COMMITMENTS AND CONTINGENCIES (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2016 USD ($) site unions	Dec. 31, 2015 USD ($)
Collective bargaining agreements [Abstract]
Percentage of personnel represented by collective bargaining agreements	45.00%
Number of unions (in unions) | unions	2
Pending litigation [Abstract]
Estimated litigation liability	$ 3,300	$ 3,200
Environmental Restoration Costs
Environmental remediation costs [Abstract]
Number of sites for environmental cleanup (in number of sites) | site	12
Line of Credit
Collective bargaining agreements [Abstract]
Letter of credit provided	$ 610,000
Line of Credit | South Jersey Gas Company
Collective bargaining agreements [Abstract]
Letter of credit provided	210,000
Line of Credit | South Jersey Gas Company | Revolving Credit Facility
Collective bargaining agreements [Abstract]
Letters of credit outstanding	2,100
Standby Letter of Credit
Collective bargaining agreements [Abstract]
Letter of credit provided	3,300
Letter of Credit, Separate Facility
Collective bargaining agreements [Abstract]
Letter of credit provided	87,500
Parental Guarantee
Guarantees [Abstract]
Guaranteed amount	$ 6,200
Guarantee expiration period	2 years