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, 2023	May 31, 2023	Mar. 31, 2023	Jan. 31, 2023	Jun. 30, 2023	Jun. 30, 2022
Debt Instrument [Line Items]
Retirement of Long-Term Debt					$ (853,000)	$ (770,000)
CL&P
Debt Instrument [Line Items]
Retirement of Long-Term Debt					$ (400,000)	$ 0
CL&P | First Mortgage | CL&P 2023 Series A First Mortgage Bonds
Debt Instrument [Line Items]
Interest rate, stated percentage (in percent)				5.25%
Issuances				$ 500,000
CL&P | First Mortgage | CL&P 2023 Series B First Mortgage Bonds | Subsequent Event
Debt Instrument [Line Items]
Interest rate, stated percentage (in percent)	4.90%
Issuances	$ 300,000
CL&P | First Mortgage | CL&P 2013 Series A First Mortgage Bonds
Debt Instrument [Line Items]
Interest rate, stated percentage (in percent)				2.50%
Retirement of Long-Term Debt				$ (400,000)
PSNH | First Mortgage | PSNH Series W First Mortgage Bonds
Debt Instrument [Line Items]
Interest rate, stated percentage (in percent)				5.15%
Issuances				$ 300,000
Eversource Parent | Senior Notes | Eversource Parent Series Z Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage (in percent)		5.45%	5.45%
Issuances		$ 550,000	$ 750,000
Eversource Parent | Senior Notes | Eversource Parent Series F Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage (in percent)		2.80%
Retirement of Long-Term Debt		$ (450,000)
Eversource Parent | Senior Notes | Eversource Parent Series AA Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage (in percent)		4.75%
Issuances		$ 450,000
Eversource Parent | Senior Notes | Eversource Parent Series BB Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage (in percent)		5.125%
Issuances		$ 800,000