RELATED PARTY TRANSACTIONS - ADDITIONAL INFORMATION (Details) $ in Millions		6 Months Ended
	Apr. 01, 2020 USD ($) Bcf	Mar. 31, 2024 dth / d numberOfAgreement agreement Bcf
Related Party Transaction [Line Items]
Number of asset management agreements | agreement		1
NJNG to NJRES Affiliate
Related Party Transaction [Line Items]
Asset management agreement, period	5 years
NJNG to Steckman RIdge Affiliate
Related Party Transaction [Line Items]
Natural gas sold at cost under asset management agreement (in Bcf) | Bcf	3
Approximate annual demand fees under agreement | $	$ 9.3
NJNG to Adelphia Affiliate
Related Party Transaction [Line Items]
Number of transportation agreements | numberOfAgreement		2
NJNG to Adelphia Affiliate | Transportation Precedent Agreement One
Related Party Transaction [Line Items]
Transportation capacity under precedent agreement (in bcf per day) | dth / d		130,000
Transportation precedent agreement term		5 years
NJNG to Adelphia Affiliate | Transportation Precedent Agreement Two
Related Party Transaction [Line Items]
Transportation capacity under precedent agreement (in bcf per day) | dth / d		130,000
Transportation precedent agreement term		15 years
Leaf River Energy Center LLC
Related Party Transaction [Line Items]
Natural gas sold at cost under asset management agreement (in Bcf) | Bcf		3
Storage capacity agreement term		5 years
NJNG and Clean Energy Ventures to PPA | Sublease Agreement One
Related Party Transaction [Line Items]
Sublease agreement term		15 years
NJNG and Clean Energy Ventures to PPA | Sublease Agreement Two
Related Party Transaction [Line Items]
Sublease agreement term		20 years
NJNG To NJR Subsidiaries
Related Party Transaction [Line Items]
Term of contract		16 years