Revenue from Contract with Customer [Abstract] Revenue, Initial Application Period Cumulative Effect Transition [Table] Revenue, Initial Application Period Cumulative Effect Transition [Table] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2014-09 Accounting Standards Update 2014-09 [Member] Initial Application Period Cumulative Effect Transition [Axis] Initial Application Period Cumulative Effect Transition [Axis] Initial Application Period Cumulative Effect Transition [Domain] Initial Application Period Cumulative Effect Transition [Domain] Calculated under Revenue Guidance in Effect before Topic 606 Calculated under Revenue Guidance in Effect before Topic 606 [Member] Difference between Revenue Guidance in Effect before and after Topic 606 Difference between Revenue Guidance in Effect before and after Topic 606 [Member] Revenue, Initial Application Period Cumulative Effect Transition [Line Items] Revenue, Initial Application Period Cumulative Effect Transition [Line Items] Accrued unbilled revenues Accrued unbilled revenues Unbilled amounts due for services rendered or products shipped. Also includes cost of uncompleted contracts in excess of related billings, or unbilled accounts receivable, which is expected to be collected within one year (or one operating cycle, if longer) from the date of the balance sheet. Prepayments & other current assets Prepaid Expense and Other Assets, Current Accrued liabilities Accrued Liabilities, Current Retained earnings Retained Earnings (Accumulated Deficit) Segment Reporting [Abstract] Schedule of Segment Reporting Information, by Segment [Table] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Operating Segments Operating Segments [Member] Eliminations Intersegment Eliminations [Member] Corporate & Other Group Corporate, Non-Segment [Member] Eliminations Consolidation, Eliminations [Member] Segments [Axis] Segments [Domain] Utility Group Utility Group [Member] Nonutility Group Nonutility Group [Member] Nonutility Group Subsegments [Axis] Subsegments [Axis] Subsegments [Domain] Subsegments [Domain] Gas Utility Services Gas Utility Services [Member] Electric Utility Services Electric Utility Services [Member] Other Operations Parent [Member] Infrastructure Services Infastructure Services [Member] Energy Services Energy Services [Member] Other Nonutility Businesses Other Businesses [Member] Segment Reporting Information [Line Items] Revenues Revenue, Net Net income Net Income (Loss) Attributable to Parent Excise and Utility Receipts Taxes [Abstract] Excise & 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. Schedule of Segment Reporting Information, by Segment [Table] Segments [Axis] Segments [Domain] Segment Reporting Information [Line Items] Number of operational groups Number Of Operating Groups Number Of Operating Groups 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 customers (greater than) Number of Customers Number of Customers Number of operating segments Number of Operating Segments Fees incurred for pipeline construction and repair services Related Party Transaction, Expenses from Transactions with Related Party Fair Value Disclosures [Abstract] Fair Value, by Balance Sheet Grouping [Table] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement [Member] Portion at Fair Value Measurement [Member] Carrying Amount Reported Value Measurement [Member] Est. Fair Value Estimate of Fair Value Measurement [Member] Financial Instrument [Axis] Financial Instrument [Axis] Financial Instruments [Domain] Financial Instruments [Domain] Forward Contracts Forward Contracts [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Long-term debt Long-term Debt, Fair Value Short-term borrowings Short-term Debt, Fair Value Cash & cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Natural gas purchase instrument assets Derivative Asset, Noncurrent Natural gas purchase instrument liabilities Derivative Liability, Noncurrent Interest rate swap assets Interest Rate Derivative Assets, at Fair Value Interest rate swap liabilities Interest Rate Derivative Liabilities, at Fair Value Forward purchase arrangements, term Derivative, Term of Contract Carrying Value of investments not practical to estimate fair value Notes Receivable, Fair Value Disclosure Supplemental Cash Flow Information [Abstract] Accruals related to utility and nonutility plant purchases Capital Expenditures Incurred but Not yet Paid Earnings Per Share [Abstract] Basic and Dilutive EPS Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Equity Method Investments and Joint Ventures [Abstract] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Maximum Maximum [Member] Minimum Minimum [Member] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Investments in unconsolidated affiliates Investments In Unconsolidated Affiliates [Member] Investments In Unconsolidated Affiliates [Member] Other nonutility investments Prepaid Expenses and Other Current Assets [Member] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] Proliance Holdings LLC Proliance Holdings Llc [Member] Information related to the legal entity ProLianceHoldings, LLC. LA Storage LA Storage [Member] LA Storage [Member] Consolidated Entities [Axis] Consolidated Entities [Axis] Consolidated Entities [Domain] Consolidated Entities [Domain] Affiliated Entity Affiliated Entity [Member] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Ownership share (as a percent) Equity Method Investment, Ownership Percentage Voting rights (as a percent) Equity Method Investment, Voting and Governance Rights Equity method investment, voting and governance rights Summarized balance sheet information [Abstract] Equity Method Investment, Summarized Financial Information [Abstract] Cash Equity method investment, Summarized Financial Information, Cash The amount of cash reported by an equity method investment of the entity. Investment in LA Storage Equity Method investment, Summarized Financial Information, Storage Assets The amount of the storage assets reported by an equity method investment of the entity. Total investment in ProLiance Equity method investment, gross investment in equity method investee Equity method investment, gross investment in equity method investee Investment in Proliance Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Ownership interest (as a percent) Combined Joint Venture Ownership Percentage Equity method investment, combined joint venture ownership percentage Storage capacity Project Storage Capacity Project Storage Capacity FERC certified caverns, fully tested with additional work to further develop FERC Certified Caverns, Fully Tested With Additional Work To Further Develop FERC Certified Caverns, Fully Tested With Additional Work To Further Develop FERC certified caverns FERC Certified Caverns FERC Certified Caverns Investment in joint venture Equity Method Investments Summarized Financial Information of Equity Investment Summarized Financial Information of Equity Investment [Table Text Block] Tabular disclosure of financial information of ProLiance Holdings, LLC. Accounting Policies [Abstract] Impact of Recently Issued Accounting Standards New Accounting Pronouncements and Changes in Accounting Principles [Text Block] Fair Value By Balance Sheet Grouping Fair Value, by Balance Sheet Grouping [Table Text Block] Fair Value Measurements Fair Value Disclosures [Text Block] Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract] Retirement Plans & Other Postretirement Benefits Pension and Other Postretirement Benefits Disclosure [Text Block] Income Tax Disclosure [Abstract] Income Taxes Income Tax Disclosure [Text Block] Public Utilities, General Disclosures [Abstract] Gas Rate & Regulatory Matters Public Utilities General Disclosures - Gas [Text Block] Public Utilities General Disclosures - Gas [Text Block] Recently Issued Accounting Policies New Accounting Pronouncements, Policy [Policy Text Block] Revenue Revenue from Contract with Customer [Text Block] Income Statement [Abstract] OPERATING REVENUES Revenue, Net [Abstract] Gas utility Regulated Operating Revenue, Gas Electric utility Electric Domestic Regulated Revenue Nonutility Other Revenue, Net Total operating revenues OPERATING EXPENSES Operating Expenses [Abstract] Cost of gas sold Cost of Natural Gas Purchases 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 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 Nonoperating Income (Expense) INTEREST EXPENSE Interest Expense INCOME BEFORE INCOME TAXES Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest INCOME TAXES Income Tax Expense (Benefit) NET INCOME AND COMPREHENSIVE INCOME WEIGHTED AVERAGE AND DILUTED COMMON SHARES OUTSTANDING (in shares) Weighted Average Number of Shares Outstanding, Basic and Diluted BASIC AND DILUTED EARNINGS PER SHARE OF COMMON STOCK (in dollars per share) Earnings Per Share, Basic and Diluted DIVIDENDS DECLARED PER SHARE OF COMMON STOCK (in dollars per share) Common Stock, Dividends, Per Share, Declared Basis of Presentation [Abstract] Basis of Presentation Basis of Presentation and Significant Accounting Policies [Text Block] Earnings Per Share Earnings Per Share [Text Block] Schedule of New Accounting Pronouncements Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block] Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Summary of Contract Liabilities Contract with Customer, Asset and Liability [Table Text Block] Summary of Remaining Performance Obligations Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table Text Block] Commitments and Contingencies Disclosure [Abstract] Schedule of Guarantor Obligations [Table] Schedule of Guarantor Obligations [Table] Energy Systems Group Energy Systems Group [Member] Energy Systems Group [Member] Guarantor Obligations by Nature [Axis] Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Domain] Guarantor Obligations, Nature [Domain] Performance Guarantee Performance Guarantee [Member] Guarantor Obligations [Line Items] Guarantor Obligations [Line Items] Corporate Guarantees [Abstract] Guarantees [Abstract] Performance Guarantees and Product Warranties [Abstract] Performance Guarantees Product Warranties [Abstract] Number of surety bonds open to support future performance 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 Face amount of surety bonds outstanding Performance Guarantee Obligations Outstanding Face Amount Face amount of individual surety bonds the wholly owned subsidiary has outstanding. Work yet to be completed on surety bond projects (as a percent) Percentage Of Work Yet to be Completed On Projects With Open Surety Bonds Percentage of work yet to be completed on projects with open surety bonds Period for release of significant portion of surety bonds Guarantor Obligation Term Guarantor Obligation Term Warranty liability recognized Standard and Extended Product Warranty Accrual Maximum exposure by parent company on guarantees Guarantor Obligations, Maximum Exposure, Undiscounted Letters of credit outstanding Letters of Credit Outstanding, Amount Firm purchase commitment term one Purchase Commitment Contract Term One Purchase Commitment Contract Term One Firm purchase commitment term two Purchase Commitment Contract Term Two Purchase Commitment Contract Term Two Debt Disclosure [Abstract] Financing Activities Debt Disclosure [Text Block] Document and Entity Information [Abstract] 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 Investment in ProLiance Holdings, LLC Equity Method Investments and Joint Ventures Disclosure [Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization and Nature of Operations Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Segment Reporting Segment Reporting Disclosure [Text Block] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Products and Services [Axis] Products and Services [Axis] Products and Services [Domain] Products and Services [Domain] Construction Construction [Member] Construction [Member] Operations and Maintenance and other Operations And Maintenance And Other [Member] Operations And Maintenance And Other [Member] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Revenue from contract with customers Revenue from Contract with Customer, Excluding Assessed Tax Schedule of Segment Reporting Schedule of Segment Reporting Information, by Segment [Table Text Block] Summary of Net Periodic Benefit Costs Schedule of Defined Benefit Plans Disclosures [Table Text Block] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Retirement Plan Type [Axis] Retirement Plan Type [Axis] Retirement Plan Type [Domain] Retirement Plan Type [Domain] Pension Benefits Pension Plan [Member] Other Benefits Other Postretirement Benefits Plan [Member] Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Service cost Defined Benefit Plan, Service Cost Interest cost Defined Benefit Plan, Interest Cost Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Amortization of prior service cost Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Amortization of actuarial loss Defined Benefit Plan, Amortization of Gain (Loss) Net periodic cost (benefit) Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Numerator: Numerator [Abstract] Reported net income (Numerator for Basic and Diluted EPS) Denominator: Denominator [Abstract] Weighted-average common shares outstanding (in dollars per share) Basic and Diluted EPS (in dollars per share) Contract assets Contract with Customer, Asset, Net Accounts Receivable Change In Accounts Receivable, Accrued Unbilled Revenue, and Contract Liability [Roll Forward] Change In Accounts Receivable, Accrued Unbilled Revenue, and Contract Liability [Roll Forward] Opening (01/01/2018) Accounts Receivable, Net, Current Increase (decrease) in accounts receivable Increase (Decrease) in Accounts Receivable Closing (03/31/2018) Accrued Unbilled Revenues Change In Accrued Unbilled Revenue [Roll Forward] Change In Accrued Unbilled Revenue [Roll Forward] Opening (01/01/2018) Increase (decrease) in accrued unbilled revenues Increase (Decrease) In Accrued Unbilled Revenues Increase (Decrease) In Accrued Unbilled Revenues Closing (03/31/2018) Contract Liabilities Change In Contract Liability [Roll Forward] Change In Contract Liability [Roll Forward] Opening (01/01/2018) Contract with Customer, Liability Increase (decrease) in contract liability Contract With Customer, Liability Increase (Decrease) Contract With Customer, Liability Increase (Decrease) Closing (03/31/2018) Infrastructure Services Infrastructure Services [Member] Infrastructure Services Reduction to retained earnings Contract with customer, liability, revenue recognized Contract with Customer, Liability, Revenue Recognized Residential Residential Revenue [Member] Residential [Member] Commercial Commercial Revenue [Member] Commercial Revenue [Member] Industrial Industrial Revenue [Member] Industrial Revenue [Member] Other Other Revenue [Member] Other Revenue [Member] Excise and utility receipts taxes billed to customers Excise Taxes Collected Statement of Financial Position [Abstract] ASSETS Assets [Abstract] Current Assets Assets, Current [Abstract] Cash & cash equivalents Cash and Cash Equivalents, at Carrying Value Accounts receivable - less reserves of $6.5 & $5.1, respectively Inventories Inventory, Net Recoverable fuel & natural gas costs Deferred Fuel Cost Total current assets Assets, Current Utility Plant 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 Other utility & corporate investments Other Investments 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 Goodwill Regulatory assets Regulatory Assets, Noncurrent Other assets Other Assets, Noncurrent TOTAL ASSETS Assets LIABILITIES & SHAREHOLDERS' EQUITY Liabilities and Equity [Abstract] Current Liabilities Liabilities, Current [Abstract] Accounts payable Accounts Payable, Current Short-term borrowings Short-term Debt Current maturities of long-term debt Long-term Debt, Current Maturities Total current liabilities Liabilities, Current Long-term Debt - Net of Current Maturities Long-term Debt, Excluding Current Maturities Deferred Credits & Other Liabilities Liabilities, Noncurrent [Abstract] Deferred income taxes Deferred Income Tax Liabilities, Net Regulatory liabilities Regulatory Liability, Noncurrent Deferred credits & other liabilities Deferred Credits and Other Liabilities Total deferred credits & other liabilities Liabilities, Noncurrent Commitments & Contingencies (Notes 8, 11-14) Commitments and Contingencies Common Shareholders' Equity Stockholders' Equity Attributable to Parent [Abstract] Common stock (no par value) – issued & outstanding 83.1 & 83.0, respectively Common Stock, Value, Issued Accumulated other comprehensive (loss) Accumulated Other Comprehensive Income (Loss), Net of Tax Total common shareholders' equity Stockholders' Equity Attributable to Parent TOTAL LIABILITIES & SHAREHOLDERS' EQUITY Liabilities and Equity Line of Credit Facility [Table] Line of Credit Facility [Table] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Mortgages Mortgages [Member] Variable Rate Tax-Exempt Bonds Variable Rate Tax-Exempt Bonds [Member] Variable Rate Tax-Exempt Bonds [Member] Senior Notes Senior Notes [Member] SIGECO SIGECO [Member] Refers to an entity under the control of the same parent as another entity (that is, a sister company). Utility Holdings Vectren Utility Holdings Inc [Member] Information related to the wholly owned subsidiary, Vectren Utility Holdings, Inc. Vectren Capital Corp Vectren Capital Corp [Member] Refers to an entity under the control of the same parent as another entity (that is, a sister company). Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Series A Notes Due March 2038 Series A Notes Due March 2038 [Member] Series A Notes Due March 2038 [Member] Series B Notes Due May 2043 Series B Notes Due May 2043 [Member] Series B Notes Due May 2043 [Member] 2013 Series C Notes due 2022 2013 Series C Notes due 2022 [Member] 2013 Series C Notes due 2022 [Member] 2013 Series D Notes due 2024 2013 Series D Notes due 2024 [Member] 2013 Series D Notes due 2024 [Member] 2013 Series E Notes due 2037 2013 Series E Notes due 2037 [Member] 2013 Series E Notes due 2037 [Member] 2014 Series B Notes Due 2025 2014 Series B Notes Due 2025 [Member] 2014 Series B Notes Due 2025 [Member] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Bonds callable or called Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Maximum Amount Interest rate Debt Instrument, Interest Rate, Stated Percentage Long term debt, gross Long-term Debt, Gross Senior notes, face amount Debt Instrument, Face Amount Redemption price percent Debt Instrument, Redemption Price, Percentage Timing of Transfer of Good or Service [Axis] Timing of Transfer of Good or Service [Axis] Timing of Transfer of Good or Service [Domain] Timing of Transfer of Good or Service [Domain] Unit or time and material (point in time) Transferred at Point in Time [Member] Fixed price (over time) Transferred over Time [Member] Statement of Cash Flows [Abstract] CASH FLOWS FROM OPERATING ACTIVITIES Net Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income to cash from operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation & amortization Deferred income taxes & investment tax credits Deferred Income Taxes and Tax Credits Provision for uncollectible accounts Provision for Doubtful Accounts Expense portion of pension & postretirement benefit cost Pension and Other Postretirement Benefits Cost (Reversal of Cost) Other non-cash items - net Other Noncash Income (Expense) Changes in working capital accounts: Increase (Decrease) in Operating Capital [Abstract] Accounts receivable & accrued unbilled revenues Increase (Decrease) in Receivables 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 Increase (Decrease) in Accounts Payable Accrued liabilities Increase (Decrease) in Accrued Liabilities Employer contributions to pension & postretirement plans Payment for Pension and Other Postretirement Benefits Changes in noncurrent assets Increase (Decrease) in Other Operating Assets Changes in noncurrent liabilities Increase (Decrease) in Other Operating Liabilities Net cash from operating activities Net Cash Provided by (Used in) Operating Activities CASH FLOWS FROM FINANCING ACTIVITIES Net Cash Provided by (Used in) Financing Activities [Abstract] Long-term debt, net of issuance costs Proceeds from Debt, Net of Issuance Costs Dividend reinvestment plan & other common stock issuances Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options Requirements for dividends on common stock Payments of Ordinary Dividends, Common Stock Net change in short-term borrowings Proceeds from (Repayments of) Short-term Debt Net cash from financing activities Net Cash Provided by (Used in) Financing Activities CASH FLOWS FROM INVESTING ACTIVITIES Net Cash Provided by (Used in) Investing Activities [Abstract] Proceeds from sale of assets and 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 Changes in restricted cash Increase (Decrease) in Restricted Cash Net cash from investing activities Net Cash Provided by (Used in) Investing Activities Net change in cash & cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash & cash equivalents at beginning of period Cash & cash equivalents at end of period Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Energy Services - operations and maintenance Energy Services - Operations And Maintenance [Member] Energy Services - Operations And Maintenance [Member] Energy Services - construction Energy Services - Construction [Member] Energy Services - Construction [Member] Infrastructure Services - fixed price (bid) Infrastructure Services - Fixed Price (Bid) [Member] Infrastructure Services - Fixed Price (Bid) [Member] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Remaining performance obligation Revenue, Remaining Performance Obligation Remaining performance obligation period Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Public Utilities General Disclosures [Table] Public Utilities General Disclosures [Table] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] INDIANA INDIANA OHIO OHIO Public Utilities, Regulatory Proceeding [Axis] Public Utilities, Regulatory Proceeding [Axis] Public Utilities, Regulatory Proceeding [Domain] Public Utilities, Regulatory Proceeding [Domain] Indiana Recovery and Deferral Mechanisms Indiana Recovery and Deferral Mechanisms [Member] Indiana Recovery and Deferral Mechanisms [Member] Senate Bill 251 and 560 Senate Bill 251 and 560 [Member] Senate Bill 251 and 560 [Member] Senate Bill 251 Senate Bill 251 [Member] Senate Bill 251 [Member] Ohio Recovery and Deferral Mechanisms Ohio Recovery and Deferral Mechanisms [Member] Ohio Recovery and Deferral Mechanisms [Member] Ohio House Bill 95 Ohio House Bill95 [Member] Information on the Ohio House Bill 95. Public Utilities, General Disclosures [Line Items] Public Utilities, General Disclosures [Line Items] Length of project plan required for recovery under new legislation Length of project plan required for recovery under new legislation Length of project plan required for recovery under new legislation Project spend life to date Project spend life to date Project spend life to date Capital expenditures under plan Total Capital Expenditures Under Seven Year Plan Total Capital Expenditures Under Seven Year Plan Operating expenses Regulatory Matters, Operation Expenses Requested For Recovery Regulatory Matters, Operation Expenses Requested For Recovery Capital investments Regulatory Matters, Capital Investments Requested For Recovery Regulatory Matters, Capital Investments Requested For Recovery Recovery period beginning in 2018 Regulatory Matters, Recovery Term Regulatory Matters, Recovery Term Payments for capital improvements Payments for Capital Improvements Bill impact per customer per month Impact on Customer Bill Per Month The limit on the deferrals, represented as a bill impact per customer per month, allowed under VEDO's Capital Expenditure Program filed under Ohio House Bill 95. Increase in base rates and charges Public Utilities, Increase In Base Rates And Charges Public Utilities, Increase In Base Rates And Charges Period to recover costs of capital investments Public Utilities, Period To Recover Costs Of Capital Investments Public Utilities, Period To Recover Costs Reserves Allowance for Doubtful Accounts Receivable, Current Common stock, shares issued (in shares) Common Stock, Shares, Issued Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Customer [Axis] Customer [Axis] Customer [Domain] Customer [Domain] Natural Gas Customers Natural Gas Customers [Member] Natural Gas Customers [Member] Electric Customers Electric Customers [Member] Electric Customers [Member] Indiana Gas Indiana Gas [Member] Refers to an entity under the control of the same parent as another entity (that is, a sister company). VEDO Vectren Energy Delivery of Ohio [Member] Vectren Energy Delivery of Ohio [Member] CenterPoint Energy, Inc. [Member] Pacer Merger Sub [Member] Pacer Merger Sub [Member] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Vectren Corp And CenterPoint Energy, Inc. Merger CenterPoint Energy and Pacer Merger Sub, Inc. Merger Agreement [Member] Vectren Corp And CenterPoint Energy, Inc. Merger Agreement [Member] Public utilities subsidiaries owned by wholly owned subsidiary 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. Approximate number of customers Approximate Number Of Customers Pertains to the approximate number customers serviced by the Company. Number of primary business areas Number Of Primary Business Areas Number Of Primary Business Areas Business merger, cash received per share (in dollars per share) Business Acquisition, Cash Received Per Share Business Acquisition, Cash Received Per Share Business merger, termination fees Business Acquisition, Required Termination Fees Business Acquisition, Required Termination Fees Environmental Matters Disclosure [Abstract] Environmental & Sustainability Matters Environmental Loss Contingency Disclosure [Text Block] Electric Modernization Program - SB 560 Electric Modernization Program - SB 560 [Member] Electric Modernization Program - SB 560 [Member] Renewable Generation - SB 29 Renewable Generation - SB 29 [Member] Renewable Generation Project - SB 29 [Member] SIGECO Electric Environmental Compliance Filing SIGECO Electric Environmental Compliance Filing [Member] SIGECO Electric Environmental Compliance Filing [Member] Electric Demand Side Management Program Electric Demand Side Management Filing [Member] Electric Demand Side Management Filing [Member] Electric Generation and Compliance Electric Generation and Compliance [Member] Electric Generation and Compliance [Member] Investment under plan Investment In Plan Investment In Plan Requested recovery in rates of investments Public Utilities, Requested Recovery in Rates of Investments Public Utilities, Requested Recovery in Rates of Investments Regulatory assets Regulatory Assets Number of solar projects filed for authority to recover costs Number Of Solar Projects With Authority To Recover Costs Number Of Solar Projects With Authority To Recover Costs Additional solar generation resulting from project Public Utilities, Electric Power, Additional Solar Generation Resulting From Project Public Utilities, Electric Power, Additional Solar Generation Resulting From Project Additional battery storage resources resulting from project Public Utilities, Electric Power, Additional Battery Storage Resources Resulting From Project Public Utilities, Electric Power, Additional Battery Storage Resources Resulting From Project Estimated cost of project Estimated Capital Expenditures Under Project Plan Estimated Capital Expenditures Under Project Plan Amount of capital investments to date in equipment for mercury control Amount of capital investments to date in equipment for mercury control Amount of capital investments to date in equipment for coal fired generation units to control mercury emissions in air and water. Amount of capital investments to date in equipment to control sulfur trioxide emissions Amount of capital investments to date in equipment to control sulfur trioxide emissions Amount of capital investments to date in equipment to control sulfur trioxide emissions. Estimated cost of equipment to comply with MATS Estimated cost of equipment to comply with MATS Estimated cost of equipment to comply with MATS Estimated cost of equipment required by the NOV Estimated cost of equipment required by the NOV Estimated cost of equipment required by the NOV SIGECO Electric Demand Side Management Program Filing [Abstract] Vectren South Electric Demand Side Management Program Filing [Abstract] Vectren South Electric Demand Side Management Program Filing [Abstract] Maximum period for recovery under energy efficiency program Maximum period for recovery under energy efficiency program Maximum period for recovery under energy efficiency program Estimated Average Measure Life Of Lost Margin Recovery Plan Estimated Average Measure Life Of Lost Margin Recovery Plan Estimated Average Measure Life Of Lost Margin Recovery Plan Electric utility revenue FERC Return On Equity Complaints [Abstract] FERC Return On Equity Complaint [Abstract] FERC Return On Equity Complaint [Abstract] Current return on equity used in MISO transmission owners rates Current return on equity used in MISO transmission owners rates Current return on equity percentage used in MISO transmission owners rates, which includes SIGECO's formula transition rates. Reduced return on equity percentage sought by third party through joint complaint Reduced return on equity percentage sought by third party through joint complaint Reduced return on equity percentage sought by third party under joint complaint filed with the FERC under Section 206 of the Federal Power Act against MISO and various MISO transmission owners, including SIGECO. FERC authorized base ROE percentage for first refund period FERC authorized base ROE percentage for first refund period FERC authorized base ROE percentage FERC authorized base ROE percentage for second refund period FERC authorized base ROE percentage for second refund period FERC authorized base ROE percentage for second refund period FERC authorized incentive ROE percentage for first refund period FERC Authorized Incentive ROE Percentage for First Refund Period FERC Authorized Incentive ROE Percentage for First Refund Period Gross investment in qualifying projects Gross Investment In Qualifying Transmission Projects Gross investment in qualifying electric transmission projects constructed by the Company in its service territory that meet certain MISO criteria. Net plant balance for qualifying projects Net Investment in Qualifying Transmission Projects Net investment in qualifying electric transmission projects constructed by the Company in its service territory that meet certain MISO criteria. Gas combined cycle generating facility Public Utilities, Gas Combined Cycle Generating Facility Public Utilities, Gas Combined Cycle Generating Facility Gas combined cycle generating facility, cost Public Utilities, Gas Combined Cycle Generating Facility, Cost Public Utilities, Gas Combined Cycle Generating Facility, Cost Requested recovery of environmental investments Public Utilities, Requested Recovery Of Environmental Investments Public Utilities, Requested Recovery Of Environmental Investments Universal solar energy Public Utilities, Universal Solar Energy Public Utilities, Universal Solar Energy Commitments & Contingencies Commitments and Contingencies Disclosure [Text Block] Supplemental Cash Flow Information Cash Flow, Supplemental Disclosures [Text Block] Electric Rate & Regulatory Matters Public Utilities, General Disclosures - Electric [Text Block] Public Utilities, General Disclosures - Electric [Text Block] Site Contingency [Table] Site Contingency [Table] Environmental Remediation Contingency [Axis] Environmental Remediation Contingency [Axis] Environmental Remediation Contingency [Domain] Environmental Remediation Contingency [Domain] Ash Ponds Ash Ponds [Member] Ash Ponds [Member] Environmental Remediation Site [Axis] Environmental Remediation Site [Axis] Environmental Remediation by Entity [Domain] Environmental Remediation Site [Domain] Site Contingency [Line Items] Site Contingency [Line Items] Number of coal fired units Number Of Coal Fired Units Number Of Coal Fired Units Additional capacity from new plant Public Utilities, Natural Gas Combined Cycle Plant Public Utilities, Natural Gas Combined Cycle Plant New renewable generation power Public Utilities, New Renewable Generation Public Utilities, New Renewable Generation Reduction of carbon emissions Reduction Of Carbon Emissions Reduction Of Carbon Emissions Emission rate after installation of new technology Emission Rate After Installation Of New Technology Emission Rate After Installation Of New Technology Grid modernization costs Public Utilities, Grid Modernization Costs Grid Modernization Costs Coal Ash Waste Disposal, Ash Ponds and Water [Abstract] Coal Ash Waste Disposal, Ash Ponds and Water [Abstract] Estimated capital expenditures to comply with Ash Pond and Coal Ash disposal regulations Ash Pond and Coal Ash Disposal Exit Costs, Anticipated Cost Total anticipated costs associated with remediation, site restoration, postclosure, monitoring commitments, or other exit costs that may occur on the sale, disposal, or abandonment of a particular property. Ash Pond and Coal Ash Disposal Exit Costs Revised Anticipated Cost Ash Pond and Coal Ash Disposal Exit Costs Revised Anticipated Cost Revised anticipated costs associated with remediation, site restoration, postclosure, monitoring commitments, or other exit costs that may occur on the sale, disposal, or abandonment of a particular property. Asset retirement obligation (ARO) Asset Retirement Obligation Estimated spend for ash pond dam reinforcement and other operational changes Estimated spend for ash pond dam reinforcement and other operational changes Estimated spend for ash pond dam reinforcement and other operational changes Notification period of issuance of the renewal of its intent to retire a unit Notification Period Of Issuance Of Renewal To Retire Unit Notification Period Of Issuance Of Renewal To Retire Unit Estimated capital expenditures to comply with Clean Water Act Estimated capital expenditures to comply with Clean Water Act Estimated capital expenditures related to Clean Water Act granted that new infrastructure is required. Air Quality [Abstract] Air Quality [Abstract] -- None. No documentation exists for this element. -- 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. Climate Changes [Abstract] Climate Changes [Abstract] Reduction of carbon dioxide emissions Reduction Of Carbon Dioxide Emissions Reduction Of Carbon Dioxide Emissions Manufactured Gas Plants Environmental Remediation Obligations [Abstract] 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 Cumulative costs recorded Environmental Remediation Expense Insurance coverage, amount received Insurance Recoveries Total estimated insurance recoveries Total Estimated Insurance Recoveries Total amount expected to be recovered under the terms of the insurance contracts. Accrued costs included in Other Liabilities Accrual for Environmental Loss Contingencies Number of qualified defined benefit pension plans Number Of Defined Benefit Pension Plans Number Of Defined Benefit Pension Plans Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Employer contribution to qualified pension plans Defined Benefit Plan, Plan Assets, Contributions by Employer