SHAREHOLDERS' EQUITY - Components of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Sep. 30, 2023
After-tax amounts:
Unrealized pension actuarial loss	$ (8,499)	$ (7,981)
Unrealized pension actuarial loss
Pre-tax amounts:
Unrealized pension actuarial loss	(9,886)	(10,407)
After-tax amounts:
Unrealized pension actuarial loss	(7,579)	(7,981)
Unrealized loss on available-for-sale debt security
Pre-tax amounts:
Unrealized pension actuarial loss	(1,191)	0
After-tax amounts:
Unrealized pension actuarial loss	(920)	0
Accumulated Other Comprehensive Income (Loss)
Pre-tax amounts:
Unrealized pension actuarial loss	(11,077)	(10,407)
After-tax amounts:
Unrealized pension actuarial loss	$ (8,499)	$ (7,981)

Amount, after tax, of accumulated increase (decrease) in equity from transaction and other event and circumstance from nonowner source.

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-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant