ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2021	Mar. 31, 2020	Sep. 30, 2020
Changes in foreign currency translation
Beginning accumulated foreign currency translation	$ 311	$ 696	$ 691	$ 545	$ 691
Change in cumulative translation adjustment before reclassifications	(85)	84		(319)	89
Income taxes	0	0		0	0
Net current period other comprehensive (loss) income	(85)	84		(319)	89
Ending accumulated foreign currency translation	226	780	696	226	780
Changes in retirement plans
Beginning accumulated retirement plans benefit cost	(1,947)	(969)	(3,608)	(1,980)	(3,608)
Amortization of net actuarial loss and prior service cost	33	20		66	80
Net actuarial gains arising during the period	0	0		0	2,579
Income taxes	0	0		0	0
Net current period other comprehensive income	33	20		66	2,659
Ending accumulated retirement plans benefit cost	(1,914)	(949)	$ (969)	(1,914)	(949)
Accumulated other comprehensive loss, net of taxes	$ (1,688)	$ (169)		$ (1,688)	$ (169)	$ (1,435)