SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - SOFTWARE COSTS (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Sep. 30, 2023
Oil and Gas, Full Cost Method, Capitalized Cost Excluded from Amortization [Line Items]
Capitalized software costs	$ 10,254		$ 10,254		$ 8,375
Operation and maintenance
Oil and Gas, Full Cost Method, Capitalized Cost Excluded from Amortization [Line Items]
Software costs	4,048	$ 3,163	9,975	$ 10,801
Depreciation and amortization
Oil and Gas, Full Cost Method, Capitalized Cost Excluded from Amortization [Line Items]
Software costs	1,507	$ 1,320	3,761	$ 3,148
Utility plant, at cost
Oil and Gas, Full Cost Method, Capitalized Cost Excluded from Amortization [Line Items]
Software costs	88,128		88,128		51,282
Construction work in progress | Regulated
Oil and Gas, Full Cost Method, Capitalized Cost Excluded from Amortization [Line Items]
Software costs	62,527		62,527		55,012
Nonutility plant and equipment, at cost
Oil and Gas, Full Cost Method, Capitalized Cost Excluded from Amortization [Line Items]
Software costs	344		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	(11,232)		(11,232)		(7,480)
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	$ (45)		$ (45)		$ (36)