Operating Expenses (Tables)

12 Months Ended

Dec. 31, 2012

Notes To Consolidated Financial Statements [Abstract]

Schedule of Fuel Costs [Table Text Block]

	For the Years Ended December 31,
(Millions of Dollars)	2012(1)		2011		2010
NU	$	346.8	$	307.9	$	391.6
PSNH		103.4		115.9		184.3
Yankee Gas		145.9		191.3		206.4
NSTAR Gas		97.2		N/A		N/A
(1) Includes the NSTAR Gas costs from the date of the merger, April 10, 2012, through December 31, 2012.