REVENUES - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Total revenues from alternative revenue programs	$ 17.8	$ 38.1	$ 29.0
SJG Utility Operations
Disaggregation of Revenue [Line Items]
Total revenues from alternative revenue programs	$ 13.0	$ 28.0	$ 34.8