RELATED PARTY TRANSACTIONS (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating Revenues [Abstract]
Operating Revenues	$ 2,689	$ 1,735	$ 7,248
Energy-Related Derivative Losses	400	15,400	12,900
Operating Expenses [Abstract]
Operating Expenses	19,779	18,916	17,525
SJRG [Member]
Operating Revenues [Abstract]
Operating Revenues	1,390	884	6,532
Cost of Sales	14,959	9,083	33,768
Energy-Related Derivative Losses	887	15,407	12,872
SJI [Member]
Operating Expenses [Abstract]
Operating Expenses	11,990	10,870	9,941
SJIS [Member]
Operating Expenses [Abstract]
Operating Expenses	5,531	5,397	4,956
Millennium [Member]
Operating Expenses [Abstract]
Operating Expenses	2,686	3,149	3,076
Other [Member]
Operating Revenues [Abstract]
Operating Revenues	1,299	851	716
Operating Expenses [Abstract]
Operating Expenses	$ (428)	$ (500)	$ (448)