RATE REDUCTION BONDS AND VARIABLE INTEREST ENTITIES - Summary of the Impact of Funding on the Income Statements (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Condensed Income Statements, Captions [Line Items]
Interest Expense on RRB Principal (included in Interest Expense)	$ 207,313	$ 160,090	$ 401,858	$ 313,334
PSNH
Condensed Income Statements, Captions [Line Items]
Amortization of RRB Principal (included in Amortization of Regulatory Assets, Net)	19,954	(9,218)	25,271	(36,052)
Interest Expense on RRB Principal (included in Interest Expense)	19,106	14,757	36,649	28,402
PSNH | VIE | Rate Reduction Bonds
Condensed Income Statements, Captions [Line Items]
Amortization of RRB Principal (included in Amortization of Regulatory Assets, Net)	10,800	10,800	21,600	21,600
Interest Expense on RRB Principal (included in Interest Expense)	$ 3,900	$ 4,300	$ 8,000	$ 8,700