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Regulatory Matters - Additional Information (Detail) - USD ($) $ in Thousands | 12 Months Ended |  |  |  |
--- | --- | --- | --- | --- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Jan. 01, 2019 | Jan. 01, 2018 | Jan. 01, 2017 | Jan. 01, 2016
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] |  |  |  |  |  |
Capital conservation buffer period | 4 years |  |  |  |  |
Cash dividends on common stock | $ 692 | $ 591 |  |  |  |
Capital conservation buffer percentage | 1.25% | 0.625% |  |  | 0.625% | 0.625%
Capital conservation buffer percentage maintained at bank | 5.12% | 5.47% |  |  |  |
Scenario, Forecast |  |  |  |  |  |
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] |  |  |  |  |  |
Capital conservation buffer percentage |  |  | 0.625% | 0.625% |  |
First Bank |  |  |  |  |  |
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] |  |  |  |  |  |
Cash dividends on common stock | $ 5,500 |  |  |  |  |

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- Definition Amount of paid and unpaid common stock dividends declared with the form of settlement in cash. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 + Details
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