SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - SOFTWARE COSTS (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023	Sep. 30, 2023
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Capitalized software costs	$ 9,734		$ 9,734		$ 8,375
Operation and maintenance
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Software costs	2,674	$ 3,886	5,927	$ 7,638
Depreciation and amortization
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Software costs	1,265	$ 957	2,254	$ 1,828
Utility plant, at cost
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Software costs	88,234		88,234		51,282
Construction work in progress | Regulated
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Software costs	45,573		45,573		55,012
Nonutility plant and equipment, at cost
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Software costs	344		344		344
Accumulated depreciation and amortization, utility plant
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Accumulated depreciation and amortization	(9,728)		(9,728)		(7,480)
Accumulated depreciation and amortization, nonutility plant and equipment
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Accumulated depreciation and amortization	$ (42)		$ (42)		$ (36)