LINES OF CREDIT AND SHORT-TERM BORROWINGS - Schedule of Lines of Credit (Weighted Average Interest Rates, Average Borrowings, and Maximum Amounts Outstanding) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Line of Credit Facility [Line Items]
Maximum amounts outstanding	$ 366,800	$ 159,800	$ 375,300	$ 452,900
SJG
Line of Credit Facility [Line Items]
Maximum amounts outstanding	110,300	87,300	$ 110,300	$ 87,300
Line of Credit
Line of Credit Facility [Line Items]
Weighted average interest rate on borrowings (as a percent)			3.90%	0.69%
Average borrowings outstanding, not including LOC	249,350	83,500	$ 209,811	$ 169,000
Line of Credit | SJG
Line of Credit Facility [Line Items]
Weighted average interest rate on borrowings (as a percent)			1.42%	0.18%
Average borrowings outstanding, not including LOC	$ 40,150	$ 47,000	$ 35,644	$ 24,200