INVESTMENTS IN EQUITY INVESTEES (Details) $ in Thousands		9 Months Ended	12 Months Ended
Jan. 30, 2020 phase mi	Jun. 30, 2020 USD ($) mi	Sep. 30, 2019 USD ($)
Schedule of Equity Method Investments [Line Items]
Investments in equity investees		$ 205,800	$ 200,268
Deferred tax gross up		$ 4,600	4,100
PennEast \| NJR Pipeline
Schedule of Equity Method Investments [Line Items]
Ownership percentage		20.00%
Steckman Ridge
Schedule of Equity Method Investments [Line Items]
Investments in equity investees		$ 112,909	114,428
Total outstanding principal balance of loans		$ 70,400	70,400
Ownership percentage		50.00%
PennEast
Schedule of Equity Method Investments [Line Items]
Investments in equity investees		$ 92,891	$ 85,840
Ownership percentage		20.00%
Construction plan, project area (in miles) \| mi	68	120
Number of phases \| phase	2

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