DERIVATIVE INSTRUMENTS - DERIVATIVE INSTRUMENTS AND THE ACTIVE INTEREST SWAPS (Details) MWh in Millions	3 Months Ended
	Mar. 31, 2016 USD ($) MWh	Mar. 31, 2016 USD ($) MMcfe
Marina | Interest Rate Swap, $14,500,000 Contract
Derivative [Line Items]
Derivative, Notional Amount	$ 14,500,000	$ 14,500,000
Derivative, Fixed Interest Rate	3.905%	3.905%
Marina | Interest Rate Swap, $500,000 Contract
Derivative [Line Items]
Derivative, Notional Amount	$ 500,000	$ 500,000
Derivative, Fixed Interest Rate	3.905%	3.905%
Marina | Interest Rate Swap, $330,000 Contract
Derivative [Line Items]
Derivative, Notional Amount	$ 330,000	$ 330,000
Derivative, Fixed Interest Rate	3.905%	3.905%
SJG | Interest Rate Swap, $12,500,000 Contract 1
Derivative [Line Items]
Derivative, Notional Amount	$ 12,500,000	$ 12,500,000
Derivative, Fixed Interest Rate	3.53%	3.53%
SJG | Interest Rate Swap, $12,500,000 Contract 2
Derivative [Line Items]
Derivative, Notional Amount	$ 12,500,000	$ 12,500,000
Derivative, 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		169,600
Derivative Transaction Type, Purchase
Derivative [Line Items]
Notional amount (natural gas in mmcfe and electricity in mwh)	2.6	71,900
Derivative Transaction Type, Sale
Derivative [Line Items]
Notional amount (natural gas in mmcfe and electricity in mwh)	2.4	59,200