NATURE OF THE BUSINESS (Details)	6 Months Ended
	Mar. 31, 2019 subsidiary customer
Steckman Ridge
Nature of Business [Line Items]
Ownership percentage	50.00%
PennEast
Nature of Business [Line Items]
Ownership percentage	20.00%
Natural Gas Distribution
Nature of Business [Line Items]
Total retail customers | customer	546,100
NJR Retail Holdings Corporation
Nature of Business [Line Items]
Number of principal subsidiaries | subsidiary	2