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Investment Securities - Schedule of Financial Instruments Owned and Pledged as Collateral (Details) - USD ($) $ in Thousands | Sep. 30, 2025 | Dec. 31, 2024
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Financial Instruments Owned and Pledged as Collateral [Line Items] |  |
Total pledged investment securities | $ 913,169 | $ 941,122
Total investment securities pledged to the State of California |  |
Financial Instruments Owned and Pledged as Collateral [Line Items] |  |
Total pledged investment securities | 322,154 | 290,564
Secure public deposits in compliance with the Local Agency Security Program |  |
Financial Instruments Owned and Pledged as Collateral [Line Items] |  |
Total pledged investment securities | 319,454 | 288,385
Collateral for trust deposits |  |
Financial Instruments Owned and Pledged as Collateral [Line Items] |  |
Total pledged investment securities | 1,200 | 1,284
Collateral for Wealth Management and Trust Services checking account |  |
Financial Instruments Owned and Pledged as Collateral [Line Items] |  |
Total pledged investment securities | 1,500 | 895
Bankruptcy trustee deposits pledged with Federal Reserve Bank |  |
Financial Instruments Owned and Pledged as Collateral [Line Items] |  |
Total pledged investment securities | 2,138 | 651
Pledged to FHLB Securities-Backed Credit Program |  |
Financial Instruments Owned and Pledged as Collateral [Line Items] |  |
Total pledged investment securities | 269,768 | 284,148
Pledged to the Federal Reserve Discount Window |  |
Financial Instruments Owned and Pledged as Collateral [Line Items] |  |
Total pledged investment securities | $ 319,109 | $ 365,759

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