LINES OF CREDIT AND SHORT-TERM BORROWINGS - Schedule of Lines of Credit (Details)	Sep. 30, 2022 USD ($)
Line of Credit
Line of Credit Facility [Line Items]
Total Facility	$ 1,000,000,000
Usage	212,200,000
Available Liquidity	787,800,000
SJI | Line of Credit | Line of Credit
Line of Credit Facility [Line Items]
Total Facility	500,000,000
Usage	7,100,000
Available Liquidity	492,900,000
Letters of credit outstanding	7,100,000
SJG | Line of Credit | Line of Credit
Line of Credit Facility [Line Items]
Letters of credit outstanding	1,900,000
SJG | Commercial Paper and Letters of Credit | Revolving Credit Facility
Line of Credit Facility [Line Items]
Total Facility	250,000,000
Usage	97,300,000
Available Liquidity	152,700,000
ETG | Line of Credit | Line of Credit
Line of Credit Facility [Line Items]
Letters of credit outstanding	0
ETG | Line of Credit | Revolving Credit Facility
Line of Credit Facility [Line Items]
Total Facility	250,000,000
Usage	107,800,000
Available Liquidity	$ 142,200,000