RATES AND REGULATORY ACTIONS (Details) - USD ($) $ in Thousands		1 Months Ended				3 Months Ended	6 Months Ended	12 Months Ended	15 Months Ended
	Apr. 01, 2021	Jun. 30, 2021	May 31, 2021	Apr. 30, 2021	Jan. 31, 2021	Jun. 30, 2021	Jun. 30, 2021	Jun. 30, 2021	Sep. 30, 2021	Mar. 31, 2021	Dec. 31, 2020
ETG Utility Operations
Schedule of Capitalization [Line Items]
Regulatory liability		$ 179,417				$ 179,417	$ 179,417	$ 179,417			$ 175,217
ETG Utility Operations | Annual BGSS Filing
Schedule of Capitalization [Line Items]
Requested revenue increase (decrease)						14,000
ETG Utility Operations | Annual USF Petition
Schedule of Capitalization [Line Items]
Requested revenue increase (decrease)						3,500
SJG
Schedule of Capitalization [Line Items]
Approved rate increase (decrease)							12,800
Regulatory liability		225,409				225,409	225,409	225,409			245,360
Public utilities, property, plant and equipment		2,864,207				2,864,207	2,864,207	2,864,207			$ 2,780,906
Requested revenue increase (decrease)							11,600
SJG | Annual BGSS Filing
Schedule of Capitalization [Line Items]
Approved rate increase (decrease)							59,500
SJG | Annual CIP Filing
Schedule of Capitalization [Line Items]
Approved rate increase (decrease)							15,300
SJG | SHARP II
Schedule of Capitalization [Line Items]
Requested revenue increase (decrease)						2,200		22,600
SJG | Accelerated Infrastructure Replacement Program
Schedule of Capitalization [Line Items]
Requested revenue increase (decrease)							5,700
SJG | Accelerated Infrastructure Replacement Program | Forecast
Schedule of Capitalization [Line Items]
Requested revenue increase (decrease)									$ 58,700
SJG | Universal Service Fund And L L Programs
Schedule of Capitalization [Line Items]
Approved rate increase (decrease)							3,800
SJG | Pricing dispute, long-term gas supply contract | Settled Litigation
Schedule of Capitalization [Line Items]
Recovery of costs			$ 22,900
New Jersey Board of Public Utilities | ETG Utility Operations
Schedule of Capitalization [Line Items]
Approved rate increase (decrease)	$ (3,200)
New Jersey Board of Public Utilities | ETG Utility Operations | IIP Investments
Schedule of Capitalization [Line Items]
Public utilities, property, plant and equipment		63,800				63,800	$ 63,800	$ 63,800
Requested revenue increase (decrease)						$ 7,100
Annual EET Rate Adjustment | SJG
Schedule of Capitalization [Line Items]
Approved rate increase (decrease)					$ 5,900
Annual Tax Act Rider | SJG | Protected Excess Deferred Income Tax
Schedule of Capitalization [Line Items]
Regulatory liability										$ 14,900
Societal Benefits Clause | New Jersey Board of Public Utilities | SJG
Schedule of Capitalization [Line Items]
Approved rate increase (decrease)				$ 5,500
Annual EEP Rate Adjustment | ETG Utility Operations
Schedule of Capitalization [Line Items]
Approved rate increase (decrease)		$ (500)
Annual EEP Rate Adjustment | New Jersey Board of Public Utilities | SJG
Schedule of Capitalization [Line Items]
Approved rate period				3 years
Public utilities, property, plant and equipment				$ 133,300
Requested revenue increase (decrease)				5,400
Annual EEP Rate Adjustment | New Jersey Board of Public Utilities | ETG Utility Operations
Schedule of Capitalization [Line Items]
Public utilities, property, plant and equipment				83,400
Requested revenue increase (decrease)				$ 2,800