LINES OF CREDIT (Details)	9 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)
Line of Credit Facility [Line Items]
Total Facility	$ 610,000,000
Usage	360,100,000
Available Liquidity	$ 249,900,000
Weighted average borrowing cost	1.03%	0.83%
Average borrowings outstanding during the period	$ 310,800,000	$ 291,600,000
Maximum amounts outstanding during the period	$ 432,400,000	$ 390,700,000
Minimum
Line of Credit Facility [Line Items]
Financial covenant, ratio of indebtedness to consolidated total capitalization minimum	0.65
SJG Commercial Paper Program
Line of Credit Facility [Line Items]
Total Facility	$ 200,000,000
Fixed maturities of notes, at maximum number of days (in days)	270 days
South Jersey Gas Company
Line of Credit Facility [Line Items]
Total Facility	$ 210,000,000
Usage	89,900,000
Available Liquidity	120,100,000
South Jersey Gas Company | Revolving Credit Facility
Line of Credit Facility [Line Items]
Total Facility	200,000,000
Usage	89,900,000
Available Liquidity	110,100,000
Letters of credit outstanding	600,000
South Jersey Gas Company | Uncommitted Bank Lines
Line of Credit Facility [Line Items]
Total Facility	10,000,000
Usage	0
Available Liquidity	10,000,000
South Jersey Industries Inc
Line of Credit Facility [Line Items]
Total Facility	400,000,000
Usage	270,200,000
Available Liquidity	129,800,000
South Jersey Industries Inc | Revolving Credit Facility
Line of Credit Facility [Line Items]
Total Facility	400,000,000
Usage	270,200,000
Available Liquidity	129,800,000
Letters of credit outstanding	$ 8,100,000