Supplemental Cash Flow Information [Abstract] Supplemental Cash Flow Information Cash Flow, Supplemental Disclosures [Text Block] Impact of Recently Issued Accounting Principles [Abstract] Impact of Recently Issued Accounting Principles Impact of Recently Issued Accounting Principles Disclosure Text Block Disclosure of changes in accounting principles, including adoption of new accounting pronouncements, that describes the new methods, amount and effects on financial statement line items. Earnings Per Share [Abstract] Numerator [Abstract] Numerator [Abstract] Numerator for Basic EPS Net Income (Loss) Available to Common Stockholders, Basic Add back earnings attributable to participating securities Dilutive Securities, Effect on Basic Earnings Per Share Net Income Net Income (Loss) Attributable to Parent Denominator [Abstract] Weighted average common shares outstanding (Denominator for Basic and Diluted EPS) (in shares) Weighted Average Number of Shares Outstanding, Basic Conversion of share based compensation arrnagements (in shares) Incremental Common Shares Attributable To Share Based Payment Arrangements Using Mixed Calculation Method Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method and contingent share methods. Weighted Average Number Diluted Shares Outstanding Adjustment (in shares) Weighted Average Number Diluted Shares Outstanding Adjustment Adjusted weighted average shares outstanding and assumed conversions outstanding (Diluted EPS) (in shares) Weighted Average Number of Shares Outstanding, Diluted Basic EPS (in dollars per share) Earnings Per Share, Basic Diluted EPS (in dollars per share) Earnings Per Share, Diluted Antidilutive securities excluded from computation of earnings per share, amount (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Antidilutive securities excluded from computation of earnings per share, option minimum exercise price (in dollars per share) Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit Antidilutive securities excluded from computation of earnings per share, option maximum exercise price (in dollars per share) Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit Segment Reporting [Abstract] Schedule of Segment Reporting Information, by Segment [Table Text Block] Earnings Per Share Earnings Per Share [Text Block] Fair Value Disclosures [Abstract] Fair Value, by Balance Sheet Grouping [Table Text Block] Environmental Matters Disclosure [Abstract] Site Contingency [Table] Environmental Remediation by Entity [Axis] Environmental Remediation by Entity Environmental Remediation by Entity [Domain] Environmental Remediation by Entity [Domain] Environmental Remediation by Entity Indiana Gas [Member] Refers to an entity under the control of the same parent as another entity (that is, a sister company). SIGECO [Member] Refers to an entity under the control of the same parent as another entity (that is, a sister company). Site Contingency [Line Items] Air Quality [Abstract] Environmental remediation [Abstract] Cost of most of the allowances granted to company for NOx and SO2 inventory usage Cost Of Most Of Allowances Granted To Company For Inventory Usage Of Nox And Co2 The cost to the company for most of the allowances granted under Clear Air Interstate Rule for usage of inventory of NOx and CO2. SIGECO investment in Property, Plant and Equipment, Pollution control equipment Public Utilities Property Plant And Equipment Pollution Control Equipment Period end amount of property, plant and equipment (PPE) related to pollution control equipment. Property, Plant and Equipment, amount of investment in pollution control equipment included in rate base Public Utilities Property Plant And Equipment Amount Of Investment In Pollution Control Equipment Included In Rate Base Discloses the amount of investment in pollution control equipment included in rate base. Percentage of coal fired generating fleet currently being scrubbed for SO2 (in hundredths) Percentage Of Coal Fired Generating Fleet Scrubbed For So2 Percent of coal fired generating fleet currently being scrubbed for SO2. Percentage of coal fired generating fleet currently controlled for NOx (in hundredths) Percentage Of Coal Fired Generating Fleet Controlled For N Ox Percent of coal fired generating fleet currently controlled for Nox. Percentage reduction of SO2 per Cross-State Air Pollution Rule (in hundredths) Percentage Reduction In So2 Per Cross State Air Polloution Rule Percentage reduction in SO2 per the Cross-State Air Pollution Rule. Percentage reduction of NOx per Cross-State Air Pollution Rule (in hundredths) Percentage Reduction In Nox Per Cross State Air Polloution Rule Percentage reduction in Nox per the Cross-State Air Pollution Rule. Allowances for NOx and SO2 granted The amount of allowances for NOx and SO2 that were granted at the balance sheet date. Clean Water Act [Abstract] Estimated capital expenditures related to Clean Water Act Estimated capital expenditures related to Clean Water Act granted that new infrastructure is required. Coal Ash Waste Disposal and Ash Ponds [Abstract] Ash Ponds And Coal Ash Disposal Regulations [Abstract] Estimated capital expenditures to comply with ash pond and coal ash disposal regulations Estimated capital expenditures to comply with ash pond and coal ash disposal regulations. Potential estimated capital expenditures to comply with ash pond and coal ash disposal regulations with stringent alternative Potential estimated capital expenditures to comply with ash pond and coal ash disposal regulations with most stringent alternative Potential estimated capital expenditures to comply with ash pond and coal ash disposal regulations with most stringent alternative. Estimated annual compliance costs maximum with ash pond and coal ash disposal regulation Estimated annual compliance costs maximum with ash pond and coal ash disposal regulation. Climate Changes [Abstract] Maximum level of greenhouse gas emissions that prompts requirement to obtain permit for facilities to construct new facility of significant modification to existing facility (in tons) Maximum Level Of Greenhouse Gas Emission To Prompt Need For Permit By Facilities The maximum level of greenhouse gas being emitted by facility that prompts the requirement for permit for new construction or significant modification of existing facility. Manufactured Gas Plants [Abstract] Environmental Remediation Efforts [Abstract] Site contingency, accrual, undiscounted amount SIGECO site contingency cumulative costs amount Estimated amount of cumulative costs to date for the environmental loss contingencies at all sites as of the balance sheet date. Remediation cost accrued and not yet spent a the end of the period Site Contingency Accrual Estimated undiscounted amount of the accrual for the environmental loss contingencies as of the balance sheet date. Number of sites identified with potential remedial responsibility for entity (in number of sites) Environmental Remediation Number Of Sites With Potential Remedial Responsibility Number of sites identified where the entity may potentially have some remedial responsibility Environmental cost recognized, recover from insurance carriers credited to expense Site Contingency Recovery From Insurance Carriers Of Environmental Remediation Cost Amount of the total estimated recovery from third party insurance carriers recorded to date that reduces environmental remediation expense. Number of sites identified with some remedial responsibility and has made arrangement along with other potentially responsible parties to cleanup (in number of sites) Environmental Remediation Number Of Sites With Remedial Responsibility With Arrangements In Place Number of sites identified where Indiana Gas has some remedial responsibility and has made arrangement with other potentially responsible parties to cleanup. Minimum percentage of responsibility for remediation cost for certain sites identified (in hundredths) Environmental Remediation Range Of Cost Responsibility To Cleanup Minimum Percentage Indiana Gas minimum percentage of responsibility for remediation cost to cleanup sites identified with other potentially responsible parties. Maximum percentage of responsibility for remediation cost for certain sites identified (in hundredths) Environmental Remediation Range Of Cost Responsibility To Cleanup Maximum Percentage Indiana Gas maximum percentage of responsibility for remediation cost to cleanup sites identified with other potentially responsible parties. Number of manufactured gas plant owned and operated with applications file to enroll in IDEM's VRP (in number of plants) Number Of Sites Owned Operated And Enrolled In Idem Vrp Number of sites owned, operated and enrolled in IDEM's VRP. Site contingency recovery from third party of environmental remediation cost Site Contingency, Recovery from Third Party of Environmental Remediation Cost Indiana Senate Bill 251 [Abstract] Power generation capacity for acquired landfill gas generations facility (in megawatts) Power Generating Capacity Of Acquired Landfill Gas Generation Facility Megawatts generating capacity for landfill gas generation facility purchased from a related entity with regulatory approval. Long term contract for purchase of electric power generated by wind energy (in megawatts) Long Term Contract For Purchase Electric Power Generated From Wind Energy Long-term contract to purchase stated megawatt of electric power generated by wind energy. Purchased electric power generated by wind energy (in megawatts) Purchase Electric Power Generated From Wind Energy Purchased stated megawatt of electric power generated by wind energy, excluding long-term contract to purchase stated megawatt of electric power generated by wind energy. Percentage of total electricity obtained by the supplier to meet the energy needs of its retail customers provided by clean energy sources (in hundredths) Percentage Of Total Electricity Obtained By Supplier To Meet Energy Needs Of Its Retail Customers Provided By Clean Energy Sources In Hundredths Percentage of total electricity obtained by the supplier to meet the energy needs of its retail customers provided by clean energy sources (in hundredths). Targeted goal percentage of total electricity obtained by the supplier to meet the energy needs of its retail customers provided by clean energy sources (in hundredths) Targeted goal percentage of total electricity obtained by the supplier to meet the energy needs of its retail customers provided by clean energy sources (in hundredths) Pipeline Safety Law [Abstract] Maximum fine for safety violations Maximum Fine For Safety Vioulations Under Pipeline Safety Act The maximum fine for safety violations under the Pipeline Safety, Regulatory Certainty and Job Creation Act of 2011. Jacobsville Superfund Site [Abstract] Superfund Site1 [Abstract] EPA identified sources of historic lead Epa Identified Sources Of Historic Lead Contamination A CERCLA soil contamination site in Evansville, Indiana which is inclusive of Vectren's Wagner Operations Center. Segment Reporting Segment Reporting Disclosure [Text Block] Statement of Financial Position [Abstract] Statement [Table] Statement [Table] Statement, Scenario [Axis] Statement, Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Statement [Line Items] Statement [Line Items] ASSETS Assets [Abstract] Current Assets [Abstract] Assets, Current [Abstract] Cash & cash equivalents Cash and Cash Equivalents, at Carrying Value Accounts receivable - less reserves of $6.2 & $6.7, respectively Accounts Receivable, Net, Current Accrued unbilled revenues Accrued unbilled revenues Unbilled amounts due for services rendered or products shipped. This element is distinct from unbilled contracts receivables because this is based on noncontract transactions. Inventories Inventory, Net Recoverable fuel & natural gas costs Deferred Fuel Cost Prepayments & other current assets Prepayments and other current assets Sum of the amounts paid in advance for capitalized costs that will be expensed with the passage of time or the occurrence of a triggering event, and will be charged against earnings within one year or the normal operating cycle, if longer and aggregate carrying amount, as of the balance sheet date, of current assets not separately presented elsewhere in the balance sheet . Total current assets Assets, Current Utility Plant [Abstract] Property, Plant and Equipment [Abstract] Original cost Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment Less: accumulated depreciation & amortization Public Utilities, Property, Plant and Equipment, Accumulated Depreciation Net utility plant Public Utilities, Property, Plant and Equipment, Net Investments in unconsolidated affiliates Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Other utility & corporate investments Other utility and corporate investments Other long-term utility and corporate investments not classified elsewhere in the taxonomy. Other nonutility investments Other nonutility investments Other long-term nonutility investments not classified elsewhere in the taxonomy. Nonutility plant - net Property, Plant and Equipment, Net Goodwill - net Goodwill Regulatory ssets Regulatory Assets, Noncurrent Other assets Other Assets, Noncurrent TOTAL ASSETS Assets LIABILITIES & SHAREHOLDERS' EQUITY Liabilities and Equity [Abstract] Current Liabilities [Abstract] Liabilities, Current [Abstract] Accounts payable Accounts Payable, Current Accounts payable to affiliated companies Accounts Payable, Related Parties, Current Refundable fuel & natural gas costs Refundable fuel and natural gas costs Electric and gas costs of a regulated entity that are refundable through future rate adjustments. Such costs are a form of regulatory liabilities and are expected to be refunded in less than 1 year through rate adjustments. Accrued liabilities Accrued Liabilities, Current Short-term borrowings Short-term Debt Current maturities of long-term debt Long-term Debt, Current Maturities Long-term debt subject to tender Long-term debt subject to tender Total of the portions of the carrying amounts as of the balance sheet date of long-term debt, which may include notes payable, bonds payable, debentures, mortgage loans, and commercial paper or such debt that is collateralized by a line of credit that has a remaining term less than one year, that contain an option, executable in one year or less, for the holder to put the debt back to the company. Total current liabilities Liabilities, Current Long-term Debt - Net of Current Maturities Long-term Debt - Net of Current Maturities And Debt Subject to Tender Sum of the carrying values as of the balance sheet date of all long-term debt, which is debt initially having maturities due after one year from the balance sheet date or beyond the operating cycle, if longer, but excluding the portions thereof scheduled to be repaid within one year (current maturities) or the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any. Also excludes the portion of debt that could be repaid in one year at the option of the holder. Deferred Income Taxes & Other Liabilities [Abstract] Liabilities, Noncurrent [Abstract] Deferred income taxes Deferred Tax Liabilities, Noncurrent Regulatory liabilities Regulatory Liability, Noncurrent Deferred credits & other liabilities Deferred Credits and Other Liabilities Total deferred credits and other liabilities Liabilities, Noncurrent Commitments & Contingencies (Notes 7, 9-12) Commitments and Contingencies Common Shareholders' Equity [Abstract] Stockholders' Equity Attributable to Parent [Abstract] Common stock (no par value) - issued & outstanding 82.1 & 81.9 shares, respectively Common Stock, Value, Issued Retained earnings Retained Earnings (Accumulated Deficit) Accumulated other comprehensive income (loss) Accumulated Other Comprehensive Income (Loss), Net of Tax Total common shareholders' equity Stockholders' Equity Attributable to Parent TOTAL LIABILITIES and SHAREHOLDERS' EQUITY Liabilities and Equity Document and Entity Information [Abstract] Entities [Table] Entities [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Entity Information [Line Items] Entity Information [Line Items] Entity Registrant Name Entity Central Index Key Current Fiscal Year End Date Entity Filer Category Document Type Document Period End Date Document Fiscal Year Focus Document Fiscal Period Focus Amendment Flag Entity Common Stock, Shares Outstanding ProLiance Holdings, LLC [Abstract] Summarized Financial Information Tabular disclosure of financial information of ProLiance Holdings, LLC. Income Statement [Abstract] OPERATING REVENUES [Abstract] Revenue, Net [Abstract] Gas utility Regulated Operating Revenue, Gas Electric utility Electric Domestic Regulated Revenue Nonutility Other Revenue, Net Total operating revenues Revenue, Net OPERATING EXPENSES [Abstract] Operating Expenses [Abstract] Cost of gas sold Cost of gas sold Cost of natural gas sold during the reporting period, operations of which is regulated by a federal or state agency. Cost of fuel & purchased power Cost of Domestic Regulated Electric Cost of nonutility revenues Other Cost of Operating Revenue Other operating Other Cost and Expense, Operating Depreciation & amortization Depreciation, Depletion and Amortization Taxes other than income taxes Taxes other than income taxes All taxes not related to income of the entity. Total operating expenses Operating Expenses OPERATING INCOME Operating Income (Loss) OTHER INCOME (EXPENSE) [Abstract] Nonoperating Income (Expense) [Abstract] Equity in (losses) of unconsolidated affiliates Income (Loss) from Equity Method Investments Other income - net Other Nonoperating Income (Expense) Total other income (expense) Nonoperating Income (Expense) Interest Expense INCOME BEFORE INCOME TAXES Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest INCOME TAXES Income Tax Expense (Benefit) Net Income AVERAGE COMMON SHARES OUTSTANDING DILUTED COMMOM SHARES OUTSTANDING EARNINGS PER SHARE OF COMMON STOCK: BASIC DILUTED DIVIDENDS DECLARED PER SHARE OF COMMON STOCK Common Stock, Dividends, Per Share, Declared Excise and Utility Receipts Taxes [Abstract] Excise and Utility Receipts Taxes Excise and Utility Receipts Taxes [Text Block] Description containing information regarding excise and utility receipts taxes as a single block of text. Legislative Matters Disclosure [Abstract] Legislative Matters Legislative Matters Disclosure [Text Block] Disclosures regarding legislative matters impacting the Company. less reserves of $6.2 & $6.7, respectively Allowance for Doubtful Accounts Receivable, Current Common Stock, No Par Value Common Stock, Shares, Issued Common Stock, Shares, Outstanding ProLiance Holdings, LLC Equity Method Investments Disclosure [Text Block] Debt Disclosure [Abstract] Financing Activities Debt Disclosure [Text Block] Accruals related to utility and nonutility plant purchases Public Utilities Accruals For Purchase Of Utility And Non Utility Plant Assets Pertains to the carrying amount of accruals for purchases of utility and nonutility plant assets as of balance sheet date. Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping, Disclosure Item Amounts [Axis] Fair Value, Disclosure Item Amounts [Domain] Carrying Amount [Member] Carrying (Reported) Amount, Fair Value Disclosure [Member] Estimated Fair Value [Member] Estimate of Fair Value, Fair Value Disclosure [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Long-term debt Long-term Debt, Fair Value Short-term Borrowings Short Term Borrowings 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 notes payable as of the balance sheet date. Cash and cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Short-term borrowings and notes payable Short Term Borrowings And Notes Payable 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. Fair value of Short-term borrowings and Notes payable at the balance sheet date. Money Market Funds, at Carrying Value Recovery period for call premiums on reacquisition of utility long-term debt (in years) Period over which call premium on reacquisition of long-term debt Period over which call premium on reacquisition of long-term debt are generally recovered. Carrying value of notes receivable, inclusive of any accrued interest and net of impairment reserves Notes Receivable, Fair Value Disclosure Error Corrections and Prior Period Adjustments, Description Number of groups (in number of groups) Number Of Segments Number of groups the company segregates its operation into. Portion of Indiana that is provided natural gas distribution and transportation services by the Gas Utility Services segment (in hundredths) Portion Of Indiana That Is Provided Natural Gas Distribution And Transportation Services By Gas Utility Services Segment The percentage of Indiana that is provided natural gas distribution and transportation services by the Gas Utility Services segment. Number of operating segments in the Nonutility Group Number of operating segments in the Nonutility Group The number of operating segments in the Nonutility group for which income is reviewed to make operating decisions. Number of reporting segments Number of reporting segments Number of segments for financial statement disclosures Schedule of Segment Reporting Information, by Segment [Table] Statement, Business Segments [Axis] Segment [Domain] Utility Group [Member] Nonutility Group [Member] Nonutility Group Corporate and Other Group [Member] Corporate and Other Group Corporate Elimination [Member] Products and Services [Axis] Products and Services [Domain] Gas Utility Services [Member] Electric Utility Services [Member] Other Operations [Member] Other Operations Group Eliminations [Member] Items resulting from intrasegment transactions (e.g., intrasegment profits). Infrastructure Services [Member] Infastructure Services [Member] Energy Services [Member] Coal Mining [Member] Energy Marketing [Member] Other Businesses [Member] Utility Group [Member] Segment Reporting Information [Line Items] Revenues Profitability Measure - Net income (loss) Excise and utility taxes collected and reported in operating revenue Excise Taxes Collected Organization and Nature of Operations [Abstract] Number of public utility subsidiaries owned by wholly owned subsidiary, Vectren Utility Holdings, Inc. (in number of subsidiaries) Number Of Public Utility Subsidiaries Owned By Wholly Owned Subsidiary Of Company Pertains to the number of public utility subsidiaries owned by wholly owned subsidiary, Vectren Utility Holdings, Inc. Estimated number of natural gas customers located in central and southern Indiana serviced by Indiana Gas Company, Inc. (in number of customers) Estimated Number Of Natural Gas Customers Serviced By Subsidiary 1 Pertains to the estimated number of natural gas customers located in central and southern Indiana serviced by Indiana Gas Company, Inc. Estimated number of electric customers located near Evansville in southwestern Indiana serviced by Southern Indiana Gas and Electric Company (in number of customers) Estimated Number Of Electric Customers Serviced By Subsidiary 2 Pertains to the estimated number of electric customers located near Evansville in southwestern Indiana serviced by Southern Indiana Gas and Electric Company. Estimated number of natural gas customers located near Evansville in southwestern Indiana serviced by Southern Indiana Gas and Electric Company (in number of customers) Estimated number of natural gas customers serviced by Subsidiary 2 Pertains to the estimated number of natural gas customers located near Evansville in southwestern Indiana serviced by Southern Indiana Gas and Electric Company. Estimated number of natural gas customers located near Dayton in west central Ohio serviced by the Ohio operations (in number of customers) Estimated Number Of Natural Gas Customers Serviced By Tenancy In Common Pertains to the estimated number of natural gas customers located near Dayton in west central Ohio serviced by the Ohio operations. Majority ownership percentage of Ohio operations owned as a tenancy in common by Vectren Energy Delivery of Ohio, Inc., a wholly owned subsidiary of Vectren Utility Holdings, Inc. (in hundredths) Majority Ownership Percentage Of Tenancy In Common Owned By Wholly Owned Subsidiary Of Subsidiary Holding Company Pertains to the percentage of Ohio operations owned as a tenancy in common by Vectren Energy Delivery of Ohio, Inc., a wholly owned subsidiary of Vectren Utility Holdings, Inc. Minority ownership percentage of Ohio operations owned as a tenancy in common by Indiana Gas, a subsidiary of Vectren Utility Holdings, Inc. (in hundredths) Minority Ownership Percentage Of Tenancy In Common Owned By Wholly Owned Subsidiary Of Subsidiary Holding Company Pertains to the percentage of Ohio operations owned as a tenancy in common by Indiana Gas, a wholly owned subsidiary of Vectren Utility Holdings, Inc. Number of Primary Business Areas Represents the number of primary business areas the entity has nonutility activities. Organization and Nature of Operations Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Schedule of Equity Method Investment, Equity Method Investee, Name [Axis] Schedule of Equity Method Investment, Equity Method Investee, Name [Axis] Equity Method Investee, Name [Domain] Equity Method Investee, Name [Domain] Proliance Holdings Llc [Member] Proliance Holdings Llc [Member] Information related to the legal entity ProLianceHoldings, LLC. Equity method investment, profit and loss ownership percentage (in hundredths) Equity Method Investment Profit And Loss Ownership Percentage The percentage of profit and loss the investee accounted for under the equity method of accounting. Equity method investment, ownership percentage (in hundredths) Equity Method Investment, Ownership Percentage Summarized statement of income information [Abstract] Equity Method Investment, Summarized Financial Information, Gross Profit (Loss) [Abstract] Revenues Equity Method Investment, Summarized Financial Information, Revenue Operating income (loss) Equity Method Investment, Summarized Financial Information, Gross Profit (Loss) Charge related to investment in Liberty Gas Storage EquityMethodInvestmentSummarizedFinancialInformationChargeRelatedToInvestmentInGasStorage The impairment charge recorded by one of the company's equity method investments for an investment held by that equity method investment. ProLiance's earnings (loss) Equity Method Investment, Summarized Financial Information, Income (Loss) from Continuing Operations before Extraordinary Items Summarized balance sheet information [Abstract] Equity Method Investment Summarized Balance Sheet Information [Abstract] Current assets Equity Method Investment, Summarized Financial Information, Current Assets Noncurrent assets Equity Method Investment, Summarized Financial Information, Noncurrent Assets Current liabilities Equity Method Investment, Summarized Financial Information, Current Liabilities Noncurrent liabilities Equity Method Investment, Summarized Financial Information, Noncurrent Liabilities Members' equity Equity Method Investment Summarized Financial Information Members Equity The amount of equity (capital) attributable to the equity method investment of the entity excluding accumulated other comprehensive income and noncontrolling interest. Accumulated other comprehensive income (loss) Equity Method Investment Summarized Financial Information Accumulated Other Comprehensive Income The amount of accumulated other comprehensive income (loss) reported by an equity method investee. Noncontrolling Interest Equity Method Investment, Summarized Financial Information, Noncontrolling Interest Equity method investment holding minority interest in equity method investment (in hundredths) Equity Method Investment Minority Interest Ownership Percentage By Noncontrolling Owners The equity interest of noncontrolling equity method investment shareholders, partners or other equity holders in consolidated entity. Equity method investment minority interest in joint ventures Equity Method Investment Minority Interest In Joint Ventures Equity investees material investment balance of a specific investee. Impairment charge recorded by an investee of the company's equity method investments Impairment charge recorded by an investee of the companys equity method investments The impairment charge recorded by an investee of the company's equity method investments. Impairment charge recorded by one of the companies equity method investments The impairment charge recorded by one of the companies equity method investments. Loss contingency, gross damages sought from a party that entered into a sub-lease agreement with a party that is an investment of an equity method investee Loss Contingency Gross Damages Sought For Sub Lease Agreement Loss contingency of an investment of an equity method investee, resulting from litigation surrounding allegations by a third party that is an investment of an equity method investee was negligent in performance of certain oblications under a sublease agreement. Purchases from ProLiance for resale and for injections into storage Related Party Transaction, Expenses from Transactions with Related Party Amounts owed to ProLiance for those purchases Accounts Payable Affiliated Company 1 Current Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to an affiliated company for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Subsequent event, equity method investment declaration of dividend payable Subsequent Event Equity Method Investment Dividend Payable Amount Reflects the known or estimated financial effect of the event, or transaction that occurred between the balance sheet date and the date the financial statements are issued. If an estimate cannot be made, that fact shall be disclosed. Equity Method Investment, Dividends or Distributions Environmental Matters Environmental Matters Disclosure [Text Block] Disclosures regarding environmental matters impacting the Company. Schedule of Long-term Debt Instruments [Table] Vectren Utility Holdings Inc [Member] Information related to the wholly owned subsidiary, Vectren Utility Holdings, Inc. Vectren Capital [Member] Vectren Capital [Member] Vectren Capital [Member] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Unsecured Debt [Member] Term Loan [Member] Term Loan [Member] Term Loan [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Senior Guaranteed Note due 2021 [Member] Senior guaranteed note due November 30, 2021 with a stated interest rate of 4.67%. Senior Guaranteed Note due 2026 [Member] Senior guaranteed note due November 30, 2026 with a stated interest rate of 5.02%. Senior Guaranteed Note due 2041 [Member] Senior guaranteed note due December 2, 2041 with a stated interest rate of 5.99%. Senior Guaranteed Note due 2036 [Member] Senior guaranteed note due 2036 with a stated interest rate of 5.95%. Senior Guaranteed Note due 2011 [Member] Senior guaranteed note due December 1, 2011 with a stated interest rate of 6.625% Senior Guaranteed Note due 2042 [Member] Senior Guaranteed Note due 2042 [Member] Senior guaranteed note due 2042 with a stated interest rate of 5.0%. Debt Instrument [Line Items] Face amount Debt Instrument, Face Amount Stated percentage rate (in hundredths) Debt Instrument, Interest Rate, Stated Percentage Maturity date Debt Instrument, Maturity Date Maturity date year Debt Instrument Maturity Date Year Date when the debt instrument is scheduled to be fully repaid by year Issuance date Debt Instrument, Issuance Date Loan term (in years) Loan term (in years) Loan term (in years) Term loan interest rate Term loan interest rate Term loan interest rate Proceeds from Issuance of Debt Call date Debt Instrument Call Date Planned The date on which the issuer plans to call the outstanding debt for repayment or conversion to equity which may be presented in a variety of ways. Current portion of long-term debt that will either be refinanced or retired. Current portion of long-term debt that will either be refinanced or retired Current portion of long-term debt that will either be refinanced or retired. Amount of current debt that has been reclassified to long-term debt to reflect the company's ability and intent to refinance from the proceeds received from the issuance of the senior notes Amount of current debt that has been reclassified to long-term debt The amount of current debt that has been reclassified to long-term debt to reflect the company's ability and intent to refinance from the proceeds received from the issuance of the senior notes. Fair Value Measurements Fair Value Disclosures [Text Block] Legislative Matters [Table] Legislative Matters, by legislative action [Axis] Legislative Matters By Legislative Action [Axis] Information on legislative actions affecting the business of the Company. Legislative Action, Name [Domain] Legislative Action Name [Domain] Pipeline Safety Law [Member] Information on the Pipeline Safety, Regulatory Certainty and Job Creation Act of 2011 and its impact on the Company. Indiana House Bill 1004 [Member] Indiana House Bill1004 [Member] Information on the Indiana House Bill 1004. Indiana Senate Bill 251 [Member] Indiana Senate Bill 251 [Member] Ohio House Bill 95 [Member] Ohio House Bill95 [Member] Information on the Ohio House Bill 95. Operations, by State [Axis] Operation By State [Axis] Information on the impact of the legislation by the state in which the operations occur. State Name [Domain] State name domain. Indiana [Member] Information on activities in the state of Indiana. Ohio [Member] Legislative Matters [Line Items] Description of legislation Description Of Legislation A description of the legislation that would apply to several proposed federal mandates. Description of the goal of legislation Description Of Goal Of Program A description of the goal of the program. Estimated amount of operating expenses that could accumulate associated with expanded compliance requirements Estimated Amount Of Operating Expense Associated With Expanded Compliance The estimated amount of operating expenses that could accumulate associated with the expanded compliance requirements. Estimated amount that would qualify for timely recovery Estimated Amount That Would Qualify For Timely Recovery The estimated amount of the additional expenses that would qualify for timely recovery. Capital expenditures driven by the legislation Capital Expensditures Driven By Legislation The estimated amount of capital expenditures that could accumulate associated with the expanded compliance requirements. Period over which capital expenditures would accumulate (in years) Period Over Which Capital Expenditures Would Accumulate The estimated period over which the expected capital expenditures would accumulate. Estimated incremental operating expenses that would not be recoverable without a rate proceeding Estimated Incremental Operating Expenses Not Recoverable Without Rate Proceeding The estimated amount of incremental operating expenses that would be required under the legislation but would not be recoverable without a rate proceeding. Decrease In Regulatory Asset, Deferred Tax Liabilities Decrease In Regulatory Asset Deferred Tax Liabilities Cost Of Deferred Capital Expenditure Program Cost Of Defered Capital Expenditure Program Pension and Other Postretirement Benefit Expense [Abstract] Schedule of Defined Benefit Plans Disclosures [Table Text Block] Basis of Presentation [Abstract] Basis of Presentation Basis of Presentation [Text Block] The entire disclosure for the basis of presentation. Statement of Income and Comprehensive Income [Abstract] Other comprehensive income (loss), before tax [Abstract] Other Comprehensive Income (Loss), before Tax [Abstract] Comprehensive income of unconsolidated affiliates Comprehensive Income Loss Of Unconsolidated Affiliates Before Tax Other comprehensive income of equity method investees, before tax Remeasurement of postretirement benefit obligation RemeasurementOfPostretirementBenefitObligation Effect of remeasurement of postretirement benefit obligation Cash flow hedges Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, before Tax Other comprehensive income (loss), before tax Other Comprehensive Income (Loss), before Tax Income taxes related to items of other comprehensive income Other Comprehensive Income (Loss), Tax Other comprehensive income (loss), net of tax Other Comprehensive Income (Loss), Net of Tax Total comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Rate and Regulatory Matters [Abstract] Rate and Regulatory Matters Public Utilities Disclosure [Text Block] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Statement of Cash Flows [Abstract] CASH FLOWS FROM OPERATING ACTIVITES [Abstract] Net Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Deferred income taxes & investment tax credits Deferred Income Taxes and Tax Credits Equity in losses of unconsolidated affiliates Provision for uncollectible accounts Provision for Doubtful Accounts Expense portion of pension & postretirement benefit cost Pension and Other Postretirement Benefit Expense Other noncash charges - net Other Noncash Income (Expense) Changes in working capital accounts [Abstract] Increase (Decrease) in Operating Capital [Abstract] Accounts receivable & accrued unbilled revenues Increase (Decrease) in Accounts receivable and accrued unbilled revenues The net change during the reporting period in amount due within one year (or one business cycle) from customers for the credit sale of goods and services. Also includes, the net change during the reporting period the amount of revenue for work performed for which the billing milestone has not occurred, net of uncollectible accounts. Inventories Increase (Decrease) in Inventories Recoverable/refundable fuel & natural gas costs Increase (Decrease) in Recoverable Refundable Gas Costs Prepayments & other current assets Increase (Decrease) in Prepaid Expense and Other Assets Accounts payable, including to affiliated companies Increase (Decrease) in Accounts Payable Accrued liabilities Increase (Decrease) in Accrued Liabilities Unconsolidated affiliate dividends Cash Dividends Paid to Parent Company by Unconsolidated Subsidiaries Employer contributions to pension & postretirement plans Pension and Other Postretirement Benefit Contributions Changes in noncurrent assets Increase (Decrease) in Other Operating Assets Changes in noncurrent liabilities Increase (Decrease) in Other Operating Liabilities Net cash flows from operating activities Net Cash Provided by (Used in) Operating Activities CASH FLOWS FROM FINANCING ACTIVITIES [Abstract] Net Cash Provided by (Used in) Financing Activities [Abstract] Proceeds from: Proceeds From Financing Activities [Abstract] Long-term debt, net of issuance costs Proceeds from Issuance of Long-term Debt Dividend reinvestment plan & other common stock issuances Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options Requirements for: Requirements For Financing Activities [Abstract] Dividends on common stock Payments of Dividends, Common Stock Retirement of long-term debt Repayments of Long-term Debt Other financing activities Proceeds from (Payments for) Other Financing Activities Net change in short-term borrowings Proceeds from (Repayments of) Short-term Debt Net cash flows from financing activities Net Cash Provided by (Used in) Financing Activities CASH FLOWS FROM INVESTING ACTIVITIES [Abstract] Net Cash Provided by (Used in) Investing Activities [Abstract] Proceeds from: Proceeds from Investing Activities [Abstract] Unconsolidated affiliate distributions Proceeds from (Payments to) Noncontrolling Interests Other collections Proceeds from Collection of Other Receivables Requirements for: Requirements For Investing Activities [Abstract] Capital expenditures, excluding AFUDC equity Payments to Acquire Property, Plant, and Equipment Business acquisition, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Unconsolidated affiliate investments Payments to Acquire Equity Method Investments Other investments Payments to Acquire Other Investments Net cash flows from investing activities Net Cash Provided by (Used in) Investing Activities Net change in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Schedule of Guarantor Obligations [Table] Schedule of Guarantor Obligations [Table] Guarantor Obligations by Nature [Axis] Guarantor Obligations by Nature [Axis] Guarantor Obligations, Nature [Domain] Guarantor Obligations, Nature [Domain] Performance Guarantee [Member] Performance Guarantee [Member] Other Guarantees Outstanding [Member] Guarantee Type, Other [Member] Financial Standby Letter of Credit [Member] Financial Standby Letter of Credit [Member] Guarantor Obligation Related Party [Axis] Guarantor Obligation Related Party [Axis] Pertinent information and amount of guarantee, relating to wholly owned subsidiaries and unconsolidated affiliates. Guarantor Obligations by Related Party [Domain] Guarantor Obligations by Related Party [Domain] Guarantees for ESG [Member] Guarantees for ESG [Member] Guarantees relating to the firm's wholly owned subsidiary ESG. Guarantees for Other Unconsolidated Affiliates [Member] Guarantees for Other Unconsolidated Affiliates [Member] Guarantees relating to the firm's other unconsolidated affiliates and wholly owned subsidiaries. Guarantees for Vectren Source [Member] Guarantees for Vectren Source [Member] Guarantees relating to the wholly owned subsidiary Vectren Source. Guarantor Obligations [Line Items] Guarantor Obligations [Line Items] Corporate Guarantees [Abstract] Guarantees [Abstract] Maximum exposure by parent company on guarantees Guarantor Obligations, Maximum Exposure, Undiscounted Performance Guarantees and Product Warranties [Abstract] Performance Guarantees Product Warranties [Abstract] Number of surety bonds wholly owned subsidiary has outstanding in role as general contractor (in number of surety bonds) Number Of Surety Bond Obligations Outstanding For Wholly Owned Subsidiary Represents the absolute number of surety bonds the wholly owned subsidiary has outstanding in its role as general contractor Average face amount of surety bonds wholly owned subsidiary has outstanding Performance Guarantee Obligations Outstanding Average Face Amount Represents the average face amount of individual surety bonds the wholly owned subsidiary has outstanding. Maximum face amount of surety bond wholly owned subsidiary has outstanding Performance Guarantee Obligations Outstanding Maximum Face Amount Represents the maximum face amount of an individual surety bond a wholly owned subsidiary has outstanding. Percentage of work completed on projects covered by open surety bonds (in hundredths) Percentage Of Work Completed On Projects With Open Surety Bonds Percentage of work completed on projects covered by open surety bonds. Timeframe when significant portion of performance guarantee commitments will be fulfilled Purchase Guarantee Obligations Term Remaing For Significant Portion To Be Fulfilled Term remaining for a significant portion of the purchase guarantee obligations to be fulfilled. Maximum exposure by parent company on other projects' guarantees Guarantee Obligations Of Single Subsidiary Other Project Guarantee Maximum Exposure By Parent Company Maximum parent company guarantee of a single subsidiary's other project guarantees. Guarantor Obligations, Maximum Exposure, Undiscounted Guarantee Obligations Of Other Operating Company Operations By Parent Company Parent company guarantees of other operating company operations. Guarantor Obligations Nonregulated retail gas supply operations, Maximum Exposure, Undiscounted Guarantee Obligations Supporting Nonutility Retail Gas Operations By Parent Company Of the Parent company guarantees of other operating company operations, these guarantees support nonutility retail gas supply operations. Guarantor Obligations unconsolidated affiliates, Maximum Exposure, Undiscounted Guarantee Obligations Supporting Unconsolidated Affiliate Operations By Parent Company Parent company guarantees that support operations of unconsolidated affiliates. Letters of credit, nonutility operations Letters Of Credit Supporting Nonutility Operations By Parent Company Of the Parent company guarantees of other operating company operations, these company issued letters of credit support nonutility operations. Time period of warranty of functionality of certain installed infrastructure (in years) Product Performance Warranty Period Infrastructure Period that infrastructure is covered by product performance warranty. Basic and dilutive EPS Schedule of Calculation of Numerator and Denominator in Earnings Per Share [Table Text Block] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Domain] Pension Benefits [Member] Pension Plans, Defined Benefit [Member] Other Benefits [Member] Other Postretirement Benefit Plans, Defined Benefit [Member] Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Number of qualified defined benefit pension plans Number of qualified defined benefit pension plans1 Number of other postretirement benefit plans Number of other postretirement benefit plans 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 Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Amortization of transitional obligation Defined Benefit Plan, Amortization of Transition Obligations (Assets) Amortization of actuarial loss Defined Benefit Plan, Amortization of Gains (Losses) Net periodic benefit cost Defined Benefit Plan, Net Periodic Benefit Cost Expected contribution to defined benefit plans for current year by employer Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year Contribution to date to defined benefit plans by employer Defined Benefit Plan, Contributions by Employer Discount rate for remeasurement Discount rate for remeasrurement Discount rate for remeasrurement of post-retirement benefit obligation Decrease in recorded liability from remeasurement of post-retirement benefit obligation DecreaseInRecordedLiabilityFromRemeasurement Decrease in recorded liability from remeasurement of post-retirement benefit obligation. Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Retirement Plans and Other Postretirement Benefits Pension and Other Postretirement Benefits Disclosure [Text Block] Vectren South Electric Base Rate Filing [Abstract] Amount of revised rate increase filed in rebuttal to original rate increase to IURC Base Rate Increase Filed With Iurc For Capital Investments Amount of rate increase, SIGECO filed with IURC, over current rates to cover the cost of capital investment and energy efficiency efforts. Amount of infrastructure construction in the three years leading up to December 2009 rate filing Amount of capital investment by SIGECO Amount of capital investment by SIGECO in the three years leading up to December 2009 rate filing. Rate of return included in rate increase (in hundredths) Rate Of Return On Rate Base The overall rate of return included in SIGECO's rate base. Dollar amount of the rate base included in rate increase Amount of rate base included in rate increase Amount of rate base for service area included in Sigeco's rate increase. Amount of rate of return on equity included in rate base (in hundredths) Amount of rate of return on equity included in rate base (in hundredths) The percentage of rate of return on equity included in SIGECO's rate base. Authorized increase in revenue from utility service SIGECO's authorized increase in revenue from utility service approved by Indiana Utility Regulatory Commission. Number Of Years Recovery Of Regulatory Asset The period of time for the recovery of the regulatory asset. Period in which recovery begins Period In Which Recovery Begins The period in which the recovery of a regulatory asset begins. Vectren South Electric Fuel Cost Reduction [Abstract] Vectren South Electric Fuel Cost Reduction Number of years for recovery of coal costs Number of years for recovery of coal costs Reduction to coal inventory balance related to deferral Reduction to coal inventory balance related to deferral Reduction of coal inventory balance related to cost deferrals to reflect existing inventory at the new lower price. Deferrals related to coal purchases in the current year Deferrals related to coal purchases in the current year Deferrals related to coal purchases in the current year Cumulative total deferrals related to coal purchases Cumulative total deferrals related to coal purchases Cumulative total deferrals related to coal purchases Vectren South Electric Demand Side Management Program Filing [Abstract] Vectren South Electric Demand Side Management Program Filing Number of years in initial demand side management program approved by the IURC (in years) Number Of Years In Initial Demand Side Management Program The number of years in the initial demand side management program approved by IURC. Maximum deferral of lost margin associated with small customer demand side programs Maximum Deferral Of Lost Margin Associated With Small Customer Demand Side Programs The maximum deferral of lost margin associated with small customer demand side management programs for subsequent recovery in a tracking mechanism to be proposed by the Company Vectren South Electric Dense Pack Filing [Abstract] Expected capital investment to improve the efficiency of generating station Expected Capital Investment To Improve Efficiency Of Generating Station The amount of the expected capital investment over two years to improve the efficiency of one of its generating stations. Number of years in capital improvement program (in years) Number Of Years In Capital Improvement Program The length of time the capital improvement project at one of its generating stations is expected to last. Amount of expected capital investment invested to date Amount Of Expected Capital Investment Invested To Date The amount of the expected capital investment spent to date to improve the efficiency of one of its generating stations. Expected increase in efficiency for generating station following improvement (in hundredths) Expected Increase In Efficiency For Generating Station Following Improvement The expected increase in the efficiency of the generating station following the capital improvement project completion. VEDO Continues the Process to Exit the Merchant Function [Abstract] Process to Exit Merchant Function [Abstract] Length of contract for customers who purchase natural gas through state certified natural gas suppliers (in months) Length of Supplier Contract For Natural Gas Customer Fixed term of contract (in months) for suppliers of natural gas to customers before another auction has to take place. Number of auctions requirement related to the plan approved by the PUCO (in number of auctions) Number Of Auctions Requirement Related To Plan Approved By Puco In Number Of Auctions Pertains to the number of auctions requirement related to the plan approved by the PUCO related to VEDO's exit the merchant function. Number of tranches of customers secured in first auction Number Of Tranches Of Customers Secured In First Auction The number of tranches of customers secured in first auction. Number of tranches of customers secured in second auction Number Of Tranches Of Customers Secured In Second Auction The number of tranches of customers secured in second auction. Approximate Number Of Customers In Tranche The approximate number of customers contained in tranche of customers. VEDO Gas Rate Design [Abstract] VEDO Gas Base Rate Order Received [Abstract] Rate increase provided for by PUCO The approved increase in gas base rates as ordered by the state regulatory commission. Rate of return provided by approved rate increase (in hundredths) The approved rate of return on assets (rate base) as ordered by the state regulatory commission in the gas base rate case. Base rate recovery of conservation program spending The incremental costs related to gas conservation programs included for recovery in gas base rate case as ordered by the state regulatory commission. Revenue from the decoupling mechanism that did not continue The amount of revenues in 2008 related to the commission approved decoupling mechanism. As a result of the order in the gas base rate case effective in 2009, these decoupling revenues (from 2008) will not continue. Percentage of residential and commercial base rate covered by customer service charge (in hundredths) Customer Percentage Covered By Customer Service Charge Total percentage of customer revenues recovered via fixed gas rates as opposed to volumetric rates. Other cases Other court cases in which Ohio Supreme court had affirmed PUCO orders authorizing straight fixed variable rate design Annual expenditures of expanded conservation program Total annual expenditures included in rates related to gas conservation programs. Vectren North Gas Base Rate Order Received [Abstract] Gas Base Rate Order Received [Abstract] Cost recovery provided for separately Cost recovery provided for seperately Cost recovery provided for through separate cost recovery means other than base rate adjustments. Annual expenditures limit for special accounting treatment Annual expenditures limit for special accounting treatment. Limitation of special accounting treatment (in years) Limitation of special accounting treatment (in years)