DERIVATIVE INSTRUMENTS - Narrative (Details) - NSTAR Electric	1 Months Ended
	Jun. 30, 2018	Mar. 31, 2026 MWh MW	Dec. 31, 2025 MWh
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Power purchase agreement	20 years
Amount of power to be purchased under capacity-related contract (in MW) | MW		579
Minimum | Level 3
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Energy price		27.16	24.65
Maximum | Level 3
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Energy price		190.27	145.33
Weighted Average | Level 3
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Energy price		56.12	53.44