SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)			1 Months Ended			3 Months Ended	12 Months Ended
	Jul. 31, 2020 USD ($)	Jul. 01, 2018 USD ($)	Aug. 31, 2021 USD ($)	Jul. 31, 2020 USD ($)	Feb. 29, 2020 USD ($)	Dec. 31, 2020 USD ($) shares	Dec. 31, 2021 USD ($) county project shares	Dec. 31, 2020 USD ($) entity shares	Dec. 31, 2019 USD ($) project	Jun. 30, 2021	Aug. 31, 2020	Aug. 12, 2020	Aug. 07, 2020	Aug. 06, 2020
Schedule of Equity Method Investments [Line Items]
Number of solar energy projects | project							2
Number of business acquired | entity								3
Gains (loss) on sale of projects							$ 0	$ 2,578,000	$ 3,133,000
Depreciation expense on reclassified assets						$ 5,300,000
Impairment charges									$ 10,800,000
Number of unsold solar energy sites | project									2
Useful life (in years)							15 years
Interest capitalized							$ 5,700,000	$ 7,100,000	$ 6,000,000
Treasury stock held (in shares) | shares						256,372	229,978	256,372
Income tax credits							$ 3,900,000	$ 21,300,000	$ 0
Payments to purchase asset management agreement		$ 11,300,000
Intangible asset		19,200,000				$ 6,400,000	1,300,000	6,400,000
Profit sharing liabilities		$ 17,546,000				$ 7,000,000	$ 3,500,000	$ 7,000,000
New Jersey Division of Taxation
Schedule of Equity Method Investments [Line Items]
Energy and Other Taxes			$ 11,000,000
REV LNG
Schedule of Equity Method Investments [Line Items]
Equity interest (as a percent)						35.00%	35.00%	35.00%
Minimum
Schedule of Equity Method Investments [Line Items]
Renewal lease term (in years)							1 year
Maximum
Schedule of Equity Method Investments [Line Items]
Renewal lease term (in years)							5 years
EnerConnex, LLC
Schedule of Equity Method Investments [Line Items]
Equity interest acquired (as a percent)											75.00%		75.00%
Equity interest in acquiree previously held (as a percent)	25.00%			25.00%										25.00%
South Jersey Gas Company
Schedule of Equity Method Investments [Line Items]
Number of counties in which entity operates | county							7
Composite annual rate for all depreciable utility property							2.40%	2.50%	2.20%
Renewal lease term (in years)							5 years
Interest capitalized							$ 2,900,000	$ 5,600,000	$ 4,500,000
Refunds received from third party supplier				$ 10,000,000
Catamaran | Bronx Midco LLC
Schedule of Equity Method Investments [Line Items]
Ownership by parent (as a percent)										99.00%
Catamaran | Annadale
Schedule of Equity Method Investments [Line Items]
Ownership interest (as a percent)											100.00%	100.00%
Marina Energy LLC | Catamaran
Schedule of Equity Method Investments [Line Items]
Ownership by parent (as a percent)										92.00%
Marina Energy LLC | Annadale | Bronx Midco LLC
Schedule of Equity Method Investments [Line Items]
Ownership by parent (as a percent)							92.00%
Marina Energy LLC | Annadale | Annadale
Schedule of Equity Method Investments [Line Items]
Ownership by parent (as a percent)							93.00%				93.00%	93.00%
Marina Energy LLC | Solar Energy Projects Acquisition | Annadale | Bronx Midco LLC
Schedule of Equity Method Investments [Line Items]
Ownership by parent (as a percent)							90.00%
South Jersey Resources Group, LLC
Schedule of Equity Method Investments [Line Items]
Refunds received from third party supplier				11,200,000
Refunds received from third party supplier, amount remaining after remittance								3,900,000
South Jersey Resources Group, LLC | Operating Revenues
Schedule of Equity Method Investments [Line Items]
Refunds received from third party supplier, amount remaining after remittance								3,800,000
South Jersey Resources Group, LLC | Other Income
Schedule of Equity Method Investments [Line Items]
Refunds received from third party supplier, amount remaining after remittance								100,000
Solar Assets
Schedule of Equity Method Investments [Line Items]
Gains (loss) on sale of projects								$ 800,000	3,100,000
Impairment charges									2,400,000
Solar Assets | Minimum
Schedule of Equity Method Investments [Line Items]
Useful life of solar assets (in years)							20 years
Solar Assets | Maximum
Schedule of Equity Method Investments [Line Items]
Useful life of solar assets (in years)							35 years
Marina Energy LLC | Thermal energy generating property and equipment
Schedule of Equity Method Investments [Line Items]
Impairment charges									$ 8,400,000
ETG Utility Operations
Schedule of Equity Method Investments [Line Items]
Number of counties in which entity operates | county							7
Composite annual rate for all depreciable utility property							2.50%	2.30%	2.40%
Minimum annual fee for long-term asset management contract							$ 4,250,000
ETG Utility Operations | South Jersey Resources Group, LLC
Schedule of Equity Method Investments [Line Items]
Refunds received from third party supplier, amount remitted				$ 7,100,000
Elkton Gas | South Jersey Resources Group, LLC
Schedule of Equity Method Investments [Line Items]
Refunds received from third party supplier, amount remitted								$ 200,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations
Schedule of Equity Method Investments [Line Items]
Consideration received on sales or projects								7,200,000	$ 24,300,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | MTF and ACB
Schedule of Equity Method Investments [Line Items]
Consideration received on sales or projects					$ 97,000,000
Gains (loss) on sale of projects								1,100,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Elkton Gas
Schedule of Equity Method Investments [Line Items]
Consideration received on sales or projects	$ 15,600,000
Gains (loss) on sale of projects								$ 700,000