LEASES - ADDITIONAL INFORMATION (Details) - USD ($)	3 Months Ended		9 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Sep. 30, 2021	Jul. 31, 2021
Lessee, Lease, Description [Line Items]
ROU asset obtained in exchange for operating lease liability	$ 87,000	$ 0	$ 911,000	$ 12,800,000
Proceeds from sale leaseback transactions			$ 17,300,000	0
ROU asset obtained in exchange for finance lease liability	$ 0	$ 0		0
Weighted average remaining lease term, operating lease	29 years 4 months 24 days		29 years 4 months 24 days		29 years 7 months 6 days
Operating lease, discount rate	3.20%		3.20%		3.20%
Weighted average remaining lease term, finance lease	4 years 2 months 12 days		4 years 2 months 12 days		3 years 4 months 24 days
Finance lease, discount rate	2.70%		2.70%		3.50%
NJNG
Lessee, Lease, Description [Line Items]
Proceeds from sale leaseback transactions			$ 17,300,000	$ 0
Solar Property | Minimum
Lessee, Lease, Description [Line Items]
Term of contract	20 years		20 years
Renewal term	5 years		5 years
Solar Property | Maximum
Lessee, Lease, Description [Line Items]
Term of contract	50 years		50 years
Renewal term	20 years		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		2 years
Office Building | Maximum
Lessee, Lease, Description [Line Items]
Term of contract	17 years		17 years
Meter License | Minimum
Lessee, Lease, Description [Line Items]
Term of contract	7 years		7 years
Meter License | Maximum
Lessee, Lease, Description [Line Items]
Term of contract	10 years		10 years
Equipment
Lessee, Lease, Description [Line Items]
Term of contract	6 years		6 years
Storage and Capacity
Lessee, Lease, Description [Line Items]
Term of contract	50 years		50 years