ALLOWANCE FOR CREDIT LOSSES - Changes in the Allowance for Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Sep. 30, 2024	Sep. 30, 2023	Jun. 30, 2024
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 44,939	$ 48,734	$ 48,734
Charge-offs	(129)	(2,222)	(10,276)
Recoveries	5	115
Provision for (reversal of) credit losses	108	245
Ending balance	44,923	46,872	44,939
Commercial \| Multi-family mortgage
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	24,125	26,362	26,362
Charge-offs	0	0	(398)
Recoveries	0	0
Provision for (reversal of) credit losses	243	(772)
Ending balance	24,368	25,590	24,125
Commercial \| Nonresidential mortgage
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	6,125	8,953	8,953
Charge-offs	0	(2,033)	(5,975)
Recoveries	0	109
Provision for (reversal of) credit losses	788	408
Ending balance	6,913	7,437	6,125
Commercial \| Commercial business
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	1,573	1,440	1,440
Charge-offs	(127)	(189)	(3,866)
Recoveries	5	6
Provision for (reversal of) credit losses	254	156
Ending balance	1,705	1,413	1,573
Commercial \| Construction
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	1,230	1,336	1,336
Charge-offs	0	0
Recoveries	0	0
Provision for (reversal of) credit losses	273	(19)
Ending balance	1,503	1,317	1,230
Residential
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	11,461	10,237	10,237
Charge-offs	(2)	0	(37)
Recoveries	0	0
Provision for (reversal of) credit losses	(1,474)	466
Ending balance	9,985	10,703	11,461
Consumer \| Home equity loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	349	338	338
Charge-offs	0	0
Recoveries	0	0
Provision for (reversal of) credit losses	8	4
Ending balance	357	342	349
Consumer \| Other consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	76	68	68
Charge-offs	0	0
Recoveries	0	0
Provision for (reversal of) credit losses	16	2
Ending balance	$ 92	$ 70	$ 76

Amount excluding accrued interest, of allowance for credit loss on financing receivable. Excludes net investment in lease.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

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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.

+ References

No definition available.

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- Definition

Amount, excluding accrued interest, of increase in allowance for credit loss on financing receivable from recovery. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

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- Definition

Amount, excluding accrued interest, of decrease in allowance for credit loss on financing receivable from writeoff. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

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- Definition

Amount, excluding accrued interest, of credit loss expense (reversal of expense) on financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

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