance Sheets (Unaudited) [Abstract] Condensed Statements of Cash Flows (Unaudited) [Abstract] Amount of estimated increase in revenues from a settlement on gas operations request The amount of estimated increase in revenues from a settlement on a gas operations rate increase request reached with the Railroad Commission and 66 cities. Amount of settlement on gas operations request Requested increase in annual base revenues from gas operations annual filings with Oklahoma and parts of Texas Requested increase in annual base revenues from gas operations annual filings with Oklahoma and certain portions of Texas. Condensed Statements of Consolidated Income (Unaudited) [Abstract] Sales to subsidiaries of Customer 1 Sales to subsidiaries of NRG Retail LLC, the successor to RRI's Texas retail business. Sales to subsidiaries of NRG Retail LLC Sales to subsidiaries of Customer 2 Sales to subsidiaries of TXU Energy Retail Company LLC. Sales to subsidiaries of TXU Energy Retail Company LLC Amount of reduction to deferred tax assets due to actuarially determined net present value of lost future health care deductions The tax effect as of the balance sheet date of the amount of the estimated future tax deductions arising from actuarially determined net present value of lost future health care deductions, which can only be deducted for tax purposes when actual costs are incurred, and which can only be realized if sufficient tax-basis income is generated in future periods to enable the deduction to be taken. Line of Credit Facility Utilization Fee Reflects the fee charge for borrowings exceeding 50% of credit facility at anytime. Utilization fee on borrowings exceeding fifty percent of total credit facility (in hundredths) Percentage of Utilization of Credit facility Percentage of utilization of credit facility before an additional utilization fee will be applied to borrowings. Percentage of utilization of credit facility Amount of Pension and Postemployment Benefits Deferred as Regulatory Asset Amount of pension and postemployment benefits deferred as regulatory assets. Amount of pension and postemployment benefits deferred as a regulatory asset Number of days for Texas Supreme Court on rehearing the case from filing a motion The number of days from filing a motion for the Texas Supreme Court to rule on the motion to rehear the case. Number of days for Texas Supreme Court on rehearing the case from filing a motion (in number of days) Derivative gains and (losses) in the Statements of Consolidated Income Realized and unrealized gains (losses) recognized on derivatives during the period. Total amount of application seeking approval of recovery of various costs The total amount of the application filed in April 2011 with the Texas Utility Commission seeking approval of the recovery of various costs. Portion of application seeking recovery of energy efficiency program costs The portion of the application filed in April 2011 with the Texas Utility commission seeking recovery of 2012 estimated energy efficiency program costs. Portion of application seeking an energy efficiency performance bonus based on 2010 program achievements The portion of the application filed in April 2011 with the Texas Utility commission seeking an energy efficiency performance bonus based on 2010 program achievements. Portion of application seeking recovery of lost revenues due to verified and reported 2010 energy savings The portion of the application filed in April 2011 with the Texas Utility commission seeking recovery of lost revenues due to verified and reported 2010 energy savings. Portion of application seeking for under-recovery of 2010 program costs The portion of the application filed in April 2011 with the Texas Utility commission seeking recovery for the under-recovery of 2010 program costs. Recorded Unconditional Purchase Obligation [Abstract] Recorded Unconditional Purchase Obligation Schedule of Capital Expansion Projects [Abstract] Schedule of Capital Expansion Projects Current Assets [Member] Line item in the statement of financial position in which the fair value amounts of the derivative instruments are included. Current Liabilities [Member] Line item in the statement of financial position in which the fair value amounts of the derivative instruments are included. Netting Adjustments [Member] This item represents the amount of adjustment to assets or liabilities, due to the netting arrangements as specified in master contract. Relates to derivative contracts with counterparties. Derivative Financial Instruments, Assets and Liabilities, Net [Member] This element represents types of derivative financial instruments (assets and liabilities) which are financial instruments or other contractual arrangements. Fair Value, Assets or Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Assets or Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, by Asset Type [Axis] This element represents a number of concepts which are required or determined to be provided for purposes of reconciling beginning and ending balances of fair value measurements of assets or liabilities using significant unobservable inputs (Level 3). . Fair Value, Assets or Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Asset Types [Domain] This element provides general categories of investment for which the fair value measurement of assets or liabilities using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes during the period. Fair Value, Assets or Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [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. 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. Interstate Pipelines [Member] Segment information for the Interstate Pipelines segment which includes the interstate natural gas pipeline operations. Competitive Natural Gas Sales and Services [Member] Segment information for the Competitive Natural Gas Sales and Services segment which represents the non-rate regulated gas sales and services operations, which consist of three operational functions: wholesale, retail and intrastate pipelines. Field Services [Member] Segment information for the Field Services business segment which includes the natural gas gathering, treating and processing operations. Other Operations [Member] Segment information for the Other Operations segment which consists primarily of other corporate operations which support all of the business operations. Goodwill Schedule [Table] Goodwill Reporting Information [Axis] Disclosure of goodwill for each reportable segment. Reporting Segments [Domain] A component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements. Goodwill Schedule [Line Items] Senior notes issued, due 2021 (CERC Corp. senior notes) [Member] Senior notes, due 2021, issued for extinguishment of another existing senior notes. Senior notes are notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Senior note holders are paid off in full before any payments are made to junior note holders. Senior notes issued, due 2041 (CERC Corp. senior notes) [Member] Senior notes, due 2041, issued for extinguishment of another existing senior notes. Senior notes are notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Senior note holders are paid off in full before any payments are made to junior note holders. Senior notes issued, due 2021 (CERC exchange offer) [Member] Senior notes, due 2021, issued to replace another existing senior notes. Senior notes are notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Senior note holders are paid off in full before any payments are made to junior note holders. Exchanged senior debt, due 2013 [Member] Senior notes, due 2013, replaced by a newly issued senior notes. Senior notes are notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Senior note holders are paid off in full before any payments are made to junior note holders. Senior notes issued, due 2011 (CERC Corp. senior notes) [Member] Senior notes, due 2011. Senior notes are notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Senior note holders are paid off in full before any payments are made to junior note holders. 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. 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. Senior notes 2013 to 2037 [Member] Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Senior note holders are paid off in full before any payments are made to junior note holders. CERC Corp. receivables facility [Member] An arrangement that in form is a sale with full right of return but in substance is a financing in that the financier is not the end customer, is not at risk other than credit risk similar to any other form of lending arrangement, and typically is repaid from collections of sales made to actual customers including an amount that constitutes interest. Natural Gas supply commitments [Member] Details minimum payment obligations for natural gas supply commitments. Magnolia Gathering System [Member] Information on the Magnolia Gathering System which is the result of an agreement between CenterPoint Energy Field Services, Inc., an indirect wholly-owned subsidiary of Encana Corporation, and a wholly-owned subsidiary of Royal Dutch Shell plc. The agreement is to provide gathering and treating services for natural gas production from certain Haynesville Shale and Bossier Shale formations in Louisiana. Olympia Gathering System [Member] Additional long term agreement between CenterPoint Energy Field Services, Inc., a wholly-owned subsidiary of Encana Corporation, and an indirect wholly-owned subsidiary of Dutch Shell plc to provide gathering and treating services for their natural gas production from certain Haynesville and Bossier Shale formations in Texas and Louisiana. Schedule of Capital Expansion Projects [Table] Schedule of Capital Expansion Projects, by Project [Axis] A table of capital expansion projects by project. Capital Expansion Project [Domain] The capital expansion projects by name. Schedule of Capital Expansion Projects [Line Items] Reconciling Eliminations [Member] Eliminating entries used in business segment consolidation. 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 mainentnance and repairs. Gain (loss) on Indexed Debt Securities Gain (loss) on Indexed Debt Securities. Loss on indexed debt securities Interest on Transition and System Restoration Bonds Interest on Transition and System Restoration Bonds. Interest on transition and system restoration bonds Accrued unbilled revenues Estimated cycle billing accrued revenue. Materials and supplies Materials and supplies. 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. Current portion of VIE transition and system restoration bonds long-term debt Indexed Debt Current Current portion of indexed debt Indexed debt securities derivative Indexed debt securities derivative Indexed debt securities derivative Accumulated Deferred Income Taxes Net Current The net accumulated deferred income taxes due estimated to reverse within one year or operating cycle if longer than a year. Accumulated deferred income taxes, net Accumulated Deferred Income Taxes Net Noncurrent The net accumulated deferred income taxes due estimated to reverse in more than one year or operating cycle if longer than a year. Accumulated deferred income taxes, net Transition And System Restoration Bonds Long Term Debt Non Current VIE transition and system restoration bonds Unrealized Loss Gain on Indexed Debt Securities Unrealized Loss Gain on Indexed Debt Securities. Unrealized loss on indexed debt securities Accounts receivable and unbilled revenues, net Accounts receivable and unbilled revenues, net. Margin deposits, net Margin deposits, net. Margin deposits, net Interest and taxes accrued Interest and taxes accrued. Interest and taxes accrued Net Change Other Current Assets Net Change Other Current Assets. Other current assets Net Change Other Current Liabilities Net Change Other Current Liabilities. Other current liabilities Net Change Other Assets Noncurrent Net Change Other Assets Noncurrent. Other assets Net Change Other Liabilities Noncurrent Net Change Other Liabilities Noncurrent. Other liabilities Cash received from DOE grant Cash received from DOE grant. Cash received from U.S Department of Energy grant Increase in Short Term Borrowings Net Increase in Short Term Borrowings Net. Decrease in short-term borrowings, net Cash Payments [Abstract] Cash Payments: Non Cash Transactions [Abstract] Non-cash transactions: Cash And Cash Equivalents, Variable Interest Entities Cash And Cash Equivalents, Variable Interest Entities. Cash and cash equivalents, VIE Accounts Receivable Net, Variable Interest Entities Accounts Receivable Net, Variable Interest Entities. Accounts receivable, net, VIE Prepaid Expenses And Other Current Assets Variable Interest Entities Prepaid Expenses And Other Current Assets Variable Interest Entities. Prepaid expenses and other current assets, VIE Regulatory Assets Variable Interest Entities Regulatory Assets Variable Interest Entities. Regulatory assets, VIE Cash paid for debt exchange The cash outflow for exchanged debt. Cash paid for debt exchange Background and Basis of Presentation [Abstract] New Accounting Pronouncements [Abstract] Employee Benefit Plans [Abstract] Employee Benefit Plans - (Details) [Abstract] Employee Benefit Plans - (Tables) [Abstract] Regulatory Matters [Abstract] Amount of approved base rate increase per year Amount of approved base rate increase per year for delivery charges related to June 2010 rate filing. Amount of approved decrease on charges to wholesale transmission customers Amount of approved decrease on charges to wholesale transmission customers related to June 2010 rate filing. Approved rate of return on equity The approved rate of return on equity related to 2010 filing. Approved rate of return on equity (in hundredths) Approved cost of debt The approved cost of debt related to June 2010 rate filing. Approved cost of debt (in hundredths) Approved percentage of capital structure based on long-term debt The percentage of the capital structure based on long-term debt related to June 2010 rate filing. Approved percentage of capital structure based on long-term debt (in hundredths) Approved percentage of capital structure based on equity The percentage of the capital structure based on equity related to June 2010 rate filing. Approved percentage of capital structure based on equity (in hundredths) Approved percentage of overall rate of return Approved percentage of overall rate of return related to June 2010 rate filing. Approved percentage of overall rate of return (in hundredths) Estimated reduction in annual operating income The estimated reduction in annual operating income as a result of the Texas Utility Commission's decision. Approved reduction in duration of residential AMS surcharge related to the reconciliation plan Approved reduction in the duration of the residential advanced metering system surcharge related to the reconciliation plan. Approved reduction in duration of residential AMS surcharge related to the reconciliation plan (in years) Number of cities in South Texas service territory Number of cities in South Texas service territory. Number of cities in South Texas service territory (in number of cities) Approximate number of customers in South Texas service territory Approximate number of customers in South Texas service territory. Approximate number of customers in South Texas service territory (in number of customers) Requested increase in base revenues from gas operations in South Texas service territory Requested increase in base revenues from gas operations in South Texas service territory. Initial Amount Of True Up Application The amount of the true-up application filed with the Texas Utility Commission, excluding interest, as allowed under Texas electric restructuring law. Initial amount of true-up application Amount Awarded In Final True Up Order This element represents the final amount of the Texas Utility Commission's final order, which included interest through August 31, 2004. Amount awarded in final true-up order by the Texas Utility Commission Amount Of Depreciation Expenses Denied By Regulatory Agency Amount of depreciation expenses denied by Texas Utility Commission and reversed by the Texas Supreme Court. Amount of depreciation expenses denied by Texas Utility Commission and reversed by the Texas Supreme Court Amount Regulatory Agency Reduced Stranded Cost Recovery Request For Present Value Of Certain Deferred Tax Benefits Associated With Former Electric Generation Assets Amount Texas Utility Commission reduced the stranded cost recovery request for the present value of certain deferred tax benefits associated with former electric generation assets Amount Texas Utility Commission reduced the stranded cost recovery request for the present value of certain deferred tax benefits associated with former electric generation assets Amount Of Transition Bonds Issued To Recover Additional True Up Costs Amount of transition bonds issued in Dec 2005 to recover additional true-up costs as allowed by the Texas electric restructuring law Amount of transition bonds issued to recover additional true-up costs as allowed by the Texas electric restructuring law Minimum Interest Rate On Transition Bonds Minimum interest rate on transition bonds issued in Dec 2005 Minimum interest rate on transition bonds (in hundredths) Maximum Interest Rate On Transition Bonds Maximum interest rate on transition bonds issued in Dec 2005 Maximum interest rate on transition bonds (in hundredths) Amount Of True Up Costs Recovered Through Issuance Of Transition Bonds The amount of true-up costs recovered through the issuance of the transition bonds in Dec 2005. Amount of true-up costs recovered through the issuance of the transition bonds Amount Of Competition Transition Charge Allowed By Regulatory Agency Amount of competition transition charge allowed by the Texas Utility Commission. Amount of competition transition charge allowed by the Texas Utility Commission Length Of Time Over Which Competition Transition Charge Is Collected Length of time over which the competition transition charge is collected Length of time over which the competition transition charge is collected (in years) Annual Interest Rate Of Competition Transition Charge Annual interest rate on competition transition charge Annual interest rate on competition transition charge (in hundredths) Amount Of Rate Case Expenses Allowed To Be Collected Under Separate Tariff Rider Amount of rate case expenses allowed to be collected over 3 years under separate tariff rider Amount of rate case expenses allowed to be collected under separate tariff rider Number Of Years To Collect Rate Case Expenses Number of years the Company can collect rate case expenses through separate tariff rider Number of years the Company can collect rate case expenses (in years) Total Amount Collectable Under Competition Transition Charge And Separate Tariff Rider Total amount collectable under competition transition charge and separate tariff rider Total amount collectable under competition transition charge and separate tariff rider Reduced Interest Rate On Competition Transition Charge Reduced interest rate on unrecovered balance of competition transition charge Reduced interest rate on competition transition charge (in hundredths) Transition Bonds2 Issued To Recover Balance Of Competition Transition Charge Transition bonds issued in Feb 2008 to recover costs covered with the competition transition charge order. Transition bonds Number Of Tranches Of Transition Bonds2 The number of tranches used for the issuance of the transition bonds issued in Feb 2008 to recover costs covered with the competition transition charge order. Transition bonds tranches (in number of tranches) Interest Rate On Transition Bonds 2 In Tranche 1 The interest rate on the transition bonds, tranche 1, issued in Feb 2008 to recover costs covered with the competition transition charge order. Interest rate on transition bonds in Tranche 1 (in hundredths) Interest Rate On Transition Bonds 2 In Tranche 2 The interest rate on the transition bonds, tranche 2, issued in Feb 2008 to recover costs covered with the competition transition charge order. Interest rate on transition bonds in Tranche 2 (in hundredths) Unrecognized Amount Of Allowed Equity Return Amount of allowed equity return on the true-up balance that has not been recognized as it will be recognized as it is recovered in rates. Amount of allowed equity return on the true-up balance that has not been recognized Amount Of Allowed Equity Return Recognized In Period Amount of allowed equity return on the true-up balance that was recognized in the period Amount of allowed equity return on the true-up balance that was recognized in the period Amount of increase in retail base rate for delivery charges supported by cost data and other information The amount of increase in retail base rate for delivery charges that is supported by cost data and other information. Amount Of Requested Retail Base Rate Increase For Delivery Charges Amount of requested retail base rate increase for delivery charges in June 2010 application. Amount of requested retail base rate increase for delivery charges Amount Of Requested Rate Increase For Wholesale Transmission Customers Amount of requested increase to wholesale transmission customers in June 2010 application. Amount of requested increase to wholesale transmission customers Amount Of Stimulus Grant Applied To Costs To Complete Advanced Metering System Amount of funds from the Department of Energy stimulus grant applied to the costs to complete the advanced metering system Amount of funds from the Department of Energy stimulus grant applied to the costs to complete the advanced metering system Total Amount Of Stimulus Grant Received Total amount of funds from the Department of Energy stimulus grant Total amount of funds from the Department of Energy stimulus grant Requested Reduction In Term Of Surcharge Related To Reconciliation Plan Requested reduction in the duration of the residential advanced metering system surcharge related to the reconciliation plan (in years) Requested reduction in the duration of the residential AMS surcharge related to the reconciliation plan (in years) Original Term Of Surcharge Original term of the residential advanced metering system surcharge related to the reconciliation plan (in years) Original term of the residential AMS surcharge (in years) Rate Of Return On Equity Sought The rate of return on equity sought by the company in June 2010 rate filing (in hundredths) The rate of return on equity sought by the company (in hundredths) Percentage Of Capital Structure Based On Equity The percentage of the capital structure based on equity (in hundredths) The percentage of the capital structure based on equity (in hundredths) Percentage Of Capital Structure Based On Long Term Debt The percentage of the capital structure based on long-term debt (in hundredths) The percentage of the capital structure based on long-term debt (in hundredths) Amount of partial performance bonus approved by the Texas Utility Commission related to 2010 energy efficiency program Amount of 2010 energy efficiency program parftial performance bonus approved by the Texas Utility Commission. Amount Of2010 Energy Efficiency Program Costs Submitted For Reimbursement Amount of 2010 energy efficiency program costs submitted for reimbursement through a surcharge Amount of 2010 energy efficiency program costs submitted for reimbursement Amount Of Bonus On2008 Energy Efficiency Program Costs Disallowed Amount of bonus on 2008 energy efficiency program costs disallowed Amount of bonus on 2008 energy efficiency program costs disallowed Amount Of2008 Energy Efficiency Program Costs Amount of 2008 energy efficiency program costs submitted for reimbursement Amount of 2008 energy efficiency program costs submitted for reimbursement Approximate Amount Of Costs Related To Energy Efficiency Programs Approximate amount of costs related to various energy efficiency programs requested for recovery in April 2010 Approximate amount of costs related to various energy efficiency programs Amount of partial performance bonus approved by the Texas Utility Commission related to 2011 energy efficiency program Amount of 2011energy efficiency program parftial performance bonus approved by the Texas Utility Commission. Portion Of Requested Amount Excluded From Recovery Which Relates To Performance Bonus Portion of requested amount excluded from recovery which relates to performance bonus for 2009 programs Portion of requested amount excluded from recovery which relates to performance bonus Portion Of Requested Amount Excluded From Recovery Which Relates To Lost Revenues Portion of requested amount excluded from recovery as relates to lost revenues associated with the 2009 program Portion of requested amount excluded from recovery as relates to lost revenues Number Of Cities In Gas Operation In Service Area1 Number of cities in Texas Coast service area (in number of cities) Number of cities in Texas Coast service area (in number of cities) Approximate Number Of Customers In Gas Operation In Service Area1 Approximate number of customers in cities and communities on the outskirts of Houston (in number of customers) Approximate number of customers in cities and communities on the outskirts of Houston (in number of customers) Amount Of Annual Revenue Increase Approved For Gas Operations In Service Area1 Increase in annual revenues from approved rate increases for gas operations in Texas Coast service area Increase in annual revenues from approved rate increases for gas operations in Texas Coast service area Number Of Cities Contesting New Rate For Gas Operations In Service Area1 Number of cities that contested the new rates in the Texas Coast service area (in number of cities) Number of cities that contested the new rates in the Texas Coast service area (in number of cities) Number Of Cities In Gas Operation In Service Area2 Number of cities in Houston service area (in number of cities) Number of cities in Houston service area (in number of cities) Approximate Number Of Customers In Gas Operation In Service Area2 Approximate number of customers in and around Houston (in number of customers) Approximate number of customers in and around Houston (in number of customers) Proposed Amount Of Annual Revenue Increase For Gas Operations In Service Area2 Proposed increase in annual revenues from gas operations in Houston service area Proposed increase in annual revenues from gas operations in Houston service area Amount Of Carrying Costs Of Gas Inventory Excluded From Rate Increase Amount of carrying costs of gas inventory excluded from rate increase Amount of carrying costs of gas inventory excluded from rate increase Amount Of Approved Annual Revenue Increase In Gas Operations In Service Area2 Amount of approved annual revenue increase in gas operations for the Houston area Amount of approved annual revenue increase in gas operations for the Houston area Approved Amount Of Surcharge In Gas Operations To Cover Storm Costs Approved amount of surcharge in gas operations to recover Hurricane Ike costs over three years Approved amount of surcharge in gas operations to recover Hurricane Ike costs Number Of Years For Surcharge To Recover Storm Costs Number of years for the surcharge to recover Hurricane Ike costs (in years) Number of years for the surcharge to recover Hurricane Ike costs (in years) Amount of expected reduction on stranded costs Amount of expected reduction on stranded costs. Amount of recovery related to capacity to auction true-up amounts Amount of recovery related to capacity to auction true-up amounts. Amount of recovery related to capacity auction true-up amounts Amount of interest component of excess mitigation credits did not address by Texas Supreme Court Amount of interest component of excess mitigation credits did not address by Texas Supreme Court. Requested increase in annual base revenues from gas operations annual billing determinant adjustment filing with Arkansas Public Service Commission Requested increase in annual base revenues from gas operations annual billing determinant adjustment filing with Arkansas Public Service Commission. Amount of estimated recovery by CenterPoint Houston based on Texas Supreme court's decision Amount of estimated recovery by CenterPoint Houston based on Texas Supreme court's decision related to remand to the Texas Utility Commission.