INVESTMENTS IN EQUITY INVESTEES (Details) $ in Thousands		12 Months Ended
	Jan. 30, 2020 phase mi	Sep. 30, 2020 USD ($) mi	Sep. 30, 2019 USD ($)
Schedule of Equity Method Investments [Line Items]
Investments in equity investees		$ 208,375	$ 200,268
Deferred tax gross up		4,600	4,100
Steckman Ridge
Schedule of Equity Method Investments [Line Items]
Investments in equity investees		112,378	114,428
Outstanding principal balance		$ 70,400	70,400
Ownership interest, percent		50.00%
PennEast
Schedule of Equity Method Investments [Line Items]
Investments in equity investees		$ 95,997	$ 85,840
Ownership interest, percent		20.00%
Construction plan, pipeline distance (in miles) | mi	68	120
Number of phases | phase	2
NJR Pipeline | PennEast
Schedule of Equity Method Investments [Line Items]
Ownership interest, percent		20.00%