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Investment Securities - Pledged and Transferred Securities (Details) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2018 | Mar. 31, 2017 | Dec. 31, 2017
Financial Instruments Owned and Pledged as Collateral [Line Items] |  |  |
Securities transferred from available-for-sale to held-to-maturity | $ 0 | $ 128,965 | $ 129,000
Unrealized pre-tax loss from transfer of available-for-sale securities to held-to-maturity |  |  | 3,000
Amortization of net unrealized loss on available-for-sale securities transferred to held-to-maturity | 136 | $ 41 | 41
Public Deposits |  |  |
Financial Instruments Owned and Pledged as Collateral [Line Items] |  |  |
Available-for-sale securities pledged as collateral | 102,738 |  | 107,829
Trust Deposits |  |  |
Financial Instruments Owned and Pledged as Collateral [Line Items] |  |  |
Available-for-sale securities pledged as collateral | 754 |  | 761
State of California |  |  |
Financial Instruments Owned and Pledged as Collateral [Line Items] |  |  |
Available-for-sale securities pledged as collateral | 103,492 |  | 108,590
Internal checking account |  |  |
Financial Instruments Owned and Pledged as Collateral [Line Items] |  |  |
Available-for-sale securities pledged as collateral | $ 2,018 |  | $ 2,026

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- Definition Amortization Of Net Unrealized Loss On Available-For-Sale Securities Transferred To Held-To-Maturity + References No definition available. + Details
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- Definition Available-for-sale Securities, Transferred to Held-to-maturity Securities + References No definition available. + Details
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- Definition Available-for-sale Securities, Transferred to Held-to-maturity Securities, Unrealized Gain (Loss) + References No definition available. + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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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://www.xbrl.org/2003/role/presentationRef -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=64858031&loc=SL6224234-111729 + Details
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