| Securities - Additional Information (Detail) | 3 Months Ended | |
|---|---|---|
| Mar. 31, 2020  USD ($)  Security | Mar. 31, 2019  USD ($) | |
| Investments Debt And Equity Securities [Abstract] | ||
| Number of securities sales transactions | Security | 0 | |
| Net gain (loss) in earnings resulting from sale of securities | $ 725,000 | |
| Net unrealized gain (losses) recorded in comprehensive income | (206,000) | |
| Available for sale securities pledged as collateral | $ 52,700,000 | $ 30,000,000.0 | 
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- Definition Number of securities sales transactions. No definition available. 
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- Definition Amount of realized gain (loss) from sale of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef 
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- References No definition available. 
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- Definition Amount after tax, before reclassification adjustments, of unrealized holding gain (loss) on available-for-sale securities and unrealized holding gain (loss) related to transfers of securities into the available-for-sale classification and out of the held-to-maturity classification. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Definition The carrying amount as of the date of the latest financial statement presented of mortgage-related securities classified as available for sale or held for investment 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 does not have the right by contract or custom to sell or re-pledge them to an unrelated party. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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