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LEASES - ADDITIONAL INFORMATION (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2026	Mar. 31, 2025	Sep. 30, 2025	Jul. 31, 2021
Lessee, Lease, Description [Line Items]
ROU asset obtained in exchange for operating lease liability	$ 0.8	$ 5.5	$ 5.4	$ 5.5
ROU asset obtained in exchange for finance lease liability	$ 0.0			$ 0.0
Weighted average remaining lease term, operating lease	28 years		28 years		28 years 4 months 24 days
Operating lease, discount rate, percentage	4.10%		4.10%		4.00%
Weighted average remaining lease term, finance lease	2 years 1 month 6 days		2 years 1 month 6 days		2 years 4 months 24 days
Finance lease, discount rate, percentage	3.40%		3.40%		3.40%
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	11 years		11 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	10 years		10 years
Storage and Capacity
Lessee, Lease, Description [Line Items]
Term of contract	50 years		50 years