DERIVATIVE INSTRUMENTS (Tables)

3 Months Ended

Mar. 31, 2026

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Derivative Instruments in Statement of Financial Position, Fair Value

The following table presents the fair values of derivative contracts, categorized by risk type, which are recorded as current or long-term derivative assets or liabilities:

NSTAR Electric (Millions of Dollars)	Fair Value Hierarchy	Commodity Supply and Price Risk Management
		As of March 31, 2026		As of December 31, 2025
Current Derivative Assets	Level 3	$	131.2	$	91.0
Long-Term Derivative Liabilities	Level 3	(636.2)		(753.1)

Schedule of Derivative Assets and Derivative Liabilities Measured at Fair Value

The following table presents changes in the Level 3 category of derivative assets and derivative liabilities measured at fair value on a recurring basis.  The derivative assets and liabilities are presented on a net basis in the following table.

NSTAR Electric (Millions of Dollars)	For the Three Months Ended
	March 31, 2026
Derivatives, Net:
Fair Value as of Beginning of Year	$	(662.1)
Net Realized/Unrealized Gains Included in Regulatory Assets and Liabilities	220.5
Settlements	(63.4)
Fair Value as of End of Year	$	(505.0)