For each balance sheet presented, the amount of accumulated amortization for capitalized computer software costs.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 350
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 985
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Amount before accumulated amortization of capitalized costs for computer software, including but not limited to, acquired and internally developed computer software.

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The carrying amount of capitalized computer software costs net of accumulated amortization as of the balance sheet date.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 985
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
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Amount of increase (decrease) in capitalized computer software costs.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 932
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - SOFTWARE COSTS (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2026	Mar. 31, 2025	Sep. 30, 2025
Oil and Gas, Full Cost Method, Capitalized Cost Excluded from Amortization [Line Items]
Capitalized software costs	$ 11,195		$ 11,195		$ 11,151
Operation and maintenance
Oil and Gas, Full Cost Method, Capitalized Cost Excluded from Amortization [Line Items]
Software costs	323	$ 1,151	516	$ 3,887
Depreciation and amortization
Oil and Gas, Full Cost Method, Capitalized Cost Excluded from Amortization [Line Items]
Software costs	3,130	$ 3,128	6,527	$ 5,543
Utility plant, at cost
Oil and Gas, Full Cost Method, Capitalized Cost Excluded from Amortization [Line Items]
Software costs	134,817		134,817		132,868
Construction work in progress \| Regulated
Oil and Gas, Full Cost Method, Capitalized Cost Excluded from Amortization [Line Items]
Software costs	109,174		109,174		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		344
Accumulated depreciation and amortization, utility plant
Oil and Gas, Full Cost Method, Capitalized Cost Excluded from Amortization [Line Items]
Accumulated depreciation and amortization	(31,418)		(31,418)		(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	$ (85)		$ (85)		$ (70)