FINANCIAL INSTRUMENTS - RESTRICTED CASH (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and Cash Equivalents	$ 7,819	$ 18,282
Restricted Investments	31,876	13,628
Total cash, cash equivalents and restricted cash shown in the statement of cash flows	39,695	31,910	$ 52,635	$ 69,622
South Jersey Gas Company
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and Cash Equivalents	1,707	1,359
Restricted Investments	2,912	32
Total cash, cash equivalents and restricted cash shown in the statement of cash flows	$ 4,619	$ 1,391	$ 7,544	$ 9,739