ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) (Tables)

9 Months Ended

Sep. 30, 2023

Equity [Abstract]

Changes in Accumulated Other Comprehensive Income/(Loss) by Component, Net of Tax

The changes in accumulated other comprehensive income/(loss) by component, net of tax, are as follows:

	For the Nine Months Ended September 30, 2023								For the Nine Months Ended September 30, 2022
Eversource (Millions of Dollars)	Qualified Cash Flow Hedging Instruments		Unrealized Gains/(Losses) on Marketable Securities		Defined Benefit Plans		Total		Qualified Cash Flow Hedging Instruments		Unrealized Gains/(Losses) on Marketable Securities		Defined Benefit Plans		Total
Balance as of Beginning of Period	$	(0.4)	$	(1.2)	$	(37.8)	$	(39.4)	$	(0.4)	$	0.4	$	(42.3)	$	(42.3)
OCI Before Reclassifications	—		—		0.1		0.1		—		(2.0)		(2.5)		(4.5)
Amounts Reclassified from AOCI	—		1.2		14.1		15.3		—		—		5.8		5.8
Net OCI	—		1.2		14.2		15.4		—		(2.0)		3.3		1.3
Balance as of End of Period	$	(0.4)	$	—	$	(23.6)	$	(24.0)	$	(0.4)	$	(1.6)	$	(39.0)	$	(41.0)