PROPERTY, PLANT AND ACCUMULATED DEPRECIATION (Tables)

12 Months Ended

Dec. 31, 2015

Notes To Consolidated Financial Statements [Abstract]

Schedule of Public Utility Property, Plant, and Equipment [Text Block]

Eversource		As of December 31,
(Millions of Dollars)		2015		2014
Distribution - Electric		$	13,054.8	$	12,495.2
Distribution - Natural Gas			2,727.2		2,595.4
Transmission - Electric			7,691.9		6,930.7
Generation			1,194.1		1,170.9
Electric and Natural Gas Utility			24,668.0		23,192.2
Other (1)			558.6		551.3
Property, Plant and Equipment, Gross			25,226.6		23,743.5
Less: Accumulated Depreciation
	Electric and Natural Gas Utility		(6,141.1)		(5,777.8)
	Other		(255.6)		(231.8)
Total Accumulated Depreciation			(6,396.7)		(6,009.6)
Property, Plant and Equipment, Net			18,829.9		17,733.9
Construction Work in Progress			1,062.5		913.1
Total Property, Plant and Equipment, Net		$	19,892.4	$	18,647.0

	As of December 31,
	2015								2014
			NSTAR								NSTAR
(Millions of Dollars)	CL&P		Electric		PSNH		WMECO		CL&P		Electric		PSNH		WMECO
Distribution	$	5,377.2	$	5,100.5	$	1,804.8	$	812.3	$	5,158.8	$	4,895.5	$	1,696.7	$	784.2
Transmission		3,618.0		2,131.3		928.2		964.9		3,274.0		1,928.5		789.7		891.0
Generation		-		-		1,158.1		36.0		-		-		1,136.5		34.4
Property, Plant and Equipment, Gross		8,995.2		7,231.8		3,891.1		1,813.2		8,432.8		6,824.0		3,622.9		1,709.6
Less: Accumulated Depreciation		(2,041.9)		(1,886.8)		(1,171.0)		(307.0)		(1,928.0)		(1,761.4)		(1,090.0)		(297.4)
Property, Plant and Equipment, Net		6,953.3		5,345.0		2,720.1		1,506.2		6,504.8		5,062.6		2,532.9		1,412.2
Construction Work in Progress		203.5		310.5		135.3		69.1		304.9		272.8		102.9		49.1
Total Property, Plant and Equipment, Net	$	7,156.8	$	5,655.5	$	2,855.4	$	1,575.3	$	6,809.7	$	5,335.4	$	2,635.8	$	1,461.3

(Percent)	2015		2014		2013
Eversource	2.9	%	3.0	%	2.8	%
CL&P	2.7	%	2.7	%	2.5	%
NSTAR Electric	3.0	%	3.0	%	2.9	%
PSNH	3.2	%	3.0	%	3.0	%
WMECO	2.7	%	3.3	%	2.9	%

The following table summarizes average remaining useful lives of depreciable assets:
	As of December 31, 2015
(Years)	Eversource		CL&P		NSTAR Electric		PSNH		WMECO
Distribution		34.8		37.3		31.9		31.3		30.5
Transmission		41.6		38.7		43.8		41.6		50.0
Generation		30.7		-		-		30.9		25.0
Other		14.1		-		-		-		-