COMMITMENTS AND CONTINGENCIES - Schedule of Number of Sites and Reserves (Details) - site	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Loss Contingencies [Line Items]
Number of sites	66	65
CL&P
Loss Contingencies [Line Items]
Number of sites	15	15
NSTAR Electric
Loss Contingencies [Line Items]
Number of sites	14	14
PSNH
Loss Contingencies [Line Items]
Number of sites	8	8