COMMITMENTS AND CONTINGENCIES (Details)		6 Months Ended
	Jul. 01, 2018 USD ($)	Jun. 30, 2020 USD ($) decatherm site	Dec. 31, 2019 USD ($)	Dec. 31, 2018 $ / shares
Loss Contingencies [Line Items]
Minimum annual fee for long-term asset management agreement	$ 4,250,000
Percentage of personnel represented, collective bargaining agreements		45.00%
Approximate amount accrued related to all claims		$ 4,000,000.0	$ 3,100,000
SJG
Loss Contingencies [Line Items]
Cumulative obligation for demand charges and reservation fees per month		$ 7,800,000
Percentage of personnel represented, collective bargaining agreements		58.00%
Approximate amount accrued related to all claims		$ 1,000,000.0	$ 900,000
SJG | Environmental Remediation
Loss Contingencies [Line Items]
Number of sites for environmental cleanup | site		12
SJG | Letter of credit under separate facility
Loss Contingencies [Line Items]
Total Facility		$ 25,100,000
ETG Utility Operations
Loss Contingencies [Line Items]
Cumulative obligation for demand charges and reservation fees per month		4,800,000
South Jersey Resources Group, LLC
Loss Contingencies [Line Items]
Cumulative obligation for demand charges and reservation fees per month		$ 1,600,000
Maximum purchase commitment (in dts/d) | decatherm		731,250
Minimum length of contract		5 years
Maximum length of contract		11 years
Capital Units
Loss Contingencies [Line Items]
Corporate Unit, stated value per share (in dollars per share) | $ / shares				$ 50
Parental Guarantee
Loss Contingencies [Line Items]
Parental guarantees		$ 10,200,000
Guarantee expiration period		1 year
ETG Utility Operations
Loss Contingencies [Line Items]
Minimum annual fee for long-term asset management agreement		$ 4,250,000
ETG Utility Operations | Environmental Remediation
Loss Contingencies [Line Items]
Number of sites for environmental cleanup | site		5