capacity available under preferred stock provisions

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Line of Credit Facility, Amount Outstanding During Period

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- Definition

Percentage of Total Capitalization

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Short-term borrowing limit approved by regulatory agency

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Contractual interest rate for funds borrowed, under the debt agreement.

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

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No definition available.

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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.

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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.

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The amount for notes payable (written promise to pay), due to related parties. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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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.

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No definition available.

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SHORT-TERM DEBT - Narrative (Details) - USD ($)	12 Months Ended
SHORT-TERM DEBT - Narrative (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019	Oct. 21, 2020	May 15, 2020	Dec. 18, 2019	Oct. 25, 2019
Revolving Credit Facility
Short-term Debt [Line Items]
Amount of commercial paper program			$ 550,000,000
Line of Credit
Short-term Debt [Line Items]
Amount outstanding during period	$ 0	$ 0
Eversource \| Commercial Paper
Short-term Debt [Line Items]
Amount of commercial paper program	$ 2,000,000,000.00
Eversource \| Line of Credit
Short-term Debt [Line Items]
Debt instrument term	5 years
Amount of commercial paper program	$ 1,450,000,000
The Connecticut Light and Power Company
Short-term Debt [Line Items]
Short-term borrowing limit approved by regulatory agency						$ 600,000,000
Notes payable to related parties	0	63,800,000
The Connecticut Light and Power Company \| Line of Credit
Short-term Debt [Line Items]
Amount of commercial paper program				$ 450,000,000
Borrowings outstanding	0
NSTAR Electric Company
Short-term Debt [Line Items]
Short-term borrowing limit approved by regulatory agency					$ 655,000,000
Notes payable to related parties	21,300,000	30,300,000
NSTAR Electric Company \| Commercial Paper
Short-term Debt [Line Items]
Amount of commercial paper program	$ 650,000,000
NSTAR Electric Company \| Line of Credit
Short-term Debt [Line Items]
Debt instrument term	5 years
Amount of commercial paper program	$ 650,000,000
Public Service Company of New Hampshire
Short-term Debt [Line Items]
Short-term borrowing limit approved by regulatory agency	383,900,000
Notes payable to related parties	$ 46,300,000	$ 27,000,000
Public Service Company of New Hampshire \| Short Term Debt Authorization Calculation
Short-term Debt [Line Items]
Interest rate	10.00%
Short-term debt borrowing calculation approved by regulatory agency	$ 60,000,000
Public Service Company of New Hampshire \| Line of Credit
Short-term Debt [Line Items]
Amount of commercial paper program				$ 300,000,000
Unsecured Debt \| The Connecticut Light and Power Company
Short-term Debt [Line Items]
Period of maturity restricting provisions of debt	10 years
Total capitalization (as a percentage)	10.00%
Capacity available under preferred stock provisions	$ 907,600,000