RETIREMENT PLANS (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2021	Jun. 30, 2020
Other disclosures
Net actuarial gains arising during the period	$ 0	$ 0		$ 0	$ 880
Reduction in unrecognized benefit costs previously included in AOCI	(26)	(20)		(92)	(100)
Curtailment gain and gain on termination of post-retirement medical plan in OCI	541			541	1,699
Gain on termination of post-retirement medical plan	2,341	0		2,341	0
Pension Plan
Net periodic benefit cost:
Service cost				0	50
Interest cost	64	73		193	228
Expected return on plan assets	(136)	(173)		(410)	(508)
Amortization of prior service cost (credit)				0	1
Amortization of net actuarial loss	10	0		30	35
Curtailment cost (income)				0	53
Net periodic benefit (income) cost	(62)	(100)		(187)	(141)
Other disclosures
Estimated future Pension Plan contributions	0			0
SERP
Net periodic benefit cost:
Service cost				0	3
Interest cost	13	16		39	49
Amortization of prior service cost (credit)				0	(1)
Amortization of net actuarial loss	0	0		0	5
Curtailment cost (income)				0	(53)
Net periodic benefit (income) cost	13	16		39	3
Post-retirement Medical
Net periodic benefit cost:
Service cost				0	0
Interest cost	12	20		48	60
Amortization of prior service cost (credit)				0	0
Amortization of net actuarial loss	16	20		62	60
Curtailment cost (income)				0	0
Net periodic benefit (income) cost	28	40		110	120
Other disclosures
Curtailment gain and gain on termination of post-retirement medical plan in OCI	541	0		541	0
Gain on termination of post-retirement medical plan	2,341			2,341
Pension Plan And SERP
Other disclosures
Net actuarial gains arising during the period			$ 880
Reduction in unrecognized benefit costs previously included in AOCI			1,699
Curtailment gain and gain on termination of post-retirement medical plan in OCI	$ 0	$ 0	$ 1,699	$ 0	$ 1,699