COMMITMENTS AND CONTINGENCIES - Schedule of Number of Sites and Reserves (Details) - site	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Loss Contingencies [Line Items]
Number of Sites	61	63
The Connecticut Light and Power Company
Loss Contingencies [Line Items]
Number of Sites	14	15
NSTAR Electric Company
Loss Contingencies [Line Items]
Number of Sites	11	12
Public Service Company of New Hampshire
Loss Contingencies [Line Items]
Number of Sites	9	9