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, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Condensed Income Statements, Captions [Line Items]
Interest Expense on RRB Principal (included in Interest Expense)	$ 178,174	$ 147,962	$ 491,509	$ 431,162
PSNH
Condensed Income Statements, Captions [Line Items]
Amortization of RRB Principal (included in Amortization of Regulatory Assets, Net)	(7,398)	(17,922)	(43,449)	(62,744)
Interest Expense on RRB Principal (included in Interest Expense)	15,030	14,321	43,432	42,774
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	32,400	32,400
Interest Expense on RRB Principal (included in Interest Expense)	$ 4,200	$ 4,500	$ 12,900	$ 13,900