LEASES - ADDITIONAL INFORMATION (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020	Jul. 31, 2021
Lessee, Lease, Description [Line Items]
ROU asset obtained in exchange for operating lease liability	$ 911	$ 46,100
Proceeds from sale leaseback transaction	17,300	0	$ 4,000
ROU asset obtained in exchange for finance lease liability	$ 17,300	$ 0
Weighted average remaining lease term, operating lease	29 years 2 months 12 days	29 years 7 months 6 days
Operating lease, discount rate	3.20%	3.20%
Weighted average remaining lease term, finance lease	4 years	3 years 4 months 24 days
Finance lease, discount rate	2.70%	3.50%
NJNG
Lessee, Lease, Description [Line Items]
Proceeds from sale leaseback transaction	$ 17,300	$ 0	$ 4,000
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	7 years
Meter License | Maximum
Lessee, Lease, Description [Line Items]
Term of contract	10 years
Equipment
Lessee, Lease, Description [Line Items]
Term of contract	7 years
Storage and Capacity
Lessee, Lease, Description [Line Items]
Term of contract	50 years