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Loans Receivable - Narrative (Details) $ in Thousands | 3 Months Ended |
--- | --- | ---
Dec. 31, 2023 USD ($) portfolioSegment loan | Sep. 30, 2023 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Number of portfolio segments for loans held for investment | portfolioSegment | 2 |
Accrued interest receivables for loans | $ 77,760 | $ 77,349
Loans pledged to secure borrowings from the Federal Home Loan Bank | 10,493,301 | $ 8,941,201
Nonaccrual interest income recognized | 511 |
Impaired, interest income on accrual accrual and performed loans | $ 625 |
Commercial loans | Commercial & industrial |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Number of loans modified, past due | loan | 1 |
Commercial loans | Commercial & industrial | Total Delinquent |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Loan modified, accumulated amortized cost | $ 1,659 |

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- Definition Amount of the collateral pledged in support of federal home loan bank advances outstanding. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 470 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480876/942-470-45-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 50 -Paragraph 3 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480848/942-470-50-3 + Details
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- Definition Amount, before allowance for credit loss, of accrued interest on financing receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3B -Publisher FASB -URI https://asc.fasb.org//1943274/2147479319/326-20-50-3B + Details
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- Definition Accumulated amortized cost excluding accrued interest, of financing receivable modified for debtor experiencing financial difficulty. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 42 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481962/310-10-50-42 + Details
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