RATE REDUCTION BONDS AND VARIABLE INTEREST ENTITIES - Summary of the Impact of Funding on the Income Statements (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Condensed Income Statements, Captions [Line Items]
Interest Expense on RRB Principal (included in Interest Expense)	$ 300,600	$ 222,300	$ 822,600	$ 624,100
PSNH
Condensed Income Statements, Captions [Line Items]
Amortization of RRB Principal (included in Amortization of Regulatory Assets/(Liabilities), Net)	(51,881)	9,963	(101,874)	35,234
PSNH | VIE | Rate Reduction Bonds
Condensed Income Statements, Captions [Line Items]
Amortization of RRB Principal (included in Amortization of Regulatory Assets/(Liabilities), Net)	10,800	10,800	32,400	32,400
Interest Expense on RRB Principal (included in Interest Expense)	$ 3,500	$ 3,900	$ 10,800	$ 11,900