REVENUES - Receivables and Unbilled Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accounts Receivable
Disaggregation of Revenue [Line Items]
Contracts with customers, asset	$ 343,835	$ 278,723	$ 253,661
Increase (decrease) in contracts with customers, asset	65,112	25,062
Unbilled Revenue
Disaggregation of Revenue [Line Items]
Contracts with customers, asset	87,357	85,423	84,821
Increase (decrease) in contracts with customers, asset	1,934	602
SJG Utility Operations | Accounts Receivable
Disaggregation of Revenue [Line Items]
Contracts with customers, asset	125,848	88,657	84,940
Increase (decrease) in contracts with customers, asset	37,191	3,717
SJG Utility Operations | Unbilled Revenue
Disaggregation of Revenue [Line Items]
Contracts with customers, asset	43,236	46,837	$ 45,016
Increase (decrease) in contracts with customers, asset	$ (3,601)	$ 1,821