RETIREMENT PLANS (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended			6 Months Ended
	Apr. 30, 2021	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2021	Mar. 31, 2020
Other disclosures
Net actuarial gains arising during the period		$ 0	$ 0		$ 0	$ 880
Reduction in unrecognized benefit costs previously included in AOCI		(33)	(20)		(66)	(80)
Curtailment gain		0	0		0	1,699
Pension Plan
Net periodic benefit cost:
Service cost					0	50
Interest cost		64	72		129	155
Expected return on plan assets		(137)	(172)		(274)	(335)
Amortization of prior service cost (credit)					0	1
Amortization of net actuarial loss		10	0		20	35
Curtailment cost (income)					0	53
Net periodic benefit (income) cost		(63)	(100)		(125)	(41)
Other disclosures
Estimated future Pension Plan contributions		0			0
SERP
Net periodic benefit cost:
Service cost					0	3
Interest cost		13	15		26	33
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	15		26	(13)
Postretirement Medical
Net periodic benefit cost:
Service cost					0	0
Interest cost		18	20		36	40
Amortization of prior service cost (credit)					0	0
Amortization of net actuarial loss		23	20		46	40
Curtailment cost (income)					0	0
Net periodic benefit (income) cost		$ 41	$ 40		$ 82	$ 80
Postretirement Medical | Subsequent Event
Other disclosures
Curtailment gain	$ 2,000
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				$ 1,699