RELATED-PARTY TRANSACTIONS (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Related Party Transaction [Line Items]
Operating Revenues/Affiliates	$ 510	$ 614	$ 4,628	$ 1,898
Total Operations Expense/Affiliates	5,967	3,949	11,159	8,417
SJRG
Related Party Transaction [Line Items]
Operating Revenues/Affiliates	421	479	4,422	1,531
Costs of Sales/Affiliates (Excluding depreciation)	1,514	1,508	9,503	20,531
Energy-Related Derivative Losses / (Gains)	0	69	0	65
Marina
Related Party Transaction [Line Items]
Operating Revenues/Affiliates	89	135	206	367
SJI
Related Party Transaction [Line Items]
Total Operations Expense/Affiliates	5,315	3,364	9,870	7,281
Millennium
Related Party Transaction [Line Items]
Total Operations Expense/Affiliates	701	693	1,395	1,353
Other
Related Party Transaction [Line Items]
Other	$ (49)	$ (108)	$ (106)	$ (217)