SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - SOFTWARE COSTS (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Sep. 30, 2025
Oil and Gas, Full Cost Method, Capitalized Cost Excluded from Amortization [Line Items]
Capitalized software costs	$ 11,159		$ 11,151
Operation and maintenance
Oil and Gas, Full Cost Method, Capitalized Cost Excluded from Amortization [Line Items]
Software costs	193	$ 2,736
Depreciation and amortization
Oil and Gas, Full Cost Method, Capitalized Cost Excluded from Amortization [Line Items]
Software costs	3,397	$ 2,415
Utility plant, at cost
Oil and Gas, Full Cost Method, Capitalized Cost Excluded from Amortization [Line Items]
Software costs	134,784		132,868
Construction work in progress | Regulated
Oil and Gas, Full Cost Method, Capitalized Cost Excluded from Amortization [Line Items]
Software costs	91,819		87,274
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	(28,296)		(24,906)
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	$ (77)		$ (70)