LINES OF CREDIT AND SHORT-TERM BORROWINGS - SCHEDULE OF CREDIT FACILITIES AND AVAILABLE LIQUIDITY (Details) - USD ($)	Dec. 31, 2020	Mar. 26, 2020
Line of Credit
Line of Credit Facility [Line Items]
Total Facility	$ 1,060,000,000
Usage	607,800,000
Available Liquidity	452,200,000
Unsecured debt | Unsecured Term Loan
Line of Credit Facility [Line Items]
Available Liquidity	0
South Jersey Industries Inc. | Line of Credit
Line of Credit Facility [Line Items]
Total Facility	650,000,000
Usage	484,600,000
Available Liquidity	165,400,000
South Jersey Industries Inc. | Line of Credit | Line of Credit
Line of Credit Facility [Line Items]
Total Facility	500,000,000.0
Usage	334,600,000
Available Liquidity	165,400,000
Letters of credit outstanding	9,600,000
South Jersey Industries Inc. | Unsecured debt | Unsecured Term Loan
Line of Credit Facility [Line Items]
Total Facility	150,000,000	$ 150,000,000.0
Usage	150,000,000
South Jersey Gas Company | Line of Credit
Line of Credit Facility [Line Items]
Total Facility	210,000,000
Usage	48,300,000
Available Liquidity	161,700,000
South Jersey Gas Company | Line of Credit | Line of Credit
Line of Credit Facility [Line Items]
Letters of credit outstanding	800,000
South Jersey Gas Company | Line of Credit | Revolving Credit Facility
Line of Credit Facility [Line Items]
Total Facility	200,000,000.0
South Jersey Gas Company | Line of Credit | Uncommitted Bank Lines
Line of Credit Facility [Line Items]
Total Facility	10,000,000
Usage	0
Available Liquidity	10,000,000
South Jersey Gas Company | Commercial Paper and Letters of Credit | Revolving Credit Facility
Line of Credit Facility [Line Items]
Total Facility	200,000,000
Usage	48,300,000
Available Liquidity	151,700,000
ETG/SJIU | Line of Credit | Line of Credit
Line of Credit Facility [Line Items]
Letters of credit outstanding	1,000,000.0
ETG/SJIU | Line of Credit | Revolving Credit Facility
Line of Credit Facility [Line Items]
Total Facility	200,000,000
Usage	74,900,000
Available Liquidity	$ 125,100,000