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Investment Securities - Pledged and Transferred Securities (Details) - USD ($) $ in Thousands | Sep. 30, 2021 | Dec. 31, 2020
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Financial Instruments Owned and Pledged as Collateral [Line Items] |  |
Available-for-sale securities pledged as collateral | $ 238,595 | $ 132,431
Public deposits |  |
Financial Instruments Owned and Pledged as Collateral [Line Items] |  |
Available-for-sale securities pledged as collateral | 234,390 | 131,051
Trust deposits |  |
Financial Instruments Owned and Pledged as Collateral [Line Items] |  |
Available-for-sale securities pledged as collateral | 738 | 751
Internal checking account |  |
Financial Instruments Owned and Pledged as Collateral [Line Items] |  |
Available-for-sale securities pledged as collateral | 622 | 629
State of California |  |
Financial Instruments Owned and Pledged as Collateral [Line Items] |  |
Available-for-sale securities pledged as collateral | 235,750 | 132,431
Bankruptcy trustee deposits |  |
Financial Instruments Owned and Pledged as Collateral [Line Items] |  |
Available-for-sale securities pledged as collateral | $ 2,845 | $ 0

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- Definition Sum of the carrying amounts as of the date of the latest financial statement presented of securities which are owned but transferred to another party to serve as collateral to partially or fully secure a debt obligation, repurchase agreement or other current or potential obligation, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 30 -Section 50 -Paragraph 1A -Subparagraph (b)(1)(i) -URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729 + Details
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