SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - SOFTWARE COSTS (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Sep. 30, 2023
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Capitalized software costs	$ 9,105		$ 8,375
Software amortization	100	$ 100
Operation and maintenance
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Software costs	3,253	3,753
Depreciation and amortization
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Software costs	990	$ 871
Utility plant, at cost
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Software costs	51,466		51,282
Construction work in progress | Regulated
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Software costs	69,276		55,012
Nonutility plant and equipment, at cost
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Software costs	344		344
Accumulated depreciation and amortization, utility plant
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Accumulated depreciation and amortization	(8,467)		(7,480)
Accumulated depreciation and amortization, nonutility plant and equipment
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Accumulated depreciation and amortization	$ (39)		$ (36)