COMMITMENTS AND CONTINGENT LIABILITIES - LEGAL PROCEEDINGS (Details) - USD ($) $ in Thousands	9 Months Ended
Jun. 30, 2025	Sep. 30, 2024
Site Contingency [Line Items]
Manufactured gas plant remediation	$ 155,861	$ 161,650
Recovery from third party of environmental remediation cost, period	7 years
Regulatory assets	$ 615,859	$ 609,192
Expended, net of recoveries
Site Contingency [Line Items]
Regulatory assets	70,500
Minimum
Site Contingency [Line Items]
Product liability contingency, loss exposure in excess of accrual, best estimate	130,900
Maximum
Site Contingency [Line Items]
Product liability contingency, loss exposure in excess of accrual, best estimate	$ 194,600

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Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are not expected to be recovered through revenue sources within one year or the normal operating cycle if longer.

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