SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - SOFTWARE COSTS (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Sep. 30, 2024
Oil and Gas, Full Cost Method, Capitalized Cost Excluded from Amortization [Line Items]
Capitalized software costs	$ 10,561		$ 10,522
Operation and maintenance
Oil and Gas, Full Cost Method, Capitalized Cost Excluded from Amortization [Line Items]
Software costs	2,736	$ 3,253
Depreciation and amortization
Oil and Gas, Full Cost Method, Capitalized Cost Excluded from Amortization [Line Items]
Software costs	2,415	$ 990
Utility plant, at cost
Oil and Gas, Full Cost Method, Capitalized Cost Excluded from Amortization [Line Items]
Software costs	133,268		133,158
Construction work in progress | Regulated
Oil and Gas, Full Cost Method, Capitalized Cost Excluded from Amortization [Line Items]
Software costs	34,028		26,659
Nonutility plant and equipment, at cost
Oil and Gas, Full Cost Method, Capitalized Cost Excluded from Amortization [Line Items]
Software costs	344		344
Accumulated depreciation and amortization, utility plant
Oil and Gas, Full Cost Method, Capitalized Cost Excluded from Amortization [Line Items]
Accumulated depreciation and amortization	(16,045)		(13,632)
Accumulated depreciation and amortization, nonutility plant and equipment
Oil and Gas, Full Cost Method, Capitalized Cost Excluded from Amortization [Line Items]
Accumulated depreciation and amortization	$ (50)		$ (48)