Amount of Debt Authorized

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- Definition

capacity available under preferred stock provisions

+ References

No definition available.

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- Definition

Line of Credit Facility, Amount Outstanding During Period

+ References

No definition available.

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- Definition

Percentage of Total Capitalization

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No definition available.

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- Definition

Period of Maturity Restricting Provisions of Debt

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No definition available.

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- Definition

Short-term borrowing limit approved by regulatory agency

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No definition available.

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- References

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- Definition

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

+ References

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- Definition

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.

+ References

No definition available.

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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.

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- Definition

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).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition

Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

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- 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

No definition available.

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SHORT-TERM DEBT - Narrative (Details) - USD ($)	12 Months Ended
SHORT-TERM DEBT - Narrative (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Aug. 01, 2018	Jan. 08, 2018	Dec. 08, 2017	Nov. 30, 2017	Nov. 03, 2016
Short-term Debt [Line Items]
Amount of debt authorized			$ 800,000,000
Commercial Paper
Short-term Debt [Line Items]
Amount of commercial paper program	$ 0	$ 201,200,000.0
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	1,450,000,000			$ 201,200,000.0	$ 1,450,000,000.00
Eversource \| Line of Credit
Short-term Debt [Line Items]
Amount of commercial paper program	$ 1,450,000,000.00
Debt instrument term	5 years
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	69,500,000
NSTAR Electric Company
Short-term Debt [Line Items]
Short-term borrowing limit approved by regulatory agency						$ 655,000,000
Amount of debt authorized			$ 200,000,000
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]
Amount of commercial paper program	$ 650,000,000
Debt instrument term	5 years
NPT
Short-term Debt [Line Items]
Amount of debt authorized							$ 800,000,000
Public Service Company Of New Hampshire
Short-term Debt [Line Items]
Short-term borrowing limit approved by regulatory agency	$ 331,000,000
Notes payable to related parties	$ 57,000,000	262,900,000
Public Service Company Of New Hampshire \| Short Term Debt Authorization Calculation
Short-term Debt [Line Items]
Interest rate stated percentage (up to) (as a percentage)	10.00%
Short-term debt borrowing calculation approved by regulatory agency	$ 60,000,000
Aquarion \| Line of Credit
Short-term Debt [Line Items]
Amount of commercial paper program	$ 100,000,000.0
Short-term Debt		$ 76,000,000
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	$ 758,100,000