Statistical Measurement [Domain] Statistical Measurement [Domain] Related Parties and Exempt Party-In-Interest EBP, Related Party and Party-in-Interest Transactions [Text Block] Document Information [Line Items] Document Information [Line Items] Eversource Common Shares Fund EBP, Employer, Common Stock Fund [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Participant Contributions EBP, Participant Contribution, Receivable EBP, Description of Plan and Accounting Change [Abstract] Rollover Contributions EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Rollover Investment Type [Axis] Investment Type [Axis] Other Receivables EBP, Other Receivable Number of shares (in shares) EBP, Investment, Number of Shares Administrative Expenses [Line Items] Administrative Expenses [Line Items] Administrative Expenses [Line Items] Tax Status EBP, Tax Status [Text Block] Employer contribution vesting service period EBP, Employer Contribution Vesting Service Period EBP, Employer Contribution Vesting Service Period EBP, Description of Plan [Line Items] EBP, Description of Plan [Line Items] Interest and Dividend Income EBP, Change in Net Asset Available for Benefit, Increase from Interest and Dividend Income on Investment Concentration of investment at fair value of net assets, percentage EBP, Risk and Uncertainty, Concentration of Investment at Fair Value to Net Assets, Percentage EBP, Schedule of Asset Held for Investment [Table] EBP, Schedule of Asset Held for Investment [Table] Participate loan, after deemed distribution EBP, Asset Held for Investment, Participant Loan, after Deemed Distribution Cash and Cash Equivalents EBP, Cash And Cash Equivalents [Policy Text Block] EBP, Cash And Cash Equivalents Fair Value Measurements EBP, Investment, Fair Value and NAV [Text Block] Assets: EBP, Asset Held for Investment [Abstract] Investment cost EBP, Investment Acquired, Excluding Plan Interest in Master Trust, Cost EBP, Investment, Fair Value and NAV [Table] EBP, Investment, Fair Value and NAV [Table] Allowance for credit loss EBP, Note Receivable from Participant, Allowance for Credit Loss Total Contributions EBP, Change in Net Asset Available for Benefit, Increase from Contribution EBP, Employer Contribution, Tranche One EBP, Employer Contribution, Tranche One [Member] EBP, Employer Contribution, Tranche One EBP, Schedule Of Employer Contribution, Participant Compensation Matched EBP, Schedule Of Employer Contribution, Participant Compensation Matched [Table Text Block] EBP, Schedule Of Employer Contribution, Participant Compensation Matched EBP, Related Party and Party-in-Interest Transactions [Table] EBP, Related Party and Party-in-Interest Transactions [Table] EBP, Risk and Uncertainty [Table] EBP, Risk and Uncertainty [Table] Distributions to Participants EBP, Change in Net Asset Available for Benefit, Decrease from Payment to Participant Employer Contributions  EBP, Employer Contribution, Receivable Participant Contributions EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Excluding Rollover EBP, Debt [Abstract] Net Assets Available for Benefits Net Assets Available for Benefits EBP, Net Asset Available for Benefit ESOP Allocated Eversource Energy Common Shares ESOP Allocated Eversource Energy Common Shares [Member] ESOP Allocated Eversource Energy Common Shares Cash and Cash Equivalents Cash and Cash Equivalents [Member] EBP, Schedule of Asset Held for Investment [Line Items] EBP, Schedule of Asset Held for Investment [Line Items] EBP, Accounting Policy [Line Items] EBP, Accounting Policy [Line Items] Separately Managed Account Separately Managed Account [Member] Separately Managed Account EBP, Employer Contribution, Tranche Two EBP, Employer Contribution, Tranche Two [Member] EBP, Employer Contribution, Tranche Two EBP, Employer Contribution, Tranche Three EBP, Employer Contribution, Tranche Three [Member] EBP, Employer Contribution, Tranche Three EBP, Employer, Common Stock EBP, Employer, Common Stock [Member] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Sum of Age and Service Years as of January 1st EBP, Requisite Service Period EBP, Requisite Service Period EBP, Tax Status [Abstract] Increase in Net Assets EBP, Change in Net Asset Available for Benefit, Increase (Decrease) Cover [Abstract] Maximum Maximum [Member] Employer Contributions EBP, Change in Net Asset Available for Benefit, Increase from Employer Contribution, Cash EBP, Risk and Uncertainty [Line Items] EBP, Risk and Uncertainty [Line Items] Minimum Minimum [Member] Maximum annual compensation to total compensation, percentage EBP, Participant Contribution, Pretax, Maximum Annual Compensation to Total Compensation, Percentage Dividend income investment EBP, Change in Net Asset Available for Benefit, Increase from Dividend Income on Investment EBP, Schedule of Asset Held for Investment [Abstract] Entity [Domain] Entity [Domain] Company Contribution EBP, Employer Contribution, Annual Fixed Rate Contribution, Percentage EBP, Employer Contribution, Annual Fixed Rate Contribution, Percentage Assets held for investment EBP, Asset Held for Investment Investment, Identifier [Axis] Investment, Identifier [Axis] EBP, Investment, Fair Value and NAV [Abstract] Matching percentage EBP, Employer Contribution, Matching Percentage Basic of Accounting EBP, Basis of Accounting [Policy Text Block] EBP, Employer Contribution, Sum of Age and Service Years [Domain] EBP, Employer Contribution, Sum of Age and Service Years [Domain] EBP, Employer Contribution, Sum of Age and Service Years [Domain] EBP, Tax Status [Line Items] EBP, Tax Status [Line Items] EBP, Statement of Change in Net Asset Available for Benefit [Table] EBP, Statement of Change in Net Asset Available for Benefit [Table] EBP, Description of Plan [Table] EBP, Description of Plan [Table] Investments EBP, Investment [Policy Text Block] Investments, at Contract Value:  Investment, at contract value EBP, Investment, Excluding Plan Interest in Master Trust, Contract Value Amendment Flag Amendment Flag Revenue sharing agreement, income EBP, Revenue Sharing Agreement, Income EBP, Revenue Sharing Agreement, Income Administrative Expenses Administrative expenses EBP, Change in Net Asset Available for Benefit, Decrease from Administrative Expense Common Collective Trusts Common Collective Trust [Member] Uncategorized Fair Value Measured at Net Asset Value Per Share [Member] EBP, Investment, Fair Value and NAV EBP, Investment, Fair Value and NAV [Table Text Block] Total Deductions EBP, Change in Net Asset Available for Benefit, Decrease Assets held for investment, contract value EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value EBP, Statement of Change in Net Asset Available for Benefit [Abstract] Registered Investment Companies Registered Investment Companies [Member] Registered Investment Companies Investment selling price EBP, Investment Sold, Excluding Plan Interest in Master Trust, Selling Price EBP, Related Party and Party-in-Interest Transactions [Abstract] Less Than 40 Years Less Than 40 Years [Member] Less than 40 years Administrative Expenses EBP, Administrative Expenses [Text Block] EBP, Administrative Expenses Forfeited nonvested account EBP, Forfeited Nonvested Account EBP, Related Party and Party-in-Interest Transactions [Line Items] EBP, Related Party and Party-in-Interest Transactions [Line Items] Fair Value of Financial Instruments EBP, Fair Value Of Financial Instruments [Policy Text Block] EBP, Fair Value Of Financial Instruments EBP, Employer Contribution [Domain] EBP, Employer Contribution [Domain] EBP, Employer Contribution [Domain] Forfeited nonvested account, decrease from employer contribution EBP, Forfeited Nonvested Account, Decrease from Employer Contribution Other Income EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Other Investment Income (Loss) EBP, Statement of Net Asset Available for Benefit [Abstract] Plan Description EBP, Description of Plan [Text Block] Total Investments EBP, Investment, Contract Value Summary of Significant Accounting Policies EBP, Summary of Accounting Policy [Text Block] Total Additions EBP, Change in Net Asset Available for Benefit, Increase EBP, Statement of Net Asset Available for Benefit [Line Items] EBP, Statement of Net Asset Available for Benefit [Line Items] EBP, Employer Contribution [Axis] EBP, Employer Contribution [Axis] EBP, Employer Contribution Entity Central Index Key Entity Central Index Key Participant loan, interest rate EBP, Asset Held for Investment, Participant Loan, Interest Rate Total Investments, at Fair Value Investment at fair value EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value Legal Entity [Axis] Legal Entity [Axis] Entity tax identification number Entity Tax Identification Number Separately Managed Account EBP, Pooled Separate Account [Member] Administrative Expenses [Table] Administrative Expenses [Table] Administrative Expenses [Table] EBP, Accounting Policy, Accounting Standard Update, and Change in Accounting Principle [Abstract] Plan number EBP, Plan Number Increase (decrease) in revenue credit allocation EBP, Change In Net Asset Available For Benefit, Increase (Decrease) From Other Investment Income (Loss), Revenue Credit EBP, Change In Net Asset Available For Benefit, Increase (Decrease) From Other Investment Income (Loss), Revenue Credit Participant receipt deferral age EBP, Participant Receipt Deferral Age EBP, Participant Receipt Deferral Age Document Type Document Type EBP, Statement of Net Asset Available for Benefit [Table] EBP, Statement of Net Asset Available for Benefit [Table] 40 Through 59 Years 40 Through 59 Years [Member] 40 Through 59 Years EBP, Investment, Fair Value and NAV [Line Items] EBP, Investment, Fair Value and NAV [Line Items] Plan Estimates EBP, Use of Estimate [Policy Text Block] 60 Years And Greater 60 Years And Greater [Member] 60 Years And Greater Statistical Measurement [Axis] Statistical Measurement [Axis] Deductions: EBP, Change in Net Asset Available for Benefit, Decrease [Abstract] Involuntary cash-out limit EBP, Involuntary Cash-out Limit EBP, Involuntary Cash-out Limit Notes Receivable from Participants EBP, Note Receivable from Participant Level 2 Fair Value, Inputs, Level 2 [Member] EBP, Schedule of Asset Held for Investment EBP, Schedule of Asset Held for Investment [Table Text Block] Additions: EBP, Change in Net Asset Available for Benefit, Increase [Abstract] Revenue sharing agreement, expense EBP, Revenue Sharing Agreement, Expense EBP, Revenue Sharing Agreement, Expense Net Appreciation in the Fair Value of Investments EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Gain (Loss) on Investment EBP, Accounting Policy [Table] EBP, Accounting Policy [Table] Investments [Domain] Investments [Domain] EBP 005 EBP 005 [Member] EBP 005 Document Information [Table] Document Information [Table] EBP, Statement of Change in Net Asset Available for Benefit [Line Items] EBP, Statement of Change in Net Asset Available for Benefit [Line Items] EBP, Employer Contribution, Sum of Age and Service Years [Axis] EBP, Employer Contribution, Sum of Age and Service Years [Axis] EBP, Employer Contribution, Sum of Age and Service Years EBP, Risk and Uncertainty [Abstract] Level 1 Fair Value, Inputs, Level 1 [Member] Entity Registrant Name Entity Registrant Name Note receivable, interest income EBP, Note Receivable from Participant, Account, Interest Income, Amount EBP, Note Receivable from Participant, Account, Interest Income, Amount EBP, Tax Status [Table] EBP, Tax Status [Table] Investments Held by Brokerage Link Investments Held by Brokerage Link [Member] Investments Held by Brokerage Link EBP, Receivable [Abstract] EBP, Receivable [Abstract] Total Receivables EBP, Receivable Company Contribution EBP, Employer Contribution, Participant Compensation Matched, Percentage Risks and Uncertainties EBP, Risk and Uncertainty [Text Block]