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Loans Receivable - Narrative (Details) | 3 Months Ended |
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Dec. 31, 2024 USD ($) portfolioSegment | Sep. 30, 2024 USD ($)
Receivables [Abstract] |  |
Number of portfolio segments for loans held for investment | portfolioSegment | 2 |
Accrued interest receivables for loans | $ 91,214,000 | $ 92,362,000
Loans pledged to secure borrowings from the Federal Home Loan Bank | 13,985,988,000 |
Nonaccrual interest income recognized | 761,000 |
Individually evaluated for credit loss, interest income | 924,000 |
Loan modified, subsequent default | $ 0 |

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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/1943274/2147478878/942-470-45-1 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/1943274/2147477734/942-470-50-3 + Details
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Period Type: | instant

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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 Amortized cost excluding accrued interest, of financing receivable with payment default in current period and modified within previous 12 months preceding payment default for debtor experiencing financial difficulty. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 44 -Subparagraph (a)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481962/310-10-50-44 + Details
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- Definition Amount of interest income on financing receivable on nonaccrual status. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 16 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-16 + Details
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- References No definition available. + Details
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- Definition Financing Receivable, Individually Evaluated for Credit Loss, Interest Income + References No definition available. + Details
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- Definition Number Of Portfolio Segments For Loans Held For Investment + References No definition available. + Details
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