LOANS RECEIVABLE - Schedule of Loans Receivable (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Sep. 30, 2024	Jun. 30, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, before allowance for credit loss, fee and loan in process	$ 5,786,205	$ 5,748,750
Unaccreted yield adjustments	(1,959)	(15,963)
Loans receivable	5,784,246	5,732,787
Revolving loans, writeoff	0	0
Originated three years before current fiscal year, writeoff	0	3,391
Originated four years before current fiscal year, writeoff	0	464
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, before allowance for credit loss, fee and loan in process	3,970,269	3,945,910
Commercial \| Multi-family mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, before allowance for credit loss, fee and loan in process	2,646,187	2,645,851
Revolving loans, writeoff	0
Originated three years before current fiscal year, writeoff	0
Originated four years before current fiscal year, writeoff	0
Commercial \| Nonresidential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, before allowance for credit loss, fee and loan in process	950,771	948,075
Revolving loans, writeoff	0
Originated three years before current fiscal year, writeoff	0
Originated four years before current fiscal year, writeoff	0
Commercial \| Commercial business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, before allowance for credit loss, fee and loan in process	145,984	142,747
Revolving loans, writeoff	0
Originated three years before current fiscal year, writeoff	0	3,391
Originated four years before current fiscal year, writeoff	0	464
Commercial \| Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, before allowance for credit loss, fee and loan in process	227,327	209,237
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, before allowance for credit loss, fee and loan in process	1,768,230	1,756,051
Revolving loans, writeoff	0
Originated three years before current fiscal year, writeoff	0
Originated four years before current fiscal year, writeoff	0
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, before allowance for credit loss, fee and loan in process	47,706	46,789
Consumer \| Home equity loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, before allowance for credit loss, fee and loan in process	44,741	44,104
Consumer \| Other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, before allowance for credit loss, fee and loan in process	$ 2,965	$ 2,685

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amortized cost, before allowance for credit loss, fee, and loan in process, of financing receivable. Excludes financing receivable covered under loss sharing agreement and net investment in lease.

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Amortized cost excluding accrued interest, before allowance for credit loss, of financing receivable. Excludes net investment in lease.

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Amount, excluding accrued interest, of writeoff of financing receivable that can be withdrawn, repaid, and redrawn.

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Amount, excluding accrued interest, of writeoff of financing receivable originated four years before current fiscal year. Excludes net investment in lease.

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Amount of unamortized loan commitment, origination, and other costs (fees) and purchase premium (discount) on financing receivable recognized as adjustment to yield. Excludes financing receivable covered under loss sharing agreement.

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