FINANCIAL INSTRUMENTS - Cash, Cash Equivalents and Restricted Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Cash and Cash Equivalents [Line Items]
Cash and Cash Equivalents	$ 7,267	$ 6,417
Restricted Investments	11,402	21,964
Total cash, cash equivalents and restricted cash shown in the statement of cash flows	18,669	28,381	$ 31,212	$ 31,679
SJG
Cash and Cash Equivalents [Line Items]
Cash and Cash Equivalents	2,144	2,678
Restricted Investments	3,448	4,073
Total cash, cash equivalents and restricted cash shown in the statement of cash flows	$ 5,592	$ 6,751	$ 9,415	$ 3,262