FAIR VALUE MEASUREMENT OF FINANCIAL INSTRUMENTS - Reconciliation of Changes in Fair Value of Financial Assets and Liabilities Classified as Level 3 (Details) - Level 3 - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Reconciliation of changes in the fair value of our financial liabilities
Liabilities at beginning of period	$ 8,350	$ 3,780	$ 9,455	$ 4,022
Additions	0	0	0	500
Total gains or losses included in earnings	5,650	1,750	5,670	1,758
Settlements	0	(500)	(1,125)	(1,250)
Liabilities at end of period	14,000	5,030	14,000	5,030
Debt Securities
Reconciliation of changes in the fair value of our financial assets
Assets at beginning of period	37,868	33,107	37,440	33,565
Purchases	250	2,033	250	2,075
Accrued interest	433	0	866	0
Transfers out	0	0	0	(500)
Reserves	0	0	(5)	0
Assets at end of period	38,551	35,140	38,551	35,140
Equity Securities Without Readily Determinable Fair Value
Reconciliation of changes in the fair value of our financial assets
Assets at beginning of period	28,523	25,800	28,232	23,745
Purchases	2,245	501	2,536	2,556
Disposals	(616)	0	(616)	0
Assets at end of period	$ 30,152	$ 26,301	$ 30,152	$ 26,301

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis Accrued Interest

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Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Reserves

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Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers In (Out)

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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- Definition

Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

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Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-SubTopic 10
-Topic 820
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

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- Definition

Amount of gain (loss) recognized in income from liability measured at fair value on recurring basis using unobservable input (level 3).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

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Amount of purchases of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of settlements of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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