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ALLOWANCE FOR CREDIT LOSSES - Allowance for Credit Losses and Balance of Loans Receivable (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Jun. 30, 2025	Sep. 30, 2024	Jun. 30, 2024
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing receivable, allowance for credit loss, excluding accrued interest	$ 45,060	$ 46,191	$ 44,923	$ 44,939
Loans individually analyzed	44,100
Financing receivable, before allowance for credit loss, fee and loan in process	5,767,601	5,814,539
Unaccreted yield adjustments	(182)	(1,602)
Loans receivable	5,767,419	5,812,937
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing receivable, before allowance for credit loss, fee and loan in process	3,961,636	4,012,678
Commercial \| Multi-family mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing receivable, allowance for credit loss, excluding accrued interest	24,644	24,906	24,368	24,125
Financing receivable, before allowance for credit loss, fee and loan in process	2,640,737	2,709,654
Commercial \| Nonresidential mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing receivable, allowance for credit loss, excluding accrued interest	7,690	6,938	6,913	6,125
Financing receivable, before allowance for credit loss, fee and loan in process	988,969	986,556
Commercial \| Commercial business
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing receivable, allowance for credit loss, excluding accrued interest	1,718	2,428	1,705	1,573
Financing receivable, before allowance for credit loss, fee and loan in process	142,304	138,755
Commercial \| Construction
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing receivable, allowance for credit loss, excluding accrued interest	1,339	1,155	1,503	1,230
Financing receivable, before allowance for credit loss, fee and loan in process	189,626	177,713
Residential
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing receivable, allowance for credit loss, excluding accrued interest	9,148	10,180	9,985	11,461
Financing receivable, before allowance for credit loss, fee and loan in process	1,749,362	1,748,591
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing receivable, before allowance for credit loss, fee and loan in process	56,603	53,270
Consumer \| Home equity loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing receivable, allowance for credit loss, excluding accrued interest	419	490	357	349
Financing receivable, before allowance for credit loss, fee and loan in process	54,116	50,737
Consumer \| Other consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing receivable, allowance for credit loss, excluding accrued interest	102	94	$ 92	$ 76
Financing receivable, before allowance for credit loss, fee and loan in process	2,487	2,533
Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Allowance for Credit Losses [Line Items]
Related Allowance	2	45
Loans acquired with deteriorated credit quality collectively evaluated	115	130
Loans individually analyzed	811	875
Loans collectively evaluated	11,270	11,784
Receivables Acquired with Deteriorated Credit Quality \| Commercial \| Multi-family mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Related Allowance	0	0
Loans acquired with deteriorated credit quality collectively evaluated	0	0
Loans individually analyzed	0	0
Loans collectively evaluated	0	0
Receivables Acquired with Deteriorated Credit Quality \| Commercial \| Nonresidential mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Related Allowance	0	0
Loans acquired with deteriorated credit quality collectively evaluated	18	20
Loans individually analyzed	230	240
Loans collectively evaluated	1,238	1,405
Receivables Acquired with Deteriorated Credit Quality \| Commercial \| Commercial business
Financing Receivable, Allowance for Credit Losses [Line Items]
Related Allowance	0	0
Loans acquired with deteriorated credit quality collectively evaluated	14	23
Loans individually analyzed	0	0
Loans collectively evaluated	791	1,093
Receivables Acquired with Deteriorated Credit Quality \| Commercial \| Construction
Financing Receivable, Allowance for Credit Losses [Line Items]
Related Allowance	0	0
Loans acquired with deteriorated credit quality collectively evaluated	0	0
Loans individually analyzed	0	0
Loans collectively evaluated	5,735	5,735
Receivables Acquired with Deteriorated Credit Quality \| Residential
Financing Receivable, Allowance for Credit Losses [Line Items]
Related Allowance	2	34
Loans acquired with deteriorated credit quality collectively evaluated	83	87
Loans individually analyzed	571	614
Loans collectively evaluated	3,506	3,551
Receivables Acquired with Deteriorated Credit Quality \| Consumer \| Home equity loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Related Allowance	0	11
Loans acquired with deteriorated credit quality collectively evaluated	0	0
Loans individually analyzed	10	21
Loans collectively evaluated	0	0
Receivables Acquired with Deteriorated Credit Quality \| Consumer \| Other consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Related Allowance	0	0
Loans acquired with deteriorated credit quality collectively evaluated	0	0
Loans individually analyzed	0	0
Loans collectively evaluated	0	0
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Losses [Line Items]
Related Allowance	1,169	2,440
Loans acquired with deteriorated credit quality collectively evaluated	43,774	43,576
Loans individually analyzed	43,274	44,722
Loans collectively evaluated	5,712,246	5,757,158
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration \| Commercial \| Multi-family mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Related Allowance	1,023	1,377
Loans acquired with deteriorated credit quality collectively evaluated	23,621	23,529
Loans individually analyzed	31,615	30,857
Loans collectively evaluated	2,609,122	2,678,797
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration \| Commercial \| Nonresidential mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Related Allowance	0	0
Loans acquired with deteriorated credit quality collectively evaluated	7,672	6,918
Loans individually analyzed	5,502	5,523
Loans collectively evaluated	981,999	979,388
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration \| Commercial \| Commercial business
Financing Receivable, Allowance for Credit Losses [Line Items]
Related Allowance	84	971
Loans acquired with deteriorated credit quality collectively evaluated	1,620	1,434
Loans individually analyzed	1,139	2,223
Loans collectively evaluated	140,374	135,439
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration \| Commercial \| Construction
Financing Receivable, Allowance for Credit Losses [Line Items]
Related Allowance	0	0
Loans acquired with deteriorated credit quality collectively evaluated	1,339	1,155
Loans individually analyzed	0	0
Loans collectively evaluated	183,891	171,978
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration \| Residential
Financing Receivable, Allowance for Credit Losses [Line Items]
Related Allowance	59	60
Loans acquired with deteriorated credit quality collectively evaluated	9,004	9,999
Loans individually analyzed	4,730	5,936
Loans collectively evaluated	1,740,555	1,738,490
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration \| Consumer \| Home equity loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Related Allowance	3	32
Loans acquired with deteriorated credit quality collectively evaluated	416	447
Loans individually analyzed	288	183
Loans collectively evaluated	53,818	50,533
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration \| Consumer \| Other consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Related Allowance	0	0
Loans acquired with deteriorated credit quality collectively evaluated	102	94
Loans individually analyzed	0	0
Loans collectively evaluated	$ 2,487	$ 2,533