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Securities - Additional Information (Details) |  | 12 Months Ended |
--- | --- | --- | ---
Jan. 01, 2019 USD ($) | Dec. 31, 2019 USD ($) Security | Dec. 31, 2018 USD ($) Security
Schedule Of Investments [Line Items] |  |  |
Trading securities |  | $ 0 | $ 0
Reclassification from other comprehensive income to retained earnings |  | (1,440,000) |
Equity and other securities, at fair value |  | 8,031,000 |
Carrying amount of securities pledged as collateral |  | $ 301,100,000 | $ 244,700,000
Minimum |  |  |
Schedule Of Investments [Line Items] |  |  |
Percentage of shareholders equity for which securities holdings exceeds for no issuer other than U.S. Government and agencies |  | 10.00% | 10.00%
Federal Home Loan Bank Advances |  |  |
Schedule Of Investments [Line Items] |  |  |
Carrying amount of securities pledged as collateral |  | $ 0 | $ 0
Public Fund Deposits |  |  |
Schedule Of Investments [Line Items] |  |  |
Carrying amount of securities pledged as collateral |  | 240,400,000 | 197,800,000
Customer Repurchase Agreements |  |  |
Schedule Of Investments [Line Items] |  |  |
Carrying amount of securities pledged as collateral |  | $ 55,700,000 | $ 46,900,000
Available-for-sale Securities |  |  |
Schedule Of Investments [Line Items] |  |  |
Investment securities with unrealized losses | Security |  | 99 | 179
Held-to-maturity Securities |  |  |
Schedule Of Investments [Line Items] |  |  |
Investment securities with unrealized losses | Security |  | 0 | 46
ASU 2016-01 |  |  |
Schedule Of Investments [Line Items] |  |  |
Reclassification from other comprehensive income to retained earnings | $ 1,400,000 |  |
Equity and other securities, at fair value |  |  | $ 6,600,000
ASU 2017-12 |  |  |
Schedule Of Investments [Line Items] |  |  |
Reclassification of securities held-to-maturity to securities available-for-sale | $ 94,800,000 |  |

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- Definition Percentage of shareholders equity for which securities holdings exceeds for no issuer other than U.S. Government and agencies. + References No definition available. + Details
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