NATURE OF THE BUSINESS (Details)		12 Months Ended
	Jun. 01, 2018 MW	Sep. 30, 2018 subsidiary customer
Natural Gas Distribution
Investment [Line Items]
Total retail customers (in customers) | customer		538,700
NJR Retail Holdings Corporation
Investment [Line Items]
Number of principal subsidiaries (in subsidiaries) | subsidiary		2
Steckman Ridge
Investment [Line Items]
Ownership interest, percent		50.00%
PennEast
Investment [Line Items]
Ownership interest, percent		20.00%
Clean Energy Ventures
Investment [Line Items]
Wind farm total capacity (in MW) | MW	9.7