FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)

9 Months Ended

Sep. 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 September 30, 2018:
Preferred Stock Not Subject to Mandatory Redemption	$	155.6	$	163.0	$	116.2	$	120.2	$	43.0	$	42.8	$	—	$	—
Long-Term Debt	12,538.8		12,517.4		3,253.6		3,420.4		2,944.6		2,990.0		894.1		904.3
Rate Reduction Bonds	635.7		631.3		—		—		—		—		635.7		631.3
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