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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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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.

+ References

No definition available.

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- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3255-108585

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- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3291-108585

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SHORT-TERM AND LONG-TERM DEBT - Summary of Long-Term Debt Issuance and Repayments (Details) - USD ($) $ in Thousands	1 Months Ended					6 Months Ended
	Jul. 31, 2022	Jun. 30, 2022	May 31, 2022	Mar. 31, 2022	Feb. 28, 2022	Jun. 30, 2022	Jun. 30, 2021
Debt Instrument [Line Items]
Retirement of Long-Term Debt						$ (770,000)	$ (1,022,000)
NSTAR Electric
Debt Instrument [Line Items]
Retirement of Long-Term Debt						$ 0	$ (250,000)
NSTAR Electric \| Debentures \| 4.55% 2022 Debentures
Debt Instrument [Line Items]
Interest rate, stated percentage			4.55%
Issuances			$ 450,000
NSTAR Electric \| First Mortgage \| NSTAR Gas 4.40% Series V First Mortgage Bonds \| Subsequent Event
Debt Instrument [Line Items]
Interest rate, stated percentage	4.40%
Yankee Gas \| First Mortgage \| Yankee Gas 8.48% Series B First Mortgage Bonds
Debt Instrument [Line Items]
Interest rate, stated percentage				8.48%
Retirement of Long-Term Debt				$ (20,000)
EGMA \| First Mortgage \| EGMA 4.70% Series C First Mortgage Bonds
Debt Instrument [Line Items]
Interest rate, stated percentage		4.70%				4.70%
Issuances		$ 100,000
NSTAR Gas \| First Mortgage \| NSTAR Gas 4.40% Series V First Mortgage Bonds \| Subsequent Event
Debt Instrument [Line Items]
Issuances	$ 125,000
Eversource Parent \| Senior Notes \| Eversource Parent 2.90% Series V Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage					2.90%
Issuances					$ 650,000
Eversource Parent \| Senior Notes \| Eversource Parent 3.38% Series W Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage					3.38%
Issuances					$ 650,000
Eversource Parent \| Senior Notes \| Eversource Parent 4.20% Series X Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage		4.20%				4.20%
Issuances		$ 900,000
Eversource Parent \| Senior Notes \| Eversource Parent 4.60% Series Y Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage		4.60%				4.60%
Issuances		$ 600,000
Eversource Parent \| Senior Notes \| Eversource Parent 2.75% Series K Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage				2.75%
Retirement of Long-Term Debt				$ (750,000)