RETIREMENT PLANS (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Other disclosures
Net actuarial gains arising during the period	$ 0	$ 880
Reduction in unrecognized benefit costs previously included in AOCL	(33)	(60)
Curtailment gain, net of taxes of $0	0	1,699
Pension Plan
Net periodic benefit cost:
Service cost	0	50
Interest cost	65	83
Expected return on plan assets	(137)	(163)
Amortization of prior service cost (credit)	0	1
Amortization of net actuarial loss	10	35
Curtailment cost (income)	0	53
Net periodic benefit (income) cost	(62)	59
Other disclosures
Estimated future Pension Plan contributions	0
SERP
Net periodic benefit cost:
Service cost	0	3
Interest cost	13	18
Expected return on plan assets	0	0
Amortization of prior service cost (credit)	0	(1)
Amortization of net actuarial loss	0	5
Curtailment cost (income)	0	(53)
Net periodic benefit (income) cost	13	(28)
Postretirement Medical
Net periodic benefit cost:
Service cost	0	0
Interest cost	18	20
Expected return on plan assets	0	0
Amortization of prior service cost (credit)	0	0
Amortization of net actuarial loss	23	20
Curtailment cost (income)	0	0
Net periodic benefit (income) cost	$ 41	40
Pension Plan and SERP
Other disclosures
Net actuarial gains arising during the period		880
Reduction in unrecognized benefit costs previously included in AOCL		1,699
Curtailment gain, net of taxes of $0		$ 1,699