RATES AND REGULATORY ACTIONS (Details) - USD ($) $ in Thousands	1 Months Ended				3 Months Ended	9 Months Ended
	Sep. 30, 2020	Jul. 31, 2020	Jun. 30, 2020	May 31, 2020	Mar. 31, 2020	Sep. 30, 2020	Feb. 29, 2020	Dec. 31, 2019
ETG Utility Operations
Schedule of Capitalization [Line Items]
Regulatory liability	$ 175,637					$ 175,637		$ 168,436
Regulatory assets	173,654					173,654		169,231
ETG Utility Operations | Other Regulatory Assets
Schedule of Capitalization [Line Items]
Regulatory assets	18,000					18,000		9,004
ETG Utility Operations | Annual BGSS Filing
Schedule of Capitalization [Line Items]
Requested revenue increase (decrease)			$ (21,100)
ETG Utility Operations | Annual USF Petition
Schedule of Capitalization [Line Items]
Requested revenue increase (decrease)			(300)
SJG
Schedule of Capitalization [Line Items]
Regulatory liability	253,302					253,302		274,482
Regulatory assets	486,070					486,070		496,177
Public utilities, property, plant and equipment	2,707,480					2,707,480		2,596,102
SJG | Other Regulatory Assets
Schedule of Capitalization [Line Items]
Regulatory assets	25,889					25,889		$ 10,678
Increase (decrease) in regulatory assets						10,100
SJG | Annual BGSS Filing
Schedule of Capitalization [Line Items]
Approved rate increase (decrease)	$ (59,400)
Recovery term (in years)	2 years
SJG | Annual BGSS Filing | Pricing dispute, long-term gas supply contract | Settled Litigation
Schedule of Capitalization [Line Items]
Amount paid to third party supplier	$ 22,900
SJG | Annual CIP Filing
Schedule of Capitalization [Line Items]
Approved rate increase (decrease)	27,400
SJG | Annual USF Petition
Schedule of Capitalization [Line Items]
Approved rate increase (decrease)	(300)
New Jersey Board of Public Utilities | ETG Utility Operations | IIP Investments
Schedule of Capitalization [Line Items]
Requested revenue increase (decrease)		$ 6,800
Public utilities, property, plant and equipment		63,300
New Jersey Board of Public Utilities | SJG
Schedule of Capitalization [Line Items]
Approved rate increase (decrease)	$ 39,500
Approved rate of return on rate base, percentage	6.90%
Approved return on common equity, percentage	9.60%
Approved common equity component, percentage	54.00%
Amortization period (in years)	5 years
New Jersey Board of Public Utilities | SJG | Other Regulatory Assets
Schedule of Capitalization [Line Items]
Increase (decrease) in regulatory assets	$ 10,100
New Jersey Board of Public Utilities | SJG | AIRP II Investments
Schedule of Capitalization [Line Items]
Public utilities, property, plant and equipment	58,800					58,800
New Jersey Board of Public Utilities | SJG | SHARP II Investments
Schedule of Capitalization [Line Items]
Public utilities, property, plant and equipment	33,300					33,300
AIRP II | New Jersey Board of Public Utilities | SJG
Schedule of Capitalization [Line Items]
Approved rate increase (decrease)	6,400
SHARP II | New Jersey Board of Public Utilities | SJG
Schedule of Capitalization [Line Items]
Approved rate increase (decrease)	3,700
Stipulation of Settlement | SJG | Protected Excess Deferred Income Tax
Schedule of Capitalization [Line Items]
Net regulatory liability				$ 149,400
Regulatory liability				181,000
Regulatory assets				31,600
Stipulation of Settlement | SJG | Unprotected Excess Deferred Income Tax
Schedule of Capitalization [Line Items]
Credits due to customers under conditions of approval				$ 44,700
Public utilities, customer refund term (in years)				5 years
Annual EET Rate Adjustment | SJG
Schedule of Capitalization [Line Items]
Requested revenue increase (decrease)			$ 5,900
Annual SBC Petition | SJG
Schedule of Capitalization [Line Items]
Requested revenue increase (decrease)		5,500
Annual Tax Act Rider | SJG
Schedule of Capitalization [Line Items]
Public utilities, customer refund term (in years)				3 years
Annual Tax Act Rider | SJG | Protected Excess Deferred Income Tax
Schedule of Capitalization [Line Items]
Approved rate increase (decrease)	1,900
Annual Tax Act Rider | SJG | Unprotected Excess Deferred Income Tax
Schedule of Capitalization [Line Items]
Approved rate increase (decrease)	14,900
Annual RAC Rate Adjustment | ETG Utility Operations
Schedule of Capitalization [Line Items]
Requested revenue increase (decrease)		(3,200)			$ 6,100
Approved rate increase (decrease)					6,000
Annual EEP Rate Adjustment | ETG Utility Operations
Schedule of Capitalization [Line Items]
Requested revenue increase (decrease)	3,700	(200)			1,000
Approved rate increase (decrease)					$ 900
Annual EEP Rate Adjustment | SJG
Schedule of Capitalization [Line Items]
Requested revenue increase (decrease)	6,300
Annual EEP Rate Adjustment | New Jersey Board of Public Utilities | ETG Utility Operations
Schedule of Capitalization [Line Items]
Public utilities, property, plant and equipment	$ 100,000					$ 100,000
Public utilities budget							$ 4,200
Annual WNC/CEP/OSMC Rate Adjustment | ETG Utility Operations
Schedule of Capitalization [Line Items]
Requested revenue increase (decrease)		$ 8,500