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

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-Topic 210
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The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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-Section 45
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The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

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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
	May 31, 2020	Apr. 30, 2020	Mar. 31, 2020	Jan. 31, 2020	Jun. 30, 2020	Jun. 30, 2019
Debt Instrument [Line Items]
Repayments					$ (270,456)	$ (250,437)
Senior Notes \| Eversource Parent 3.45% Series P Senior Notes \| Eversource Parent
Debt Instrument [Line Items]
Issuances				$ 350,000
Interest rate, stated percentage				3.45%
NSTAR Electric
Debt Instrument [Line Items]
Repayments					$ (95,000)	$ 0
NSTAR Electric \| Senior Notes \| 3.95% 2020 Debentures
Debt Instrument [Line Items]
Issuances			$ 400,000
Interest rate, stated percentage					3.95%
NSTAR Electric \| Senior Notes \| 5.10% Series E Senior Notes
Debt Instrument [Line Items]
Repayments			$ (95,000)
Interest rate, stated percentage					5.10%
NSTAR Gas \| Senior Notes \| NSTAR Gas 4.46% Series N First Mortgage Bonds
Debt Instrument [Line Items]
Repayments				$ (125,000)
Interest rate, stated percentage				4.46%
NSTAR Gas \| Senior Notes \| NSTAR Gas 2.33% Series R First Mortgage Bonds
Debt Instrument [Line Items]
Issuances	$ 75,000
Interest rate, stated percentage	2.33%
NSTAR Gas \| Senior Notes \| NSTAR Gas 3.15% Series S First Mortgage Bonds
Debt Instrument [Line Items]
Issuances	$ 115,000
Interest rate, stated percentage	3.15%
Yankee Gas \| Senior Notes \| Yankee Gas 4.87% Series K First Mortgage Bonds
Debt Instrument [Line Items]
Repayments		$ (50,000)
Interest rate, stated percentage		4.87%