SHORT-TERM DEBT - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 03, 2021
Commercial Paper | Eversource
Short-term Debt [Line Items]
Maximum borrowing capacity	$ 2,000,000,000
Line of Credit
Short-term Debt [Line Items]
Amount outstanding during period	0	$ 0
Line of Credit | Eversource
Short-term Debt [Line Items]
Maximum borrowing capacity	$ 2,000,000,000
Debt instrument term (in years)	5 years
CL&P
Short-term Debt [Line Items]
Short-term borrowing limit approved by regulatory agency			$ 600,000,000
CL&P | Unsecured Debt
Short-term Debt [Line Items]
Period of maturity restricting provisions of debt	10 years
Total capitalization (as a percentage)	10.00%
Capacity available under preferred stock provisions	$ 1,010,000,000.00
CL&P | Line of Credit
Short-term Debt [Line Items]
Maximum borrowing capacity	450,000,000
Borrowings outstanding	0
NSTAR Electric
Short-term Debt [Line Items]
Short-term borrowing limit approved by regulatory agency			$ 655,000,000
NSTAR Electric | Commercial Paper
Short-term Debt [Line Items]
Maximum borrowing capacity	650,000,000
NSTAR Electric | Line of Credit
Short-term Debt [Line Items]
Maximum borrowing capacity	$ 650,000,000
Debt instrument term (in years)	5 years
PSNH
Short-term Debt [Line Items]
Short-term borrowing limit approved by regulatory agency	$ 443,500,000
Notes payable to related parties	$ 173,300,000	$ 110,600,000
PSNH | Short Term Debt Authorization Calculation
Short-term Debt [Line Items]
Interest rate	10.00%
Short-term debt borrowing calculation approved by regulatory agency	$ 60,000,000
PSNH | Line of Credit
Short-term Debt [Line Items]
Maximum borrowing capacity	$ 300,000,000