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Summary of Significant Accounting Policies - Narrative (Details) |  | 6 Months Ended |  |
--- | --- | --- | --- | ---
Mar. 01, 2024 USD ($) | Mar. 31, 2025 USD ($) portfolioSegment branch classOfPortfolioSegment | Dec. 31, 2024 USD ($) | Sep. 30, 2024 USD ($)
Summary of Significant Accounting Policies [Line Items] |  |  |  |
Number of offices | branch |  | 209 |  |
Cash collateral |  | $ 171,300,000 |  | $ 168,200,000
Fair value of NAV |  | 34,919,798 |  |
Remaining unfunded commitment |  | $ 15,119,262 |  |
Number of portfolio segments for loans held for investment | portfolioSegment |  | 2 |  |
Number of classes disaggregating the commercial loan portfolio | classOfPortfolioSegment |  | 5 |  |
Number of classes disaggregating the consumer loan portfolio | classOfPortfolioSegment |  | 5 |  |
Goodwill |  | $ 414,723,000 | $ 414,723,000 | $ 411,360,000
Luther Burbank |  |  |  |
Summary of Significant Accounting Policies [Line Items] |  |  |  |
Goodwill | $ 107,890,000 |  |  |
Other intangible assets | $ 37,022,000 |  |  |
Acquired intangible assets, useful life | 6 years |  |  |

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