RELATED PARTY TRANSACTIONS - ADDITIONAL INFORMATION (Details) $ in Millions		1 Months Ended		9 Months Ended
	Apr. 01, 2020 USD ($) Bcf	Jun. 30, 2022	Mar. 31, 2021	Jun. 30, 2023 lease dth / d Bcf	Jul. 31, 2021
Related Party Transaction [Line Items]
Number of asset management agreements | lease				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]
Transportation capacity under precedent agreement with PennEast (in bcf per day) | dth / d				130,000
NJNG to Adelphia Affiliate | Transportation Precedent Agreement One
Related Party Transaction [Line Items]
Transportation precedent agreement term				5 years
NJNG to Adelphia Affiliate | Transportation Precedent Agreement Two
Related Party Transaction [Line Items]
Transportation precedent agreement term				15 years
Transportation capacity under precedent agreement with PennEast (in bcf per day) | dth / d				130,000
Right to reduction term				7 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
Related Party Transaction [Line Items]
Sublease agreement term		20 years	15 years
NJNG To NJR Subsidiaries
Related Party Transaction [Line Items]
Term of contract					16 years