COMMITMENTS AND CONTINGENT LIABILITIES - LEGAL PROCEEDINGS (Details) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2024	Sep. 30, 2023
Site Contingency [Line Items]
Manufactured gas plant remediation	$ 153,818	$ 169,390
Recovery from third party of environmental remediation cost, period	7 years
Regulatory assets	$ 557,280	$ 584,830
Expended, net of recoveries
Site Contingency [Line Items]
Regulatory assets	74,300
Minimum
Site Contingency [Line Items]
Product liability contingency, loss exposure in excess of accrual, best estimate	139,700
Maximum
Site Contingency [Line Items]
Product liability contingency, loss exposure in excess of accrual, best estimate	$ 203,900