Allowance for Loan Losses - Impaired Loans - Average Recorded Investment and Interest Income Recognized (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	$ 3,085	$ 3,520	$ 5,243
Interest Income Recognized	172	167	216
Commercial and Agriculture [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	367	636	1,375
Interest Income Recognized	33	25	34
Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	456	610	1,507
Interest Income Recognized	32	33	75
Commercial Real Estate Non Owner Occupied [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	308	39	233
Interest Income Recognized	20	5	6
Residential Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	1,271	1,519	1,515
Interest Income Recognized	58	75	73
Farm Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	683	716	613
Interest Income Recognized	$ 29	$ 29	$ 28

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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- Definition

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5212-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5258-111524

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- Definition

Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

+ References

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