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Investment Securities - Securities Sold, Pledged as Collateral and Transfers (Details) - USD ($) $ in Thousands |  | 3 Months Ended | 9 Months Ended |
--- | --- | --- | --- | ---
Feb. 24, 2017 | Sep. 30, 2017 | Sep. 30, 2016 | Sep. 30, 2017 | Sep. 30, 2016 | Dec. 31, 2016
Available-for-sale: |  |  |  |  |  |
Sales proceeds |  | $ 0 | $ 0 | $ 1,321 | $ 68,673 |
Gross realized gains |  | 0 | 0 | 13 | 458 |
Gross realized losses |  | 0 | $ 0 | (3) | (64) |
Financial Instruments Owned and Pledged as Collateral [Line Items] |  |  |  |  |  |
Securities transferred from available-for-sale to held-to-maturity | $ 129,000 |  |  | 128,965 | $ 0 |
Unrealized pre-tax loss from transfer of available-for-sale securities to held-to-maturity | $ 3,000 |  |  |  |  |
State of California |  |  |  |  |  |
Financial Instruments Owned and Pledged as Collateral [Line Items] |  |  |  |  |  |
Available-for-sale securities pledged as collateral |  | 112,400 |  | 112,400 |  | $ 109,100
Public Deposits |  |  |  |  |  |
Financial Instruments Owned and Pledged as Collateral [Line Items] |  |  |  |  |  |
Available-for-sale securities pledged as collateral |  | 111,600 |  | 111,600 |  | 108,300
Trust Deposits |  |  |  |  |  |
Financial Instruments Owned and Pledged as Collateral [Line Items] |  |  |  |  |  |
Available-for-sale securities pledged as collateral |  | 777 |  | 777 |  | 822
Internal checking account |  |  |  |  |  |
Financial Instruments Owned and Pledged as Collateral [Line Items] |  |  |  |  |  |
Available-for-sale securities pledged as collateral |  | $ 2,000 |  | $ 2,000 |  | $ 2,100

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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 This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27357-111563 + Details
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- Definition This item represents the gross loss realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27357-111563 + 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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- Definition The cash inflow associated with the sale of debt and equity securities classified as available-for-sale securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26853-111562 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (a),(b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3179-108585 + Details
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