EMPLOYEE BENEFIT PLANS - COMPONENTS OF NET PERIODIC COST (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Pension
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 1,244	$ 1,350
Interest cost	4,060	3,794
Expected return on plan assets	(5,087)	(4,993)
Recognized actuarial loss	29	75
Prior service cost amortization	16	25
Net periodic benefit cost	262	251
OPEB
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	642	618
Interest cost	2,902	2,286
Expected return on plan assets	(1,858)	(1,680)
Recognized actuarial loss	496	0
Prior service cost amortization	0	0
Net periodic benefit cost	$ 2,182	$ 1,224