Regulation and Rates Narrative (Details) (New England Gas Company [Member], USD $)	0 Months Ended		3 Months Ended	12 Months Ended
	Nov. 13, 2009	Sep. 15, 2008	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012
New England Gas Company [Member]
Regulated Operations [Line Items]
Recovery amount requested based on previous years' earnings below return on equity of 7%		$ 4,000,000
Recovery percentage requested of earnings below stated return on equity	50.00%	50.00%
Adjusted Earnings Share Adjustment recovery requested	2,000,000	4,000,000
Remand Recovery Floor		7.00%
Earnings Share Adjustment recovery amount under investigation				2,000,000	2,000,000
Earnings Share Adjustment (ESA) recovery approved			4,000,000
Earnings Share Adjustment Recovery Amount Revision				$ 10,000