FINANCIAL INSTRUMENTS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Restricted investments held In escrow	$ 300	$ 300
Margin accounts with selected counterparties to support risk management activities	16,400	31,600
Cash and Cash Equivalents	6,312	7,819
Restricted Investments	16,713	31,876
Total cash, cash equivalents and restricted cash shown in the statement of cash flows	23,025	39,695	$ 17,913	$ 31,910
Notes Receivable - Affiliate	$ 13,275	13,275
Energenic US LLC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Equity interest	50.00%
Notes Receivable - Affiliate	$ 13,600
South Jersey Gas Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Margin accounts with selected counterparties to support risk management activities	2,300	2,900
Cash and Cash Equivalents	3,398	1,707
Restricted Investments	2,322	2,912
Total cash, cash equivalents and restricted cash shown in the statement of cash flows	5,720	4,619	$ 4,287	$ 1,391
South Jersey Gas Company | Financing Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount of loans, net of unamortized discounts	6,600	7,000
Imputed interest of loans	$ 700	$ 700
South Jersey Gas Company | Financing Receivable | Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Initial term of note	5 years
South Jersey Gas Company | Financing Receivable | Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Initial term of note	10 years