EMPLOYEE BENEFIT PLANS - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Components of the net periodic pension expense (benefit)
Interest cost	$ 753	$ 1,097	$ 1,506	$ 2,194
Expected return on plan assets	(967)	(1,381)	(1,934)	(2,762)
Recognized net actuarial loss	590	669	1,180	1,338
Settlement	398	0	1,413	0
Net pension expense	$ 774	$ 385	$ 2,165	$ 770