Allowance for Loan Losses - Schedule of TDR (Detail) $ in Thousands	12 Months Ended
Dec. 31, 2019 USD ($) Contract	Dec. 31, 2018 USD ($) Contract	Dec. 31, 2017 USD ($) Contract
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of Contracts \| Contract	1	2	1
Pre- Modification Outstanding Recorded Investment	$ 382	$ 133	$ 13
Post-Modification Outstanding Recorded Investment	$ 382	$ 133	$ 13
Commercial Real Estate Non Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of Contracts \| Contract	1
Pre- Modification Outstanding Recorded Investment	$ 382
Post-Modification Outstanding Recorded Investment	$ 382
Residential Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of Contracts \| Contract		1	1
Pre- Modification Outstanding Recorded Investment		$ 23	$ 13
Post-Modification Outstanding Recorded Investment		$ 23	$ 13
Farm Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of Contracts \| Contract		1
Pre- Modification Outstanding Recorded Investment		$ 110
Post-Modification Outstanding Recorded Investment		$ 110

Number of financing receivables that have been modified by troubled debt restructurings.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953676-111524

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Amount, after troubled debt restructuring, of modified financing receivable.

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Amount, before troubled debt restructuring, of financing receivable to be modified.

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