Loans Receivable - Non-accrual Loans and Loans 90 Days or More Past Due and Accruing (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Sep. 30, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual percent of total loans	0.28%	0.33%
Financial Asset Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual	$ 59,886	$ 69,541
Non-accrual with no ACL	0	0
90 days or more past due and accruing	0	1,083
Financial Asset Originated \| Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual	39,797	46,299
Non-accrual with no ACL	0	0
90 days or more past due and accruing	0	1,083
Financial Asset Originated \| Commercial loans \| Multi-family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual	10,477	18,743
Non-accrual with no ACL	0	0
90 days or more past due and accruing	0	0
Financial Asset Originated \| Commercial loans \| Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual	29,320	26,362
Non-accrual with no ACL	0	0
90 days or more past due and accruing	0	0
Financial Asset Originated \| Commercial loans \| Commercial & industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual	0	0
Non-accrual with no ACL	0	0
90 days or more past due and accruing	0	1,083
Financial Asset Originated \| Commercial loans \| Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual	0	1,120
Non-accrual with no ACL	0	0
90 days or more past due and accruing	0	0
Financial Asset Originated \| Commercial loans \| Land - acquisition & development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual	0	74
Non-accrual with no ACL	0	0
90 days or more past due and accruing	0	0
Financial Asset Originated \| Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual	20,089	23,242
Non-accrual with no ACL	0	0
90 days or more past due and accruing	0	0
Financial Asset Originated \| Consumer loans \| Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual	847	848
Non-accrual with no ACL	0	0
90 days or more past due and accruing	0	0
Financial Asset Originated \| Consumer loans \| Single-family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual	18,734	21,488
Non-accrual with no ACL	0	0
90 days or more past due and accruing	0	0
Financial Asset Originated \| Consumer loans \| Land - consumer lot loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual	8	0
Non-accrual with no ACL	0	0
90 days or more past due and accruing	0	0
Financial Asset Originated \| Consumer loans \| HELOC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual	300	596
Non-accrual with no ACL	0	0
90 days or more past due and accruing	0	0
Financial Asset Originated \| Consumer loans \| Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual	200	310
Non-accrual with no ACL	0	0
90 days or more past due and accruing	$ 0	$ 0

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.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 310
-SubTopic 20
-Name Accounting Standards Codification
-Section 40
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481628/310-20-40-7

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481990/310-10-45-2

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Amortized cost excluding accrued interest, of financing receivable 90 days or more past due and still accruing. 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 16
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-16

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Amortized cost excluding accrued interest, of financing receivable on nonaccrual status. 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 16
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-16

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+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 16
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-16

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Financing Receivable, Nonaccrual, Percent of Total Loans

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No definition available.

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