COMMITMENTS AND CONTINGENCIES (Details)		1 Months Ended	3 Months Ended		6 Months Ended
	May 08, 2017 USD ($)	Jul. 31, 2017	Jun. 30, 2017 USD ($) site union decatherm / day contract	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) site union decatherm / day contract	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Commitment and Contingencies [Line Items]
Percentage of personnel represented by collective bargaining agreements			42.00%		42.00%
Number of unions | union			2		2
Cost of Sales - Nonutility			$ 147,354,000	$ 78,832,000	$ 363,117,000	$ 166,601,000
Interest Charges			10,979,000	8,229,000	27,724,000	17,389,000
Approximate amount accrued related to all claims			$ 3,000,000		$ 3,000,000		$ 3,100,000
Environmental restoration costs
Commitment and Contingencies [Line Items]
Number of sites for environmental cleanup | site			12		12
Pricing dispute, long-term gas supply contract
Commitment and Contingencies [Line Items]
Number of long-term gas supply contracts | contract			2		2
Line of Credit
Commitment and Contingencies [Line Items]
Letter of credit provided			$ 660,000,000		$ 660,000,000
Standby letters of credit
Commitment and Contingencies [Line Items]
Letter of credit provided			$ 9,800,000		9,800,000
South Jersey Gas Company
Commitment and Contingencies [Line Items]
Cumulative obligation for demand charges and reservation fees per month					$ 5,100,000
Percentage of personnel represented by collective bargaining agreements			59.00%		59.00%
Interest Charges			$ 6,077,000	$ 4,552,000	$ 11,955,000	$ 9,339,000
Approximate amount accrued related to all claims			700,000		700,000		$ 600,000
South Jersey Gas Company | Pricing dispute, long-term gas supply contract | Judicial ruling
Commitment and Contingencies [Line Items]
Amount to be paid to supplier	$ 16,700,000
South Jersey Gas Company | Line of Credit
Commitment and Contingencies [Line Items]
Letter of credit provided			210,000,000		210,000,000
South Jersey Gas Company | Revolving Credit Facilities | Line of Credit
Commitment and Contingencies [Line Items]
Letter of credit provided			200,000,000		200,000,000
Letters of credit outstanding			800,000		800,000
South Jersey Gas Company | Letters of credit under separate facility
Commitment and Contingencies [Line Items]
Letter of credit provided			$ 25,200,000		25,200,000
South Jersey Resources Group
Commitment and Contingencies [Line Items]
Cumulative obligation for demand charges and reservation fees per month					$ 500,000
Minimum purchase commitment (in dts/d) | decatherm / day			635,000		635,000
Maximum purchase commitment (in dts/d) | decatherm / day			901,500		901,500
Minimum length of contract					3 years
Maximum length of contract					10 years
South Jersey Resources Group | Pricing dispute, long-term gas supply contract | Judicial ruling
Commitment and Contingencies [Line Items]
Amount to be paid to supplier	$ 45,000,000
Cost of Sales - Nonutility			$ 400,000		$ 41,000,000
Interest Charges			600,000		4,000,000
South Jersey Resources Group | Dispute, long-term management contract | Pending litigation
Commitment and Contingencies [Line Items]
Amount to be paid to supplier					9,500,000
Amount claimed to be owed					13,300,000
Parental guarantee
Commitment and Contingencies [Line Items]
Parental guarantees			$ 6,100,000		$ 6,100,000
Guarantee expiration period					2 years
Subsequent event | South Jersey Resources Group | Dispute, long-term management contract | Pending litigation
Commitment and Contingencies [Line Items]
Term of capacity management contract		3 years