LINES OF CREDIT (Details)	9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)
Line of Credit Facility [Line Items]
Total Facility	$ 210,000,000
Usage	81,800,000
Available Liquidity	$ 128,200,000
Financial covenant, ratio of indebtedness to consolidated total capitalization (not more than)	0.65
Average borrowings outstanding	$ 64,500,000	$ 117,900,000
Maximum amounts outstanding	$ 141,700,000	$ 162,300,000
Weighted average borrowing cost	0.76%	0.40%
Revolving Credit Facility
Line of Credit Facility [Line Items]
Total Facility	$ 200,000,000
Usage	81,800,000
Available Liquidity	118,200,000
Letters of credit outstanding	800,000
Uncommitted Bank Lines
Line of Credit Facility [Line Items]
Total Facility	10,000,000
Usage	0
Available Liquidity	10,000,000
South Jersey Gas 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