FAIR VALUE MEASUREMENTS - Additional information (Details) - USD ($)	12 Months Ended	24 Months Ended
Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2023	Sep. 30, 2019
FAIR VALUE MEASUREMENTS
Fair Value, Net Derivative Asset (Liability), Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]				Fees and Commissions, Mortgage Banking and Servicing
Unrealized gains recognized in earnings	$ 268,000,000	$ 238,000
Derivative assets and liabilities held at the balance sheet date	268,000	(238,000)	$ 1,567,000	$ 268,000	$ 14,937,000
Impairment charges on nonresidential mortgage loan servicing rights	$ 0	$ 0	$ 0

The amount of impairment charges on nonresidential mortgage loan servicing rights.

No definition available.

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- References

No definition available.

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- Definition

Amount of gain (loss) recognized in income from derivative asset (liability) after deduction of derivative liability (asset), 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

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-3

+ Details

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- Definition

Fair value of financial instrument classified as derivative asset (liability) after deduction of derivative liability (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 (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-SubTopic 10
-Topic 820
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-3

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- Definition

Indicates line item in statement in which net income is reported that includes gain (loss) from derivative asset (liability) after deduction of derivative liability (asset), measured at fair value using unobservable input (level 3).

+ References

+ Details

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