FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value, by Balance Sheet Grouping

The fair values provided in the table below are classified as Level 2 within the fair value hierarchy.  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 December 31, 2018:
Preferred Stock Not Subject to Mandatory Redemption	$	155.6	$	156.8	$	116.2	$	113.8	$	43.0	$	43.0	$	—	$	—
Long-Term Debt	13,086.1		13,154.9		3,254.0		3,429.2		2,944.8		3,024.1		805.2		819.5
Rate Reduction Bonds	635.7		645.8		—		—		—		—		635.7		645.8
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