RATE REDUCTION BONDS AND VARIABLE INTEREST ENTITIES - Income Statement (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Condensed Income Statements, Captions [Line Items]
Interest Expense on RRB Principal (included in Interest Expense)	$ 678,274	$ 582,334	$ 538,452
PSNH
Condensed Income Statements, Captions [Line Items]
Amortization of RRB Principal (included in Amortization of Regulatory Assets, Net)	42,867	86,832	52,804
Interest Expense on RRB Principal (included in Interest Expense)	59,548	56,998	58,127
Variable Interest Entity, Primary Beneficiary | PSNH | Rate Reduction Bonds
Condensed Income Statements, Captions [Line Items]
Amortization of RRB Principal (included in Amortization of Regulatory Assets, Net)	43,200	43,200	43,200
Interest Expense on RRB Principal (included in Interest Expense)	$ 17,000	$ 18,400	$ 19,700