GOODWILL (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Line item]
Goodwill Acquired During Period	$ 3,200,000
Goodwill		$ 3,519,401	$ 3,519,401
Yankee Gas Services Company [Member]
Goodwill [Line item]
Goodwill		300,000	300,000
Electric Distribution Member
Goodwill [Line item]
Goodwill		2,500,000	2,500,000
Electric Transmission [Member]
Goodwill [Line item]
Goodwill		600,000	600,000
Natural Gas Distribution [Member]
Goodwill [Line item]
Goodwill		$ 400,000	$ 400,000