EMPLOYEE BENEFIT PLANS - COMPONENTS OF NET PERIODIC COST (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other income, net
Pension
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 5,402	$ 8,291	$ 8,730
Interest cost	15,174	9,632	9,112
Expected return on plan assets	(19,972)	(21,275)	(20,150)
Recognized actuarial loss	300	8,745	11,446
Prior service cost (credit) amortization	103	101	102
Net periodic benefit cost recognized as expense	1,007	5,494	9,240
OPEB
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	2,471	4,305	4,844
Interest cost	9,146	6,355	6,071
Expected return on plan assets	(6,721)	(7,575)	(6,497)
Recognized actuarial loss	0	5,684	7,909
Prior service cost (credit) amortization	0	(144)	(179)
Net periodic benefit cost recognized as expense	$ 4,896	$ 8,625	$ 12,148