EMPLOYEE BENEFIT PLANS - COMPONENTS OF NET PERIODIC COST (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Pension
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 1,381	$ 1,244
Interest cost	3,858	4,060
Expected return on plan assets	(5,925)	(5,087)
Recognized actuarial loss	301	29
Prior service cost (credit) amortization	0	16
Net periodic benefit (credit) cost	(385)	262
OPEB
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	273	642
Interest cost	2,097	2,902
Expected return on plan assets	(2,346)	(1,858)
Recognized actuarial loss	1,793	496
Prior service cost (credit) amortization	(3,270)	0
Net periodic benefit (credit) cost	$ (1,453)	$ 2,182