COMMITMENTS AND CONTINGENT LIABILITIES - LEGAL PROCEEDINGS (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Loss Contingencies [Line Items]
Manufactured gas plant remediation	$ 166,990	$ 161,650
Recovery from third party of environmental remediation cost, period	7 years
Regulatory assets	$ 672,518	$ 609,192
Expended, net of recoveries
Loss Contingencies [Line Items]
Regulatory assets	75,000
Minimum
Loss Contingencies [Line Items]
Product liability contingency, loss exposure in excess of accrual, best estimate	144,300
Maximum
Loss Contingencies [Line Items]
Product liability contingency, loss exposure in excess of accrual, best estimate	$ 200,200