EMPLOYEE BENEFIT PLANS - COMPONENTS OF NET PERIODIC COST (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Pension
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 1,245	$ 1,381
Interest cost	3,964	3,858
Expected return on plan assets	(6,137)	(5,925)
Recognized actuarial loss	38	301
Prior service cost (credit) amortization	0	0
Net periodic benefit (credit) cost	(890)	(385)
OPEB
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	272	273
Interest cost	2,698	2,097
Expected return on plan assets	(2,259)	(2,346)
Recognized actuarial loss	2,796	1,793
Prior service cost (credit) amortization	(3,270)	(3,270)
Net periodic benefit (credit) cost	$ 237	$ (1,453)