Equity Method Investments (Tables)

12 Months Ended

Dec. 31, 2015

Notes To Consolidated Financial Statements [Abstract]

Schedule of Equity Method Investments [Table Text Block]

	Ownership Interests (percent)						Carrying Amount (in millions)
	As of December 31, 2015 and 2014						As of December 31,
	CYAPC		YAEC		MYAPC		2015		2014
CL&P	34.5	%	24.5	%	12.0	%	$	1.2	$	1.2
NSTAR Electric	14.0		14.0		4.0			0.5		0.5
PSNH	5.0		7.0		5.0			0.3		0.3
WMECO	9.5		7.0		3.0			0.3		0.3