FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)

6 Months Ended

Jun. 30, 2018

Fair Value Disclosures [Abstract]

Fair Value, by Balance Sheet Grouping

Carrying amounts and estimated fair values are as follows:

	Eversource				CL&P				NSTAR Electric				PSNH
(Millions of Dollars)	Carrying Amount		Fair Value		Carrying Amount		Fair Value		Carrying Amount		Fair Value		Carrying Amount		Fair Value
As of June 30, 2018:
Preferred Stock Not Subject to Mandatory Redemption	$	155.6	$	156.4	$	116.2	$	113.9	$	43.0	$	42.5	$	—	$	—
Long-Term Debt	12,396.6		12,501.7		3,253.3		3,473.3		2,944.3		3,019.9		894.0		909.0
Rate Reduction Bonds	635.7		638.3		—		—		—		—		635.7		638.3
As of December 31, 2017:
Preferred Stock Not Subject to Mandatory Redemption	$	155.6	$	160.8	$	116.2	$	116.5	$	43.0	$	44.3	$	—	$	—
Long-Term Debt	12,325.5		12,877.1		3,059.1		3,430.5		2,943.8		3,156.5		1,002.4		1,038.2