FINANCIAL INSTRUMENTS - RESTRICTED CASH (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and Cash Equivalents	$ 30,030	$ 7,819
Restricted Investments	1,649	31,876
Total cash, cash equivalents and restricted cash shown in the statement of cash flows	31,679	39,695	$ 31,910	$ 52,635
South Jersey Gas Company
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and Cash Equivalents	1,984	1,707
Restricted Investments	1,278	2,912
Total cash, cash equivalents and restricted cash shown in the statement of cash flows	$ 3,262	$ 4,619	$ 1,391	$ 7,544