LEASES - ADDITIONAL INFORMATION (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Sep. 30, 2023	Jul. 31, 2021
Lessee, Lease, Description [Line Items]
ROU asset obtained in exchange for operating lease liability	$ 1,500	$ 100
Proceeds from sale leaseback transactions - natural gas meters	8,814	8,441
ROU asset obtained in exchange for finance lease liability	$ 0
Weighted average remaining lease term, operating lease	29 years 2 months 12 days		29 years 2 months 12 days
Operating lease, discount rate	3.50%		3.50%
Weighted average remaining lease term, finance lease	3 years 7 months 6 days		3 years 3 months 18 days
Finance lease, discount rate	3.30%		2.70%
NJNG
Lessee, Lease, Description [Line Items]
Proceeds from sale leaseback transactions - natural gas meters	$ 8,800	$ 8,400
Solar Property | Minimum
Lessee, Lease, Description [Line Items]
Term of contract	20 years
Renewal term	5 years
Solar Property | Maximum
Lessee, Lease, Description [Line Items]
Term of contract	50 years
Renewal term	20 years
Office Building
Lessee, Lease, Description [Line Items]
Term of contract				16 years
Office Building | Minimum
Lessee, Lease, Description [Line Items]
Term of contract	2 years
Office Building | Maximum
Lessee, Lease, Description [Line Items]
Term of contract	17 years
Meter License | Minimum
Lessee, Lease, Description [Line Items]
Term of contract	6 years
Meter License | Maximum
Lessee, Lease, Description [Line Items]
Term of contract	10 years
Equipment
Lessee, Lease, Description [Line Items]
Term of contract	9 years
Storage and Capacity
Lessee, Lease, Description [Line Items]
Term of contract	50 years