DERIVATIVE INSTRUMENTS - Summary of Level 3 Derivative Contracts and Significant Unobservable Inputs Used (Details) - CL&P - Forward Reserve Prices - Level 3 - $ / KWmo	Mar. 31, 2023	Dec. 31, 2022
Minimum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative measurement input	0.44	0.44
Maximum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative measurement input	0.50	0.50
Weighted Average
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative measurement input	0.47	0.47