COMMITMENTS AND CONTINGENT LIABILITIES - LEGAL PROCEEDINGS (Details) - USD ($) $ in Thousands				1 Months Ended			12 Months Ended
	Sep. 11, 2023	Apr. 12, 2023	Apr. 07, 2021	Sep. 30, 2022	Mar. 31, 2022	Apr. 30, 2021	Sep. 30, 2023
Loss Contingencies [Line Items]
Manufactured gas plant remediation				$ 127,060			$ 169,390
Recovery from third party of environmental remediation cost, period							7 years
Regulatory assets				500,666			$ 584,830
Expended, net of recoveries
Loss Contingencies [Line Items]
Regulatory assets							66,300
RAC
Loss Contingencies [Line Items]
Approved rate, amount		$ 15,400	$ 11,100		$ 11,700
Approved rate increase (decrease), amount	$ 2,400	$ 3,700		$ 3,800	$ 600	$ 1,300
Minimum
Loss Contingencies [Line Items]
Product liability contingency, loss exposure in excess of accrual, best estimate							137,300
Maximum
Loss Contingencies [Line Items]
Product liability contingency, loss exposure in excess of accrual, best estimate							$ 201,500