Debt Instrument, Extension Term

No definition available.

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- Definition

Period between issuance and maturity of debt instrument, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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+ Details

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt classified as current. Excludes lease obligation.

+ References

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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt classified as noncurrent. Excludes lease obligation.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Sum of the carrying values as of the balance sheet date of the portions of long-term notes payable due within one year or the operating cycle if longer.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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+ Details

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Period Type:	instant

- Definition

The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

+ References

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- Details

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SHORT-TERM AND LONG-TERM DEBT - Narrative (Details) - USD ($)		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2026	Jun. 30, 2025	Jul. 17, 2026	Jul. 15, 2026	Mar. 03, 2026	Dec. 31, 2025
Line of Credit Facility [Line Items]
Long-term debt, current portion	$ 2,502,629,000	$ 2,502,629,000					$ 1,392,948,000
Long-term debt, repaid		1,616,803,000	$ 375,122,000
Long-term debt	26,608,990,000	26,608,990,000					26,872,433,000
Aquarion \| Discontinued Operations, Disposed of by Sale
Line of Credit Facility [Line Items]
Long-term debt, repaid	612,400,000
NSTAR Electric
Line of Credit Facility [Line Items]
Long-term debt, current portion	700,000,000	700,000,000					300,000,000
Long-term debt, repaid		300,000,000	$ 0
Long-term debt	5,641,846,000	5,641,846,000					5,645,638,000
NSTAR Electric \| Line of Credit \| Subsequent Event
Line of Credit Facility [Line Items]
Maximum borrowing capacity				$ 3,200,000,000
CL&P
Line of Credit Facility [Line Items]
Notes payable to Eversource parent	107,000,000	107,000,000					0
Long-term debt, current portion	500,000,000	500,000,000					0
Long-term debt	4,611,306,000	4,611,306,000					5,110,067,000
CL&P \| Related Party
Line of Credit Facility [Line Items]
Notes payable to Eversource parent	107,000,000.0	107,000,000.0
CL&P \| Line of Credit
Line of Credit Facility [Line Items]
Maximum borrowing capacity	375,000,000	375,000,000
Amount outstanding under line of credit	0	0					0
PSNH
Line of Credit Facility [Line Items]
Notes payable to Eversource parent	2,100,000	2,100,000					49,300,000
Long-term debt	2,234,486,000	2,234,486,000					2,031,323,000
PSNH \| Related Party
Line of Credit Facility [Line Items]
Notes payable to Eversource parent	2,100,000	2,100,000					49,300,000
PSNH \| Line of Credit
Line of Credit Facility [Line Items]
Maximum borrowing capacity	250,000,000	250,000,000				$ 200,000,000.0
Amount outstanding under line of credit	0	0					0
Commercial Paper \| NSTAR Electric
Line of Credit Facility [Line Items]
Maximum borrowing capacity	650,000,000	650,000,000
Line of Credit \| NSTAR Electric
Line of Credit Facility [Line Items]
Maximum borrowing capacity	650,000,000	650,000,000
Eversource Parent Commercial Paper Program \| Yankee Gas \| Subsequent Event
Line of Credit Facility [Line Items]
Long-term debt					$ 90,000,000.0
Eversource Parent Commercial Paper Program \| Yankee Gas \| Commercial Paper \| Subsequent Event
Line of Credit Facility [Line Items]
Amount outstanding under line of credit					62,300,000
Eversource Parent Commercial Paper Program \| Eversource Gas Company of Massachusetts \| Commercial Paper \| Subsequent Event
Line of Credit Facility [Line Items]
Amount outstanding under line of credit					$ 39,000,000.0
Eversource Parent Commercial Paper Program \| Commercial Paper
Line of Credit Facility [Line Items]
Maximum borrowing capacity	2,000,000,000.00	2,000,000,000.00
Eversource Parent Commercial Paper Program \| Line of Credit
Line of Credit Facility [Line Items]
Maximum borrowing capacity	2,000,000,000.00	$ 2,000,000,000.00
Debt instrument term (in years)		5 years
Debt instrument, extension term		1 year
NSTAR Electric \| Line of Credit \| NSTAR Electric
Line of Credit Facility [Line Items]
Debt instrument term (in years)		5 years
NSTAR Electric and Eversource \| Line of Credit
Line of Credit Facility [Line Items]
Amount outstanding under line of credit	$ 0	$ 0					$ 0