MARKETABLE SECURITIES (Tables)

3 Months Ended

Mar. 31, 2013

Notes To Consolidated Financial Statements [Abstract]

Schedule Of Available For Sale Securities Reconciliation [Table TextBlock]

		As of March 31, 2013
				Pre-Tax		Pre-Tax
		Amortized		Unrealized		Unrealized
(Millions of Dollars)		Cost		Gains(1)		Losses(1)		Fair Value
NU
	Debt Securities (2)	$	355.3	$	10.0	$	(0.1)	$	365.2
	Equity Securities (2)		144.0		30.7		-		174.7
WMECO
	Debt Securities		57.7		0.1		-		57.8
		As of December 31, 2012
				Pre-Tax		Pre-Tax
		Amortized		Unrealized		Unrealized
(Millions of Dollars)		Cost		Gains(1)		Losses(1)		Fair Value
NU
	Debt Securities (2)	$	266.6	$	13.3	$	(0.1)	$	279.8
	Equity Securities (2)		145.5		20.0		-		165.5
WMECO
	Debt Securities		57.7		0.1		(0.1)		57.7

Investments Classified by Contractual Maturity Date [Table Text Block]

	NU				WMECO
	Amortized				Amortized
(Millions of Dollars)	Cost		Fair Value		Cost		Fair Value
Less than one year (1)	$	150.7	$	150.8	$	30.4	$	30.6
One to five years		62.2		63.5		18.7		18.5
Six to ten years		51.2		53.4		4.1		4.1
Greater than ten years		91.2		97.5		4.5		4.6
Total Debt Securities	$	355.3	$	365.2	$	57.7	$	57.8

Fair Value Heirarchy [Table Text Block]

			NU				WMECO
			As of				As of
(Millions of Dollars)			March 31, 2013		December 31, 2012		March 31, 2013		December 31, 2012
Level 1:
	Mutual Funds and Equities		$	225.9	$	212.5	$	-	$	-
	Money Market Funds			120.1		40.2		3.6		5.2
Total Level 1			$	346.0	$	252.7	$	3.6	$	5.2
Level 2:
	U.S. Government Issued Debt Securities
		(Agency and Treasury)	$	78.5	$	69.9	$	18.2	$	18.7
	Corporate Debt Securities			41.1		33.0		11.7		7.0
	Asset-Backed Debt Securities			26.4		28.5		9.6		10.9
	Municipal Bonds			82.6		93.8		8.6		11.6
	Other Fixed Income Securities			16.5		14.4		6.1		4.3
Total Level 2			$	245.1	$	239.6	$	54.2	$	52.5
Total Marketable Securities			$	591.1	$	492.3	$	57.8	$	57.7