AFFILIATIONS, DISCONTINUED OPERATIONS AND RELATED-PARTY TRANSACTIONS - Related Party Transactions (Details) - South Jersey Gas Company - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Related Party Transaction [Line Items]
Total Operating Revenues/Affiliates	$ 20,150	$ 7,623	$ 5,513
Total Operations Expense/Affiliates	33,838	34,791	29,121
SJRG
Related Party Transaction [Line Items]
Total Operating Revenues/Affiliates	20,067	7,483	5,039
Cost of Sales/Affiliates	5,013	4,969	9,612
Marina
Related Party Transaction [Line Items]
Total Operating Revenues/Affiliates	0	60	394
SJI (parent company only)
Related Party Transaction [Line Items]
Total Operations Expense/Affiliates	25,919	26,173	22,462
SJIU
Related Party Transaction [Line Items]
Total Operations Expense/Affiliates	4,281	3,825	1,833
Millennium
Related Party Transaction [Line Items]
Total Operations Expense/Affiliates	3,458	3,277	3,146
Other
Related Party Transaction [Line Items]
Total Operating Revenues/Affiliates	83	80	80
Total Operations Expense/Affiliates	$ 180	$ 1,516	$ 1,680