Other Retirement Benefits (Tables)

12 Months Ended

Dec. 31, 2015

Notes To Consolidated Financial Statements [Abstract]

Schedule of Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits by Title of Individual and Type of Deferred Compensation [Table Text Block]

Eversource	As of and For the Years Ended December 31,
(Millions of Dollars)	2015		2014		2013
Actuarially-Determined Liability	$	55.2	$	57.5	$	51.3
Other Retirement Benefits Expense		3.9		4.5		4.4

	As of and For the Years Ended December 31,
	2015								2014								2013
(Millions of Dollars)	CL&P		NSTAR Electric		PSNH		WMECO		CL&P		NSTAR Electric		PSNH		WMECO		CL&P		PSNH		WMECO
Actuarially-Determined Liability	$	0.4	$	-	$	2.4	$	0.2	$	0.4	$	-	$	2.6	$	0.2	$	0.4	$	2.3	$	0.1
Other Retirement Benefits Expense		1.5		1.0		0.7		0.3		2.1		0.3		0.9		0.4		2.5		1.0		0.5