COMMITMENTS AND CONTINGENCIES (Details)		1 Months Ended		3 Months Ended		9 Months Ended		33 Months Ended
	Jul. 01, 2018 USD ($)	Oct. 31, 2019 USD ($)	Sep. 30, 2019 USD ($) contract site decatherm	Sep. 30, 2019 USD ($) contract site decatherm	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) contract site decatherm	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) contract site decatherm	Dec. 31, 2018 USD ($) $ / 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%	45.00%		45.00%		45.00%
Interest charges				$ 28,857,000	$ 26,534,000	$ 85,944,000	$ 60,067,000
Litigation expense paid			$ 59,300,000
Approximate amount accrued related to all claims			$ 2,800,000	$ 2,800,000		$ 2,800,000		$ 2,800,000	$ 3,200,000
Subsequent event
Loss Contingencies [Line Items]
Litigation expense paid		$ 22,900,000
Pricing dispute, long-term gas supply contract
Loss Contingencies [Line Items]
Number of long-term gas supply contracts | contract			2	2		2		2
Standby letters of credit
Loss Contingencies [Line Items]
Total Facility			$ 9,600,000	$ 9,600,000		$ 9,600,000		$ 9,600,000
SJG
Loss Contingencies [Line Items]
Cumulative obligation for demand charges and reservation fees per month						$ 6,900,000
Percentage of personnel represented, collective bargaining agreements			69.00%	69.00%		69.00%		69.00%
Charges to cost of sales				$ 19,268,000	16,079,000	$ 140,802,000	125,266,000
Interest charges				7,840,000	7,108,000	23,584,000	20,835,000
Approximate amount accrued related to all claims			$ 600,000	600,000		600,000		$ 600,000	$ 900,000
SJG | Pricing dispute, long-term gas supply contract | Judicial Ruling
Loss Contingencies [Line Items]
Amount to be paid to supplier								22,900,000
SJG | Letter of credit
Loss Contingencies [Line Items]
Total Facility			800,000	800,000		800,000		800,000
SJG | Letter of credit under separate facility
Loss Contingencies [Line Items]
Total Facility			25,100,000	25,100,000		25,100,000		25,100,000
ETG Utility Operations | Letter of credit
Loss Contingencies [Line Items]
Total Facility			$ 1,000,000.0	$ 1,000,000.0		1,000,000.0		$ 1,000,000.0
South Jersey Resources Group, LLC
Loss Contingencies [Line Items]
Cumulative obligation for demand charges and reservation fees per month						$ 1,300,000
Maximum purchase commitment (in dts/d) | decatherm			832,500	832,500		832,500		832,500
Minimum length of contract						4 years
Maximum length of contract						10 years
South Jersey Resources Group, LLC | Pricing dispute, long-term gas supply contract | Judicial Ruling
Loss Contingencies [Line Items]
Amount to be paid to supplier								$ 59,300,000
Interest charges				$ 400,000	300,000	$ 1,100,000	700,000
Accounts Payable | SJG | Pricing dispute, long-term gas supply contract | Judicial Ruling
Loss Contingencies [Line Items]
Amount to be paid to supplier								22,900,000
Accounts Payable | South Jersey Resources Group, LLC | Pricing dispute, long-term gas supply contract | Judicial Ruling
Loss Contingencies [Line Items]
Amount to be paid to supplier								59,300,000
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			$ 10,600,000	$ 10,600,000		$ 10,600,000		$ 10,600,000
Guarantee expiration period						2 years
ETG Utility Operations
Loss Contingencies [Line Items]
Cumulative obligation for demand charges and reservation fees per month						$ 5,100,000
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			6	6		6		6
Nonutility Operations
Loss Contingencies [Line Items]
Charges to cost of sales				$ 163,914,000	209,874,000	$ 526,472,000	533,440,000
Nonutility Operations | South Jersey Resources Group, LLC | Pricing dispute, long-term gas supply contract | Judicial Ruling
Loss Contingencies [Line Items]
Charges to cost of sales					$ 1,400,000	$ 500,000	$ 2,700,000