UNUSED LINES OF CREDIT (Details) (USD $)	6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012
Line of Credit Facility [Line Items]
Total Facility	$ 210,000,000
Usage	93,000,000
Available Liquidity	117,000,000
Average borrowings outstanding during the period	81,000,000		137,100,000
Maximum amounts outstanding during the period	103,000,000		155,200,000
Weighted average borrowing cost	0.36%		0.48%
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Total Facility	200,000,000
Usage	93,000,000
Available Liquidity	107,000,000
Expiration Date	May 2015
Uncommitted Bank Lines [Member]
Line of Credit Facility [Line Items]
Total Facility	10,000,000	[1]
Usage	0	[1]
Available Liquidity	10,000,000	[1]
Expiration Date	August 2013	[1]
South Jersey Gas Commercial Paper Program [Member]
Line of Credit Facility [Line Items]
Total Facility	$ 200,000,000
Fixed maturities of notes, at maximum number of days (in days)	270 days
Minimum [Member]
Line of Credit Facility [Line Items]
Financial covenant, ratio of indebtedness to consolidated total capitalization minimum	0.65

[1] SJG anticipates renewing the remaining line of credit during the third quarter 2013.