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

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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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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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 01, 2019	Feb. 01, 2019	Jul. 31, 2019	Jun. 30, 2019	Apr. 30, 2019	Jun. 30, 2019	Jun. 30, 2018	Feb. 01, 2009
Debt Instrument [Line Items]
Repayments						$ (250,437)	$ (860,421)
CL&P
Debt Instrument [Line Items]
Repayments						(250,000)	(300,000)
CL&P \| Senior Notes \| 4.00% 2018 Series A First Mortgage Bonds
Debt Instrument [Line Items]
Issuances					$ 300,000
Interest rate, stated percentage					4.00%
CL&P \| Senior Notes \| 4.00% 2018 Series A First Mortgage Bonds \| Eversource Parent
Debt Instrument [Line Items]
Long-term debt				$ 800,000		800,000
CL&P \| Senior Notes \| 5.50% 2009 Series A First Mortgage Bonds
Debt Instrument [Line Items]
Repayments		$ (250,000)
Interest rate, stated percentage								5.50%
NSTAR Electric \| Senior Notes \| 3.25% 2019 Debentures
Debt Instrument [Line Items]
Issuances	$ 400,000
Interest rate, stated percentage	3.25%
PSNH
Debt Instrument [Line Items]
Repayments						$ 0	$ (110,000)
PSNH \| Senior Notes \| 3.60% 2019 Series T First Mortgage Bonds
Debt Instrument [Line Items]
Issuances				$ 300,000
Interest rate, stated percentage				3.60%		3.60%
Other \| Senior Notes \| NSTAR Gas 3.74% Series Q First Mortgage Bonds \| Subsequent Event
Debt Instrument [Line Items]
Issuances			$ 75,000
Interest rate, stated percentage			3.74%