Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Trading Arrangement: Trading Arrangement [Axis] Indiana Crossroads Solar Indiana Crossroads Solar [Member] Indiana Crossroads Solar Maximum Maximum [Member] Short-term Debt, Type [Axis] Short-Term Debt, Type [Axis] Title of 12(b) Security Title of 12(b) Security Number of Agreements Number of Agreements Number of Agreements Subsequent Event Subsequent Event [Member] Schedule of Available-for-sale Securities [Table] Debt Securities, Available-for-Sale [Table] Net Income Available to Common Shareholders - Diluted Net Income (Loss) Available to Common Stockholders, Diluted Maturities of Senior Debt Maturities of Senior Debt Debt, Weighted Average Interest Rate Debt, Weighted Average Interest Rate Derivative Instruments, Gain (Loss) [Table] Derivative Instruments, Gain (Loss) [Table] Adjustment to Compensation, Amount Adjustment to Compensation Amount Cash From Financing Activities Related To The Change In Short-Term Borrowings Due To The Securitization Transactions Cash From Financing Activities Related To The Change In Short-Term Borrowings Due To The Securitization Transactions Cash from financing activities related to the change in short-term borrowings due to the securitization transactions Schedule of Available-for-sale Securities, Major Types of Debt and Equity Securities Financial Instrument [Axis] Segment Reporting [Abstract] Segment Reporting [Abstract] Noncancelable Commitments - e-storage Noncancelable Commitments - e-storage Noncancelable Commitments - e-storage Accrued compensation and employee benefits Employee-related Liabilities, Current Changes to Liability for Uncertain Tax Positions Changes to Liability for Uncertain Tax Positions Changes to Liability for Uncertain Tax Positions Nature of Expense [Axis] Nature of Expense [Axis] Pension And Other Postretirement Benefits Retirement Benefits [Text Block] Guarantor Obligations, Maximum Exposure, Undiscounted Guarantor Obligations, Maximum Exposure, Undiscounted Increase (Decrease) in Effective Tax Rate Increase (Decrease) in Effective Tax Rate Increase (Decrease) in Effective Tax Rate Derivative Instrument Derivative Instrument [Axis] U.S. Treasury debt securities US Treasury and Government [Member] Financial Instruments, Owned, US Government and Agency Obligations, at Fair Value Financial Instruments, Owned, US Government and Agency Obligations, at Fair Value Investments by Consolidated and Nonconsolidated Entities [Axis] Consolidated Entities [Axis] Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Emergency Order 202c Emergency Order 202c [Member] Emergency Order 202c Other comprehensive (loss) income: Other Comprehensive Income (Loss), Net of Tax [Abstract] Investments by Consolidated and Nonconsolidated Entities [Domain] Consolidated Entities [Domain] Distribution to NIPSCO minority interest holders Payments to Noncontrolling Interests Payments to Noncontrolling Interests Long-term incentive plan Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs, Net Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs, Net Electric production fuel, at average cost Energy Related Inventory, Coal Common Stock, Par or Stated Value Per Share Common Stock, Par or Stated Value Per Share Equity Units Stock Issued During the Period, Equity Units Value Stock Issued During the Period, Equity Units Value Other Liabilities Liabilities, Noncurrent [Abstract] Equity Units Components [Axis] Equity Units Components [Axis] Equity Units Components Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Total Capitalization Capitalization, Long-Term Debt and Equity Asset Retirement Obligation Asset Retirement Obligation Primary business segments Number of Reportable Segments Adjustments for New Accounting Pronouncements [Axis] Accounting Standards Update [Axis] Total Current Liabilities Current liabilities Liabilities, Current Other taxes Taxes, Miscellaneous Taxes, Miscellaneous Dilutive potential common shares Dilutive potential common shares: [Abstract] Dilutive potential common shares: Short-term Debt, Type [Domain] Short-Term Debt, Type [Domain] Comprehensive Income: Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Entity Address, City or Town Entity Address, City or Town Document Document [Domain] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Capital Unit, Class [Domain] Capital Unit, Class [Domain] Significant Other Observable Inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Total other comprehensive (loss) income Net current-period other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Variable Interest Entities [Abstract] Variable Interest Entities Forward Contract Indexed to Issuer's Equity, Shares Forward Contract Indexed to Issuer's Equity, Shares Subsequent Event Type Subsequent Event Type [Axis] Schedule of Variable Interest Entities [Table] Schedule of VIE Assets and Liabilities [Table] Schedule of VIE Assets and Liabilities Net unrealized gain (loss) on cash flow hedges Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax Schedule of Long-term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Schedule Of Operating Income Derived From Revenues And Expenses By Segment Segment Reporting [Table Text Block] Related and Nonrelated Parties [Axis] Related and Nonrelated Parties [Axis] Other comprehensive income (loss), net of tax Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax Proceeds from Debt, Net of Issuance Costs Proceeds from Debt, Net of Issuance Costs Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Document Period End Date Document Period End Date Preferred Stock, Shares Outstanding Beginning balance Ending balance Preferred Stock, Shares Outstanding Earnings Per Share Earnings Per Share, Basic [Abstract] Net Assets Net Assets Customer deposits and credits Pension and Other Postretirement Non Service Cost Pension and Other Postretirement Non Service Cost Business Combination, Transaction Cost, Excluding Separately Recognized Transaction Business Combination, Transaction Cost, Excluding Separately Recognized Transaction Contributions from NIPSCO and GenCo minority interest holders Proceeds from Noncontrolling Interests Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, Tax OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, Tax Supplemental Disclosures of Cash Flow Information Cash Flow, Supplemental Disclosures [Text Block] Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Entity Shell Company Entity Shell Company Redeemable Noncontrolling Interest, Equity, Other, Carrying Amount Redeemable Noncontrolling Interest, Equity, Other, Carrying Amount Consolidation Items [Domain] Consolidation Items [Domain] Accounts Receivable, Allowance for Credit Loss Accounts Receivable, Allowance for Credit Loss [Table Text Block] Earnings Per Share Earnings Per Share [Text Block] Earnings Per Share [Abstract] Earnings Per Share [Abstract] Document Fiscal Period Focus Document Fiscal Period Focus Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Total Liabilities Liabilities Trading Symbol Trading Symbol Partner Type [Axis] Partner Type [Axis] Capital expenditures Payments to Acquire Property, Plant, and Equipment Capacity Purchase Commitments 2028 through 2040 Market Capacity Purchase Commitments 2028 through 2040 Market Capacity Purchase Commitments Increase Decrease In Exchange Gas Receivable Payable Increase Decrease In Exchange Gas Receivable Payable Increase or decrease in exchange gas receivable payable. Company Selected Measure Name Company Selected Measure Name Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Residential Residential [Member] Residential Equity Units purchase contract payment balance Incremental Common Shares Attributable to Dilutive Effect of Equity Unit purchase contract payment balance Incremental Common Shares Attributable to Dilutive Effect of Equity Unit Purchase Contract Payment Balance - If-Converted Long-Term Purchase Commitment, Amount Long-Term Purchase Commitment, Amount Equity Securities, FV-NI, Cost Equity Securities, FV-NI, Cost Increase (Decrease) in Other Accrued Liabilities Increase (Decrease) in Other Accrued Liabilities NiSource Electric Generation and Power Delivery NiSource Electric Generation and Power Delivery [Member] NiSource Electric Generation and Power Delivery Operating Activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Dividends Payable, Current Dividends Payable, Current Public Utility [Axis] Public Utility [Axis] Junior Notes Junior Notes [Member] Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] Distributions to tax equity partners Distributions to Tax Equity Partners Distributions to Tax Equity Partners Deferred income taxes and investment tax credits Deferred Income Taxes and Tax Credits US Treasury Securities US Treasury Securities [Member] Goodwill [Text Block] Goodwill [Text Block] Components of working capital(1) Increase (Decrease) in Other Operating Assets and Liabilities, Net Equity costs, premiums and other debt related costs Payment of Financing and Stock Issuance Costs Award Timing Predetermined Award Timing Predetermined [Flag] Net Property, Plant and Equipment Public Utilities, Property, Plant and Equipment, Net Public Utilities, Property, Plant and Equipment, Net Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Fair Value, Inputs, Level 1 Fair Value, Inputs, Level 1 [Member] Effective income tax rates Effective Income Tax Rate Reconciliation, Percent Product Liability Contingency, Third-Party Recovery, Percentage Product Liability Contingency, Third-Party Recovery, Percentage Forward Oct 25 Forward Oct 25 [Member] Forward Oct 25 Shares restricted under stock plans Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements Inventory, Current [Table] Inventory, Current [Table] Regulated Operations [Abstract] Regulated Operations [Abstract] Preferred Stock, Par or Stated Value Per Share Preferred Stock, Par or Stated Value Per Share Long-term debt (including current portion), Estimated Fair Value Long-Term Debt, Fair Value Depreciation Depreciation Other Ownership Interests, Name [Domain] Other Ownership Interests, Name [Domain] Scenario, Unspecified Scenario [Domain] Partner Type of Partners' Capital Account, Name [Domain] Partner Type of Partners' Capital Account, Name [Domain] Variable Interest Entity Primary Beneficiary Member GenCo Variable Interest Entity Primary Beneficiary Member GenCo [Member] Variable Interest Entity Primary Beneficiary Member GenCo Service Area By County Service Area By County Service Area By County Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract] Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax Current portion of long-term debt Long-Term Debt and Lease Obligation, Current Revolving credit facility interest rate of 2.13% at March 31, 2020 Long-term Line of Credit Long-Term Line of Credit Change in Accounting Principle, Accounting Standards Update, Adopted [true false] Change in Accounting Principle, Accounting Standards Update, Adopted [true false] Dividends paid - common stock Payments of Ordinary Dividends, Common Stock Expiration Date Trading Arrangement Expiration Date Change in cash, cash equivalents and restricted cash Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Excluding Exchange Rate Effect, Including Discontinued Operation Postemployment Benefits [Abstract] Postemployment Benefits [Abstract] Hedging Relationship [Axis] Hedging Relationship [Axis] Gas in Storage [Abstract] Gas in Storage [Abstract] Gas in Storage [Abstract] Restricted Cash Restricted Cash and Cash Equivalent Total Stockholders’ Equity Beginning balance Ending balance Equity, Including Portion Attributable to Noncontrolling Interest Nonrelated Party Nonrelated Party [Member] Preferred Stock, Per Share Amounts of Preferred Dividends in Arrears Preferred Stock, Per Share Amounts of Preferred Dividends in Arrears Dividends: Dividends [Abstract] Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Derivative [Table] Derivative [Table] NIPSCO Holdings II NIPSCO Holdings II [Member] NIPSCO Holdings II Issuance of common stock, net of issuance costs Proceeds from Issuance of Common Stock Common Stock, No Par Value Common Stock, No Par Value Investing Activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] Nameplate Capacity Nameplate Capacity Nameplate Capacity Estimated Maximum Disgorgement Exposure Estimated Maximum Disgorgement Exposure Estimated Maximum Disgorgement Exposure Unaffiliated Unaffiliated [Member] Unaffiliated [Member] Industrial Industrial [Member] Industrial [Member] Segments [Domain] Segments [Domain] Customer Accounts Receivable, Billed (Less Reserve) Customer Accounts Receivable, Billed (Less Reserve) Customer Accounts Receivable, Billed (Less Reserve) Other Ownership Interests Name [Axis] Other Ownership Interests Name [Axis] Scenario [Axis] Scenario [Axis] Contractual Obligation Contractual Obligation Accrued insurance liabilities Accrued Insurance, Noncurrent Payment to renewable generation asset developer Payment to renewable generation asset developer Payment to renewable generation asset developer Payment to renewable generation asset developer PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Debt Instrument, Interest Rate, Stated Percentage Debt Instrument, Interest Rate, Stated Percentage Common stock Dividends, Common Stock, Cash Total NiSource Stockholders’ Equity Shares outstanding Equity, Attributable to Parent Accounting Standards Update 2020-06 Accounting Standards Update 2020-06 [Member] Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement ASSETS Assets [Abstract] Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost Insider Trading Policies and Procedures [Line Items] Recently Adopted Accounting Pronouncements [Line Items] Recently Adopted Accounting Pronouncements [Line Items] Recently Adopted Accounting Pronouncements [Line Items] Allowance for credit losses Accounts Receivable, Allowance for Credit Loss, Current Seasonal Limit Seasonal Limit Transfers Accounted For As Secured Borrowings Seasonal Limit Regulatory assets Regulatory Asset, Current Operating Revenues Gross Profit [Abstract] Advance deposits transferred to capital expenditures Advance deposits transferred to capital expenditures Advance deposits transferred to capital expenditures Accounts receivable Interest Income (Expense), Nonoperating Accrued liability for postretirement and postemployment benefits Liability, Pension and Other Postretirement and Postemployment Benefits, Noncurrent Goodwill Goodwill [Table Text Block] Entity Central Index Key Entity Central Index Key Additional paid-in capital Additional Paid in Capital, Common Stock Schedule of Guarantor Obligations [Table] Guarantor Obligation [Table] Equity [Abstract] Equity [Abstract] Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] us-gaap_VariableInterestEntityPrimaryBeneficiaryMemberGenCo us-gaap_VariableInterestEntityPrimaryBeneficiaryMemberGenCo [Member] us-gaap_VariableInterestEntityPrimaryBeneficiaryMemberGenCo Preferred Stock Redemption Premium Preferred Stock Redemption Premium Preferred Stock Redemption Premium Payments for asset retirement obligations Asset Retirement Obligation, Cash Paid to Settle Other Comprehensive Income (Loss) before reclassifications Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Substantial Completion Substantial Completion [Member] Substantial Completion Ownership [Axis] Ownership [Axis] Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), before Tax Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), before Tax Fair Value, Assets Measured on Recurring Basis, Disclosure Items [Axis] Fair Value Hierarchy and NAV [Axis] Preferred stock Dividends, Preferred Stock, Cash Expected return on assets Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-Term Rate of Return on Plan Assets Commodity Price Risk Programs Commodity Price Risk Programs [Member] Commodity Price Risk Programs [Member] Debt and Equity Securities, Unrealized Gain (Loss) Debt and Equity Securities, Unrealized Gain (Loss) Finance Lease, Liability, Payment, Due Finance Lease, Liability, to be Paid Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] All Individuals All Individuals [Member] Regulatory Liability [Domain] Regulatory Liability [Domain] Commercial Commercial [Member] Commercial [Member] Statement [Line Items] Statement [Line Items] Rosewater Rosewater [Member] Rosewater Total Assets Total Assets Assets Equity Units Stock Issued During the Period, Shares, Equity Units Stock Issued During the Period, Shares, Equity Units Debt Instrument, Increase, Accrued Interest Line of Credit Facility, Increase, Accrued Interest Schedule of Defined Benefit Plans Disclosures [Table] Defined Benefit Plan [Table] New Accounting Pronouncements and Changes in Accounting Principles [Abstract] Accounting Standards Update and Change in Accounting Principle [Abstract] Operating Segments Operating Segments [Member] Interest expense, net Interest Expense, Nonoperating Gross Unrealized Gains Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax PEO PEO [Member] Dividends payable - common stock Common Dividends Payable, Current Carrying value as of the balance sheet date of dividends declared but unpaid on equity securities issued by the entity and outstanding. Used to reflect the current portion of the liabilities (due within one year). ATM forward sale agreements Incremental Common Shares Attributable to Dilutive Effect of Equity Forward Agreements Other noncurrent liabilities Finance lease obligations Other Liabilities, Noncurrent Goodwill Goodwill Goodwill Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Change Due to Subsequent Interim Measurement, Weighted-Average Expected Long-Term Rate of Return on Plan Assets Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Change Due to Subsequent Interim Measurement, Weighted-Average Expected Long-Term Rate of Return on Plan Assets Retirement Plan Type [Axis] Retirement Plan Type [Axis] Loss on impairment of assets Impairment And Gain Loss On Sale Of Assets, Net Impairment and gain loss on sale of assets net. Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Preferred Stock, Redemption Amount Preferred Stock, Redemption Amount Preferred stock redemption Preferred stock redemption Retained Deficit Retained Earnings [Member] Revolving Credit Facility Revolving Credit Facility [Member] Public Authority Public Authority [Member] Public Authority Common Stock, Shares, Outstanding Beginning balance Ending balance Common Stock, Shares, Outstanding Award Timing Disclosures [Line Items] Carrying Amount And Estimated Fair Values Of Financial Instruments Fair Value, by Balance Sheet Grouping [Table Text Block] Corporate/Other debt securities Corporate Debt Securities [Member] Diluted Earnings Per Share Earnings Per Share, Diluted Preferred stock - par value, 20,000,000 shares authorized; 0 and 0 shares outstanding, respectively Preferred Stock, Value, Outstanding Sections 205, 202 (c), and 309 Emergency order Cost Recovery Sections 205, 202 (c), and 309 Emergency order Cost Recovery Sections 205, 202 (c), and 309 Emergency order Cost Recovery Ownership [Domain] Ownership [Domain] Forward May 26 Forward May 26 [Member] Forward May 26 Natural Gas Natural Gas [Member] NiSource Gas Distribution NiSource Gas Distribution [Member] NiSource Gas Distribution Customer revenues Revenue from Contract with Customer, Excluding Assessed Tax Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Miscellaneous Non-Operating Income (Expense) Miscellaneous Non-Operating Income (Expense) Miscellaneous Non-Operating Income (Expense) Subsegments [Domain] Subsegments [Domain] Short-term debt due to asset securitization Transfers Accounted for as Secured Borrowings, Associated Liabilities, Carrying Amount NIPSCO Electric Generation NIPSCO Electric Generation [Member] NIPSCO Electric Generation Accounts Receivable Program Accounts Receivable Program [Member] Accounts receivable program. Other Income (Deductions) Other Nonoperating Income (Expense) [Abstract] Operating Income Operating Income (Loss) Consolidated Operating Income (Loss) Operating Income (Loss) Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Service Cost Defined Benefit Plan, Service Cost NIPSCO Operations NIPSCO Operations [Member] NIPSCO Operations Equity Securities Equity Securities [Member] Wind Power Purchase Agreement, Purchase Percentage Wind Power Purchase Agreement, Purchase Percentage Wind Power Purchase Agreement, Purchase Percentage Beginning balance Ending balance Common Stock, Shares, Issued Common Stock, Shares, Issued Total Operating Revenues Total Operating Revenues Regulated Operating Revenue Regulated Operating Revenue Second TCA Debt Interest Rate Reset Debt Interest Rate Rest Debt Interest Rate Deposits to renewable generation asset developer Deposits to renewable generation asset developer Deposits to renewable generation asset developer Long-term Debt, Current and Noncurrent [Abstract] Long-Term Debt, Current and Noncurrent [Abstract] Allowance for Credit Loss Allowance for Credit Loss Debt Securities, Available-for-Sale, Allowance for Credit Loss Accumulated Other Comprehensive Loss Comprehensive Income (Loss) Note [Text Block] Cost of energy Cost of Goods and Service, Excluding Depreciation, Depletion, and Amortization Product and Service [Domain] Product and Service [Domain] Class of Stock [Line Items] Class of Stock [Line Items] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Capitalization Capitalization, Long-Term Debt and Equity [Abstract] Other Ownership Interest Other Ownership Interest [Member] Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Series B-1 Preferred Stock Series B-1 Preferred Stock [Member] Series B-1 Preferred Stock [Member] Deferred income taxes Deferred Income Tax Liabilities, Net Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Termination Date Trading Arrangement Termination Date Purchase Contract Liability Purchase Contract Liability [Member] Purchase Contract Liability Subsequent Events [Abstract] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Fair Value, Recurring and Nonrecurring [Table] Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Shares To Be Issued Under Stock Purchase Contracts Shares To Be Issued Under Stock Purchase Contracts Shares To Be Issued Under Stock Purchase Contracts Customer Accounts Receivable, Unbilled (Less Reserve) Customer Accounts Receivable, Unbilled (Less Reserve) Customer Accounts Receivable, Unbilled (Less Reserve) Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Unrecognized pension and OPEB benefit (costs) Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax Denominator Denominator [Abstract] Denominator Other accruals Other Liabilities, Current Fair Value as of Grant Date Award Grant Date Fair Value Operating Activities [Axis] Operating Activities [Axis] Schedule of Goodwill [Table] Goodwill [Table] Forward Contract Indexed to Issuer's Equity, Forward Rate Per Share Forward Contract Indexed to Issuer's Equity, Forward Rate Per Share Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Operating Costs and Expenses Operating Costs and Expenses Arrangement Duration Trading Arrangement Duration NIPSCO NIPSCO [Member] NIPSCO Consolidation Items [Axis] Consolidation Items [Axis] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Entity Registrant Name Entity Registrant Name Regulatory Deferral - Joint Venture Regulatory Deferral - Joint Venture Regulatory Deferral - Joint Venture Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Revenues Revenues Revenues NIPSCO Holdings NIPSCO Holdings [Member] NIPSCO Holdings Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Series B and B-1 Preferred stock redemption premium Preferred Stock Redemption Premiums Preferred Stock Redemption Premiums Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] All Award Types Award Type [Domain] Fair Value Fair Value Disclosures [Text Block] Significant Unobservable Inputs (Level 3) Fair Value, Inputs, Level 3 [Member] Subsidiary, Ownership Percentage, Noncontrolling Owner Subsidiary, Ownership Percentage, Noncontrolling Owner Document Information, Document [Axis] Document Information, Document [Axis] Contract with Customer, Liability Contract with Customer, Liability Schedule of Short-term Debt [Table] Short-Term Debt [Table] Other Assets Other Assets Legal Entity [Axis] Legal Entity [Axis] Available-for-sale debt securities (amortized cost of $164.6 and $145.8, respectively) Available-for-sale, securities Debt Securities, Available-for-Sale, Noncurrent Joint Ventures Joint Ventures [Member] Joint Ventures Forward February 26 Forward February 26 [Member] Forward February 26 Cash, cash equivalents and restricted cash at beginning of period Cash, Cash Equivalents and Restricted Cash at End of Period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Non-NEOs Non-NEOs [Member] Miscellaneous Misc. [Member] Misc. [Member] Accounts Receivable, Sale Accounts Receivable, Sale Customer [Domain] Customer [Domain] Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Customer deposits and credits Contract with Customer, Liability, Current Statistical Measurement [Axis] Statistical Measurement [Axis] Derivative Instruments, Gain (Loss) Derivative Instruments, Gain (Loss) [Table Text Block] Award Type Award Type [Axis] Deferred Derivative Gain (Loss) Deferred Derivative Gain (Loss) [Member] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Retained deficit Retained Earnings (Accumulated Deficit) Product and Service [Axis] Product and Service [Axis] Equity Securities, FV-NI Equity Securities, FV-NI Number of waste disposal sites identified by program Number of waste disposal sites identified by program Number of waste disposal sites identified by program. Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Short-term Debt [Line Items] Short-Term Debt [Line Items] Pension Plan Pension Plan [Member] Common Stock Common Stock [Member] Fair Value Debt Securities, Available-for-Sale Series B Preferred Stock [Member] Series B Preferred Stock [Member] Derivative Contract Derivative Contract [Domain] Forward Contract Indexed to Issuer's Equity, Settlement Alternatives, Shares, at Fair Value Forward Contract Indexed to Equity, Settlement, Cash, Amount Public Utilities General Disclosures [Table] Public Utilities General Disclosures [Table] Type of Adoption [Domain] Accounting Standards Update [Domain] Debt Securities, Available-for-Sale, Realized Gain (Loss) Debt Securities, Available-for-Sale, Realized Gain (Loss) Total Capitalization and Liabilities Liabilities and Equity Employee Stock Option Share-Based Payment Arrangement, Option [Member] Noncontrolling interest in consolidated subsidiaries Equity, Attributable to Noncontrolling Interest Segments Statement, Business Segments Segments [Axis] Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Related and Nonrelated Parties [Domain] Related and Nonrelated Parties [Domain] Equity Units purchase contracts Incremental Common Shares Attributable to Dilutive Effect of Equity Unit Purchase Agreements If-Converted Incremental Common Shares Attributable to Dilutive Effect of Equity Unit Purchase Agreements If-Converted CCR Remediation CCR Remediation [Member] CCR Remediation Tabular List, Table Tabular List [Table Text Block] Accounting Standards Update 2020-04 [Member] Name Awards Close in Time to MNPI Disclosures, Individual Name Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] Other Assets Assets, Noncurrent [Abstract] Materials and supplies, at average cost Inventory, Raw Materials and Supplies, Gross Off-system Off-system [Member] Off-system [Member] Adjustment to Compensation: Adjustment to Compensation [Axis] Amounts reclassified from accumulated other comprehensive income (loss) Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Inventory [Line Items] Inventory [Line Items] Total Assets, Fair Value Disclosure Long-term debt, excluding amounts due within one year Long-Term Debt and Lease Obligation Forward February 22 Forward February 27 [Member] Forward February 27 Forward May 22 Forward May 22 [Member] Forward May 22 Name Measure Name Pay vs Performance Disclosure [Line Items] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] 401(k) and profit sharing Stock Issued During Period, Shares, Employee Benefit Plan Debt Instrument [Line Items] Debt Instrument [Line Items] Corporate and Other Corporate Segment and Other Operating Segment [Member] Additional Paid-in Capital Additional Paid-in Capital [Member] Income before Income Taxes Income (Loss) from Continuing Operations before Income Taxes, Domestic Investment Company, Committed Capital Investment Company, Committed Capital Name Trading Arrangement, Individual Name Cash and cash equivalents Cash and Cash Equivalent Cash and Cash Equivalent Public Utilities, Requested Rate Increase (Decrease), Percentage Public Utilities, Requested Rate Increase (Decrease), Percentage Company Selected Measure Amount Company Selected Measure Amount Customer annual demand Customer annual demand Customer annual demand Short-Term Borrowings Short-Term Debt [Text Block] Income Taxes Receivable Income Taxes Receivable Depreciation and amortization Depreciation, Depletion and Amortization Depreciation, Depletion and Amortization Guarantor Obligations, Origin and Purpose Guarantor Obligations, Origin and Purpose Long-term incentive plan Shares Issued, Shares, Share-Based Payment Arrangement, after Forfeiture Preferred Stock, Redemption Amount Preferred Stock, Redemption Amount Non-PEO NEO Non-PEO NEO [Member] Depreciation, Nonproduction Depreciation, Nonproduction Other, Net Other Income and Other Expense Disclosure [Text Block] Increase (Decrease) in Other Regulatory Assets Increase (Decrease) in Other Regulatory Assets Investments and Other Assets Regulated Entity, Other Assets, Noncurrent [Abstract] Award Timing Method Award Timing Method [Text Block] Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Recognized actuarial loss Defined Benefit Plan, Amortization of Gain (Loss) Net Income Attributable to NiSource Net Income (Loss) Attributable to Parent Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Balance Sheet Location [Axis] Location, Statement of Financial Position, Balance [Axis] Restatement Determination Date: Restatement Determination Date [Axis] Components Of Accumulated Other Comprehensive Loss Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Generation Holdings II Generation Holdings II [Member] Generation Holdings II Gas storage Energy Related Inventory, Natural Gas in Storage Customer Advances and Deposits Proceeds from Deposits from Customers Interest Rate Risk Interest Rate Risk [Member] Issued: Stock Issued During Period Shares [Abstract] Stock issued during period shares. Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Add: Dilutive effect of Equity Units Dilutive Securities, Effect on Basic Earnings Per Share, Dilutive Convertible Securities Statistical Measurement [Domain] Statistical Measurement [Domain] Accumulated depreciation and amortization Public Utilities, Property, Plant and Equipment, Accumulated Depreciation Document Fiscal Year Focus Document Fiscal Year Focus Short-term Debt, Status [Domain] Short-term Debt, Status [Domain] [Domain] for Short-term Debt, Status [Axis] Customer [Axis] Customer [Axis] Increase Decrease In Prepayments And Other Current Assets Increase Decrease In Prepayments And Other Current Assets Increase decrease in prepayments and other current assets. Common stock - $0.01 par value,750,000,000 shares authorized; 479,498,053 and 478,432,058 shares outstanding, respectively Common Stock, Value, Issued Commodity Contract Length Commodity Contract Length Commodity Contract Length Public Utilities, General Disclosures [Line Items] Public Utilities, General Disclosures [Line Items] Short-term Debt, Status [Axis] Short-term Debt, Status [Axis] Short-term Debt, Status [Axis] Restatement Determination Date Restatement Determination Date Unconsolidated affiliates Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Defined Benefit Plan, Expected Return (Loss) on Plan Assets Expected return on assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Fair Value Disclosure [Line Items] Fair Value Disclosure [Line Items] Fair Value Disclosure [Line Items] NIPSCO minority interest holders NIPSCO minority interest holders [Member] NIPSCO minority interest holders Payments to Acquire Assets, Investing Activities Payments to Acquire Assets, Investing Activities Undistributed Earnings (Loss) Allocated to Participating Securities, Basic Participating Securities, Distributed and Undistributed Earnings (Loss), Basic Accounts Receivable, Allowance for Credit Loss Accounts Receivable, Allowance for Credit Loss Regulatory liabilities Regulatory Liability, Noncurrent Regulatory Liability, Noncurrent Amendment Flag Amendment Flag Goodwill [Line Items] Goodwill [Line Items] Current Liabilities Liabilities, Current [Abstract] Debt and Equity Securities, FV-NI [Line Items] Debt and Equity Securities, FV-NI [Line Items] Current period provisions Accounts Receivable, Credit Loss Expense (Reversal) Repayments of finance lease obligations Finance Lease, Principal Payments Series A Corporate Units Series A Corporate Units [Member] Series A Corporate Units Forward September 27 Forward September 27 [Member] Forward September 27 Proceeds from Contributed Capital Proceeds from Contributed Capital Gross Unrealized Losses Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax Standby Letters of Credit Standby Letters of Credit [Member] Forward February 23 Forward February 23 [Member] Forward February 23 Debt Securities, Available-for-sale Debt Securities, Available-for-Sale [Table Text Block] Loss on sale of assets Gain (Loss) on Disposition of Other Assets Investments [Domain] Investments [Domain] Total Other Liabilities Other Liabilities Liabilities, Noncurrent Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Entity Address, State or Province Entity Address, State or Province Regulatory Matters Public Utilities Disclosure [Text Block] Series C Preferred Stock Series C Preferred Stock [Member] PEO Total Compensation Amount PEO Total Compensation Amount Assets Assets, Fair Value Disclosure [Abstract] Basic Average Common Shares Outstanding Weighted Average Number of Shares Outstanding, Basic Regulatory assets Regulatory Assets, Noncurrent Regulatory Asset, Noncurrent Total Investments and Other Assets Investments and Other Noncurrent Assets Regulatory Liability [Axis] Regulatory Liability [Axis] Schedule of Cash Flow, Supplemental Disclosures Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Commercial paper outstanding Commercial Paper Document Information [Line Items] Document Information [Line Items] Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Class of Stock [Axis] Class of Stock [Axis] Income Tax Examination, Penalties Expense Income Tax Examination, Penalties Expense Columbia Of Massachusetts Columbia Of Massachusetts [Member] Columbia Of Massachusetts [Member] Derivative, Nonmonetary Notional Amount Derivative, Nonmonetary Notional Amount Net Income Available to Common Shareholders Net Income Available to Common Shareholders Net Income (Loss) Available to Common Stockholders, Basic Investor Ownership Investor Ownership [Member] Investor Ownership Forward June 12 Forward June 12 [Member] Forward June 12 Line of Credit Facility, Maximum Borrowing Capacity Line of Credit Facility, Maximum Borrowing Capacity Accounting Standards Update 2021-01 Accounting Standards Update 2021-01 [Member] Treasury stock Treasury Stock, Value New Accounting Pronouncements, Policy New Accounting Pronouncements, Policy [Policy Text Block] Capital expenditures included in current liabilities Capital Expenditures Incurred but Not yet Paid Noncontrolling Interest Noncontrolling Interest [Member] Unsecured Debt Unsecured Debt [Member] Noncontrolling Interest Disclosure Noncontrolling Interest Disclosure [Text Block] Long-Term Debt Long-Term Debt Short-term Debt [Abstract] Short-Term Debt [Abstract] Stock Issuances: Stock Issued During Period Value [Abstract] Stock issued during period value. Changes in Assets and Liabilities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract] Shawn Anderson [Member] Shawn Anderson Net Cash Flows used for Investing Activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Liability for Estimated Remediation Costs Liability for Estimated Remediation Costs Liability for Estimated Remediation Costs Regulatory Assets Regulatory Asset Equity Equity [Text Block] Security Exchange Name Security Exchange Name Numerator Numerator [Abstract] Numerator Business Combination, Price of Acquisition, Expected Business Combination, Price of Acquisition, Expected Earning Per Share [Table] Earning Per Share [Table] Earning Per Share Interest accrued Interest Payable, Current Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Name Outstanding Recovery, Individual Name Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Recently Adopted Accounting Pronouncements [Table] Recently Adopted Accounting Pronouncements [Table] Recently Adopted Accounting Pronouncements [Table] Accrual for Environmental Loss Contingencies, Period Increase (Decrease) Accrual for Environmental Loss Contingencies, Period Increase (Decrease) Equity Units Equity Units [Member] Equity Units Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Net unrealized loss on available-for-sale securities OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment and Tax Other investments Other Long-Term Investments Payments to Acquire Interest in Subsidiaries and Affiliates Payments to Acquire Interest in Subsidiaries and Affiliates Subsidiary, Ownership Percentage, Parent Subsidiary, Ownership Percentage, Parent Pension and OPEB Items Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Long-term Debt (including current portion), Carrying Amount Long-Term Debt, Gross Equity Units Components [Domain] Equity Units Components [Domain] Equity Units Components [Domain] Equity Units Stock Purchase Contract Liability Payments Equity Units Stock Purchase Contract Liability Payments Equity Units Stock Purchase Contract Liability Payments Securitization Transaction Fees Securitization Transaction Fees Securitization transaction fees Shares, Issued Shares, Issued Compensation Amount Outstanding Recovery Compensation Amount Individual: Individual [Axis] Diluted Average Common Shares Diluted Average Common Shares Weighted Average Number of Shares Outstanding, Diluted Accounts Receivable Allowance For Credit Loss [Line Items] Accounts Receivable Allowance For Credit Loss [Line Items] Accounts Receivable Allowance For Credit Loss [Line Items] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Entity Emerging Growth Company Entity Emerging Growth Company Underlying Security Market Price Change Underlying Security Market Price Change, Percent Commercial Paper Commercial Paper [Member] Risk Management Activities Derivative Instruments and Hedging Activities Disclosure [Text Block] Cost of removal Payments for Removal Costs Regulatory Asset [Axis] Regulatory Asset [Axis] Short-term borrowings Short-term Debt Short-Term Debt Schedule of Series A Equity Units [Table] Schedule of Series A Equity Units [Table] Schedule of Series A Equity Units [Table] Defined Benefit Plan, Plan Assets, Contributions by Employer Employer contributions Defined Benefit Plan, Plan Assets, Contributions by Employer Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Discount rate Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Treasury Stock, Common Treasury Stock, Common [Member] Intangible Asset, Goodwill and Other [Abstract] Intangible Asset, Goodwill and Other [Abstract] Fair Value Disclosure [Line Items] Debt Securities, Available-for-Sale [Line Items] Repayments of Unsecured Debt Repayments of Unsecured Debt Stock Redeemed or Called During Period, Shares Stock Redeemed or Called During Period, Shares Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Net Income Available to Common Shareholders - Basic Excluding Participating Securities Net Income Available to Common Shareholders - Basic Excluding Participating Securities Net Income Available to Common Shareholders - Basic Excluding Participating Securities Equity tax partner Equity tax partner [Member] Equity tax partner All Executive Categories All Executive Categories [Member] Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Components Of The Plans' Net Periodic Benefits Cost Schedule of Net Benefit Costs [Table Text Block] Accounting Changes and Error Corrections [Abstract] Increase (Decrease) in Income Taxes Receivable Increase (Decrease) in Income Taxes Receivable Schedule of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] 401(k) and profit sharing Stock Issued During Period, Value, Employee Benefit Plan Business Segment Information Segment Reporting [Text Block] ATM program Stock Issued During Period, Value, Other Minimum Minimum [Member] Second Term Credit Agreement Second Term Credit Agreement Second Term Credit Agreement Investment Type [Axis] Investment Type [Axis] Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Variable Interest Entities Variable Interest Entity Disclosure [Text Block] Deferred charges and other noncurrent assets Increase Decrease In Deferred Charges And Other Non Current Assets Increase decrease in deferred charges and other non current assets. Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Wholesale Wholesale [Member] Wholesale Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table [Member] Total Financial Liabilities Fair Value Disclosure Public Utilities, Requested Rate Increase (Decrease), Amount Public Utilities, Requested Rate Increase (Decrease), Amount Total Net Periodic Benefits Cost Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Long-term incentive plan Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs Common Stock, Shares Authorized Common Stock, Shares Authorized Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Debt Securities, Available-for-Sale, Realized Gain Debt Securities, Available-for-Sale, Realized Gain Exercise Price Award Exercise Price Segment Reporting [Line Items] Segment Reporting [Line Items] Document Quarterly Report Document Quarterly Report Deferred charges and other Deferred charges and other Deferred charges and other Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] Accounting Standards Update Accounting Standards Update [Extensible Enumeration] Operating Activities [Domain] Operating Activities [Domain] Preferred Stock, Liquidation Preference Per Share Preferred Stock, Liquidation Preference Per Share Regulatory Assets and Liabilities Disclosure [Abstract] Regulatory Assets and Liabilities Disclosure [Abstract] Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Equity Method Investments Equity Method Investments Equity Component [Domain] Equity Component [Domain] Other Commitments And Contingencies [Line Items] Other Commitments And Contingencies [Line Items] Other Commitments And Contingencies [Line Items] Common Stock Aggregate Sale Price Common Stock Aggregate Sale Price Common Stock Aggregate Sale Price Accounts receivable Accounts Receivable, before Allowance for Credit Loss, Current Adoption Date Trading Arrangement Adoption Date Schedule of Other Nonoperating Income (Expense) Schedule of Other Nonoperating Income (Expense) [Table Text Block] Total Other Deductions, Net Nonoperating Income (Expense) Increase (Decrease) in Accrued Taxes Payable Increase (Decrease) in Accrued Taxes Payable NiSource NiSource [Member] NiSource [Member] Title Trading Arrangement, Individual Title Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Increase Decrease In Other Accruals Increase Decrease In Other Accruals Increase decrease in other accruals. Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Columbia Operations Columbia Operations [Member] Columbia Operations [Member] Contributions from noncontrolling interests Distributions to noncontrolling interests Noncontrolling Interest, Increase from Subsidiary Equity Issuance Customer Refund Liability, Current Customer Refund Liability, Current Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] MGP Sites Mgp Sites [Member] All Adjustments to Compensation All Adjustments to Compensation [Member] Corporate and Other Segment Reporting, Reconciling Item, Corporate Nonsegment [Member] Other adjustments Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Other Item Preferred Stock, Liquidation Preference, Value Preferred Stock, Liquidation Preference, Value Net Cash Flows from Operating Activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Termination Loans Termination Loans Stockholders' Equity Equity, Attributable to Parent [Abstract] Income Statement [Abstract] Income Statement [Abstract] Employee stock purchase plan Stock Issued During Period, Shares, Employee Stock Purchase Plans Document Transition Report Document Transition Report Operating Expenses Operating Expenses [Abstract] Accounts Receivable, Allowance for Credit Loss Accounts Receivable Allowance For Credit Loss [Table] Accounts Receivable Allowance For Credit Loss Eliminations Intersegment Eliminations [Member] Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] City Area Code City Area Code Allowance for Credit Loss [Abstract] Document Information [Table] Document Information [Table] Subsequent Event Subsequent Events [Text Block] Name Forgone Recovery, Individual Name Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Electric Operations Electric Operations [Member] Electric Operations. Contract with Customer, Contract Asset, Contract Liability, and Receivable [Abstract] Contract with Customer, Contract Asset, Contract Liability, and Receivable [Abstract] Entity [Domain] Entity [Domain] Recorded reserves to cover environmental remediation at various sites Accrual for Environmental Loss Contingencies Preferred Stock, Shares Issued Preferred Stock, Shares Issued Employee Benefits and Share-Based Compensation Employee Benefits and Share-Based Compensation Amortization of prior service credit Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Gas Distribution NIPSCO Gas Distribution [Member] NIPSCO Gas Distribution Preferred dividends redemption premium reversal Preferred dividends redemption premium reversal Preferred dividends redemption premium reversal Employee stock purchase plan Stock Issued During Period, Value, Employee Stock Purchase Plan Reasonably possible remediation costs variance from reserve Reasonably possible remediation costs variance from reserve Dividends payable - preferred stock Preferred Dividends Payable, Current Carrying value as of the balance sheet date of preferred dividends declared but unpaid on preferred equity securities issued by the entity and outstanding. Used to reflect the current portion of the liabilities (due within one year). Dunns Bridge I Dunns Bridge I [Member] Dunns Bridge I Available-for-sale Securities, Maturities, Next Twelve Months, Fair Value Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Subsequent Event Type [Domain] Subsequent Event Type [Domain] Schedule of Series A Equity Units [Line Items] Schedule of Series A Equity Units [Line Items] Schedule of Series A Equity Units [Line Items] Taxes accrued Taxes Payable, Current Series A Preferred Stock Series A Preferred Stock [Member] Gains and Losses on Securities AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Parent [Member] Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Accumulated Other Comprehensive Loss [Table] Accumulated Other Comprehensive Income (Loss) [Table] Entity Current Reporting Status Entity Current Reporting Status Net Cash Flows from Financing Activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Interim Period, Costs Not Allocable [Domain] Interim Period, Costs Not Allocable [Domain] Total Shareholder Return Amount Total Shareholder Return Amount Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, Tax Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, Tax Liabilities Liabilities, Fair Value Disclosure [Abstract] Risk management assets Cash Flow Hedging [Member] Net change in commercial paper and other short-term borrowings Proceeds from (Repayments of) Short-Term Debt, Maturing in Three Months or Less Other, Net [Abstract] Other, Net [Abstract] Other, Net [Abstract] Operation and maintenance Utilities Operating Expense, Maintenance and Operations Utilities Operating Expense, Maintenance and Operations Adjustments to Reconcile Net Income to Net Cash from Operating Activities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] Write-offs charged against allowance Write-offs charged against allowance Accounts Receivable, Allowance for Credit Loss, Writeoff Loss Contingencies by Nature of Contingency [Axis] Loss Contingency Nature [Axis] Property, Plant, and Equipment, after Accumulated Depreciation, Depletion, and Amortization Property, Plant, and Equipment, after Accumulated Depreciation, Depletion, and Amortization Financing Activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Interest cost Defined Benefit Plan, Interest Cost Other revenues Regulated Operating Revenue, Other Shares Issued, Price Per Share Shares Issued, Price Per Share Defined Benefit Plan, Assumed Health Care Cost Trend Rate, Description Defined Benefit Plan, Assumed Health Care Cost Trend Rate, Description Financial Instruments Financial Instruments [Domain] Other Comprehensive Income (Loss), Tax [Abstract] Other Comprehensive Income (Loss), Tax [Abstract] Risk management assets Derivative Asset LIFO Inventory Amount LIFO Inventory Amount Gas in Storage Inventory Disclosure [Text Block] Underlying Securities Award Underlying Securities Amount Revenue from Contract with Customer Revenue from Contract with Customer [Text Block] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Prepaid Expense, Current Prepaid Expense, Current Columbia Of Ohio Columbia Of Ohio [Member] Columbia of Ohio. Subsegments [Axis] Subsegments [Axis] Preferred Stock Preferred Stock [Member] Other investing activities Payment for (Proceeds from) Other Investing Activity Contributions from NIPSCO and GenCo minority interest holders Proceeds from (Payments to) Noncontrolling Interests Segment Reporting [Table] Segment Reporting [Table] Prepayments and other Other Assets, Current Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] All Trading Arrangements All Trading Arrangements [Member] Other Performance Measure, Amount Other Performance Measure, Amount Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, Tax Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, Tax Current Fiscal Year End Date Current Fiscal Year End Date Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Derivative [Line Items] Derivative [Line Items] Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Common Stock, Dividends, Per Share, Declared Common Stock, Dividends, Per Share, Declared Entity File Number Entity File Number Long-term incentive plan Shares Issued, Value, Share-Based Payment Arrangement, after Forfeiture Cash Flow Hedge, Interest Rate, Hedging Exposure, Maximum Period Cash Flow Hedge, Interest Rate, Hedging Exposure, Maximum Period Gas storage and other inventories Allowance for Funds Used During Construction, Capitalized Interest Distributions to noncontrolling interests Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Customer Accounts Receivable Customer Accounts Receivable [Table Text Block] Tabular disclosure of customer accounts receivable [Table Text Block] Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Senior Notes Senior Notes Preferred Stock, Dividends Per Share, Declared Dividends Declared Per Share Preferred Stock, Dividends Per Share, Declared Measure: Measure [Axis] Variable Interest Entities Assets and Liabilities Schedule of Variable Interest Entities [Table Text Block] Beginning balance Ending balance Treasury Stock, Common, Shares Asset retirement obligations Asset retirement obligations Asset Retirement Obligations, Noncurrent AOCI Tax, Attributable to Parent AOCI Tax, Attributable to Parent Accounting Standards Update 2021-01 Retrospective Accounting Standards Update 2021-01 Retrospective [Member] Exchange gas payable Exchange gas payable Exchange gas payable Equity Components Equity Components [Axis] Shares contingently issuable under employee stock plans Incremental Common Shares Attributable to Dilutive Effect of Contingently Issuable Shares Related Party Related Party [Member] Preferred Stock Shares Redeemed Preferred Stock Shares Redeemed Preferred Stock Shares Redeemed Preferred Stock Shares Redeemed Limit of GCA Volumes Limit of GCA Volumes Limit of GCA Volumes Regulatory assets/liabilities Increase (Decrease) in Regulatory Assets and Liabilities Entity Interactive Data Current Entity Interactive Data Current Net income (loss) attributable to noncontrolling interest Net Income (Loss) Attributable to Noncontrolling Interest Available-for-sale Securities Available-for-Sale Securities [Member] Entity Small Business Entity Small Business Plant Public Utilities, Property, Plant and Equipment, Plant in Service Forward March 03 Forward March 03 [Member] Forward March 03 Utility Plant [Domain] Utility Plant [Domain] MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Derivative Asset, Subject to Master Netting Arrangement, after Offset Derivative Asset, Subject to Master Netting Arrangement, after Offset Total Other Assets Other Assets, Noncurrent Other Assets, Noncurrent Document Type Document Type Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Advanced deposits Payments For Advanced Deposits for Project Costs Payments For Advanced Deposits for Project Costs Subsequent Event [Line Items] Subsequent Event [Line Items] Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Debt Securities, Trading, and Equity Securities, FV-NI [Table] Debt Securities, Trading, and Equity Securities, FV-NI [Table] Proceeds from issuance of long-term debt Proceeds from Issuance of Long-Term Debt Local Phone Number Local Phone Number Guaranty Liabilities Guaranty Liabilities Other Postretirement Benefit Plan Other Postretirement Benefits Plan [Member] Consolidated Variable Interest Entities Consolidated Variable Interest Entities [Member] Consolidated Variable Interest Entities Increase (Decrease) in Finished Goods and Work in Process Inventories Increase (Decrease) in Finished Goods and Work in Process Inventories Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Executive Category: Executive Category [Axis] Earnings Per Share [Line Items] Earnings Per Share [Line Items] Earnings Per Share CAPITALIZATION AND LIABILITIES Liabilities and Equity [Abstract] Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Gas Distribution Operations Gas Distribution Operations [Member] Gas Distribution Operations [Member] Schedule of Variable Interest Entities [Table] Variable Interest Entity [Table] Series A Corporate Units Series A Corporate Units Series A Corporate Units Transfers between Fair Value Hierarchies Transfers between Fair Value Hierarchies Transfers between Fair Value Hierarchies PEO Name PEO Name Gains and Losses on Cash Flow Hedges Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] Segment Reporting, Other Segment Item, Amount Segment Reporting, Other Segment Item, Amount Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Entity Tax Identification Number Entity Tax Identification Number Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Remeasurement due to Settlement Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Remeasurement due to Settlement Increase (Decrease) in Accounts Payable Increase (Decrease) in Accounts Payable Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Exchange gas receivable Exchange gas receivable Exchange gas receivable. Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Comprehensive Income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Subsequent Event [Table] Subsequent Event [Table] Schedule of Derivative Instruments in Statement of Financial Position, Fair Value Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Basic Earnings Per Share Earnings Per Share, Basic Total Current Assets Current assets Assets, Current Insider Trading Arrangements [Line Items] Accounts receivable, net Accounts Receivable, after Allowance for Credit Loss, Current Obligations to renewable generation asset developer Obligations to renewable generation asset developer Obligations to renewable generation asset developer Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Capital Units by Class [Axis] Capital Units by Class [Axis] Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] 2028 through 2030 market capacity purchase commitments 2028 through 2030 market capacity purchase commitments 2028 through 2030 market capacity purchase commitments Cover [Abstract] Cover [Abstract] Intersegment Intersegment [Member] Intersegment [Member] ATM Program Equity Remaining Available for Issuance ATM Program Equity Remaining Available for Issuance ATM Program Equity Remaining Available for Issuance Short-term Debt, Weighted Average Interest Rate, at Point in Time Short-Term Debt, Weighted Average Interest Rate, at Point in Time Mechanical Completion Mechanical Completion [Member] Mechanical Completion Equity Awards Adjustments Equity Awards Adjustments [Member] Hedging Relationship [Domain] Hedging Relationship [Domain] Regulatory Asset [Domain] Regulatory Asset [Domain] Other noncurrent liabilities and deferred credits and charges Increase (Decrease) in Other Noncurrent Liabilities Other, net Other, net Other Nonoperating Income (Expense) Forward June 26 Forward June 26 [Member] Forward June 26 Long-term Debt Long-Term Debt [Text Block] Undivided Beneficial Ownership Interest, Percent Undivided Beneficial Ownership Interest, Percent Undivided Beneficial Ownership Interest, Percent Preferred Stock, Shares Authorized Preferred Stock, Shares Authorized Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Regulatory Liabilities Regulatory Liability Class of Stock [Domain] Class of Stock [Domain] Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Property, Plant and Equipment Public Utilities, Property, Plant and Equipment [Abstract] Other Commitment Other Commitment Schedule of Stock by Class - Preferred Schedule of Stock by Class [Table Text Block] Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Accounts Payable Accounts Payable Income Taxes Income Tax Disclosure [Text Block] Accounts payable Accounts Payable, Current Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Retirement Plan Type [Domain] Retirement Plan Type [Domain] Entity Filer Category Entity Filer Category Debt Securities, Available-for-sale, Unrealized Loss Position Debt Securities, Available-for-Sale, Unrealized Loss Position Supplemental Cash Flow Elements [Abstract] Basis of Accounting Presentation Basis of Accounting [Text Block] At The Market Program At The Market Program [Member] At The Market Program [Member] Schedule of Stock by Class - Preferred Stock, Class of Stock [Table] Net Income Net Income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Current Assets Assets, Current [Abstract] Risk management liabilities Derivative Liability Senior Notes Senior Notes [Member] Contributions/Distributions to/from Noncontrolling Interest Contributions/Distributions to/from Noncontrolling Interest [Table Text Block] Contributions received from and distributions made to noncontrolling interest holders. Entity Address, Address Line One Entity Address, Address Line One Defined Benefit Plan, Ultimate Health Care Cost Trend Rate Defined Benefit Plan, Ultimate Health Care Cost Trend Rate Income Taxes Income Tax Expense (Benefit) Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Treasury Stock, Preferred Treasury Stock, Preferred [Member] Variable Interest Entity, Primary Beneficiary Variable Interest Entity, Primary Beneficiary [Member] Recent Accounting Pronouncements Accounting Standards Update and Change in Accounting Principle [Text Block] Statement [Table] Statement [Table] Regulatory liabilities Regulatory Liability, Current Indiana Crossroads Wind Indiana Crossroads Wind [Member] Indiana Crossroads Wind Recoveries of amounts previously written off Accounts Receivable, Allowance for Credit Loss, Recovery Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments and Hedging Activities Disclosure [Abstract]