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, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Condensed Income Statements, Captions [Line Items]
Interest Expense on RRB Principal (included in Interest Expense)	$ 160,090	$ 145,435	$ 313,334	$ 283,201
PSNH
Condensed Income Statements, Captions [Line Items]
Amortization of RRB Principal (included in Amortization of Regulatory Assets, Net)	(9,218)	(26,274)	(36,052)	(44,821)
Interest Expense on RRB Principal (included in Interest Expense)	14,757	13,821	28,402	28,452
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)	$ 4,300	$ 4,600	$ 8,700	$ 9,300