UNUSED LINES OF CREDIT (Details) (USD $)	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Line of Credit Facility [Line Items]
Total Facility	$ 210,000,000
Usage	110,000,000
Available Liquidity	100,000,000
Average borrowings outstanding during the period	90,500,000	146,300,000
Maximum amounts outstanding during the period	119,900,000	180,500,000
Weighted average borrowing cost	0.34%	0.47%
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Total Facility	200,000,000
Usage	110,000,000
Available Liquidity	90,000,000
Expiration Date	May 2018
Uncommitted Bank Lines [Member]
Line of Credit Facility [Line Items]
Total Facility	10,000,000
Usage	0
Available Liquidity	10,000,000
Expiration Date	August 2014
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