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Investments in parties associated with the reporting entity net of guarantees to be paid by the reporting entity (which are included as liabilities on the balance sheet).

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This item represents an other than temporary decline in value that has been recognized against an investment accounted for under the equity method of accounting. The excess of the carrying amount over the fair value of the investment represents the amount of the write down which is or was reflected in earnings. The written down value is a new cost basis with the adjusted value of the investment becoming its new carrying value subject to the equity accounting method. Evidence of a loss in value might include, but would not necessarily be limited to, absence of an ability to recover the carrying amount of the investment or inability of the investee to sustain an earnings capacity which would justify the carrying amount of the investment.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

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Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

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AFFILIATIONS, DISCONTINUED OPERATIONS AND RELATED-PARTY TRANSACTIONS - Narrative (Details) - USD ($)		1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended
	Feb. 20, 2020	Dec. 31, 2019	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Impairment charges			$ 87,400,000		$ 87,400,000
Investment			32,509,000		32,509,000		$ 106,230,000
Investments in unconsolidated affiliates					(16,800,000)	$ 2,000,000.0
Notes receivable - affiliate			40,100,000		40,100,000		33,900,000
Net asset - included in investment in affiliates and other noncurrent liabilities			$ 32,500,000		32,500,000		106,200,000
Combined equity contributions and the notes receivable - affiliate					$ 72,600,000		140,100,000
PennEast Pipeline Company, LLC (PennEast)
Schedule of Equity Method Investments [Line Items]
Equity interest (as a percent)			20.00%		20.00%
Contract extension to construct pipeline (in years)	2 years	2 years
Investment			$ 8,000,000.0		$ 8,000,000.0		91,300,000
Energenic US LLC
Schedule of Equity Method Investments [Line Items]
Equity interest (as a percent)			50.00%		50.00%
Investment			$ 0		$ 0
Millennium Account Services, LLC
Schedule of Equity Method Investments [Line Items]
Equity interest (as a percent)			50.00%		50.00%
Potato Creek, LLC (Potato Creek)
Schedule of Equity Method Investments [Line Items]
Equity interest (as a percent)			30.00%		30.00%
REV \| Equity Method Investee
Schedule of Equity Method Investments [Line Items]
Related party notes receivable			$ 26,900,000		$ 26,900,000		19,300,000
Secured Debt
Schedule of Equity Method Investments [Line Items]
Related party notes receivable			$ 11,600,000		$ 11,600,000		$ 12,100,000
Interest rate			7.50%		7.50%		7.50%
Unsecured promissory notes
Schedule of Equity Method Investments [Line Items]
Notes receivable - affiliate			$ 1,600,000		$ 1,600,000		$ 2,500,000
South Jersey Energy Company \| EnergyMark
Schedule of Equity Method Investments [Line Items]
Equity interest (as a percent)			33.00%		33.00%
South Jersey Energy Company \| REV
Schedule of Equity Method Investments [Line Items]
Equity interest (as a percent)			35.00%		35.00%
SJRG \| EnergyMark
Schedule of Equity Method Investments [Line Items]
Total operating revenue, affiliates			$ 3,500,000	$ 3,500,000	$ 10,900,000	$ 8,700,000