Loans - Impaired Loans Classified as Troubled Debt Restructured (Detail) $ in Thousands	12 Months Ended
Dec. 31, 2020 USD ($) Contract	Dec. 31, 2019 USD ($) Contract
Consumer Real Estate [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts Modified in the Last 12 Months \| Contract		1
Pre-Modification Outstanding Recorded Investment		$ 74
Post-Modification Outstanding Recorded Investment		$ 74
Agricultural Real Estate [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts Modified in the Last 12 Months \| Contract	2
Pre-Modification Outstanding Recorded Investment	$ 5,380
Post-Modification Outstanding Recorded Investment	$ 5,380
Commercial and Industrial [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts Modified in the Last 12 Months \| Contract	1	4
Pre-Modification Outstanding Recorded Investment	$ 50	$ 812
Post-Modification Outstanding Recorded Investment	$ 50	$ 812
Agricultural [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts Modified in the Last 12 Months \| Contract	1
Pre-Modification Outstanding Recorded Investment	$ 164
Post-Modification Outstanding Recorded Investment	$ 164
Commercial Real Estate [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts Modified in the Last 12 Months \| Contract	2
Pre-Modification Outstanding Recorded Investment	$ 981
Post-Modification Outstanding Recorded Investment	$ 981

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

+ References

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=121611835&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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