DERIVATIVE INSTRUMENTS (Details) MWh in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) MWh	Dec. 31, 2016 USD ($) MMcfe
Marina Energy LLC | Interest Rate Swap, 14,500,000
Derivative [Line Items]
Notional Amount	$ 14,500,000	$ 14,500,000
Fixed Interest Rate	3.905%	3.905%
Marina Energy LLC | Interest Rate Swap, 500,000
Derivative [Line Items]
Notional Amount	$ 500,000	$ 500,000
Fixed Interest Rate	3.905%	3.905%
Marina Energy LLC | Interest Rate Swap, 330,000
Derivative [Line Items]
Notional Amount	$ 330,000	$ 330,000
Fixed Interest Rate	3.905%	3.905%
South Jersey Gas Company | Interest Rate Swap, 12,500,000, Contract 1
Derivative [Line Items]
Notional Amount	$ 12,500,000	$ 12,500,000
Fixed Interest Rate	3.53%	3.53%
South Jersey Gas Company | Interest Rate Swap, 12,500,000, Contract 2
Derivative [Line Items]
Notional Amount	$ 12,500,000	$ 12,500,000
Fixed Interest Rate	3.43%	3.43%
Basis and index related purchase and sales contracts
Derivative [Line Items]
Notional amount (natural gas in mmcfe and electricity in mwh) | MMcfe		141,600
Expected future purchases
Derivative [Line Items]
Notional amount (natural gas in mmcfe and electricity in mwh)	2.3	67,900
Expected future sales
Derivative [Line Items]
Notional amount (natural gas in mmcfe and electricity in mwh)	1.7	62,100