Allowance for Loan Losses - Aging Analysis of Past Due Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 2,250	$ 3,624
Total Loans	2,004,814	2,057,502
Past Due 90 Days and Accruing	430
30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	634	1,235
60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	262	897
90 Days or Greater [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,354	1,492
Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,002,268	2,053,490
Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Purchased Credit-Impaired Loans	296	388
Commercial and Agriculture [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	400	192
Total Loans	276,741	409,876
Commercial and Agriculture [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	400	117
Commercial and Agriculture [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		25
Commercial and Agriculture [Member] | 90 Days or Greater [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		50
Commercial and Agriculture [Member] | Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	276,341	409,684
Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	585	106
Total Loans	292,725	278,413
Past Due 90 Days and Accruing	430
Commercial Real Estate Owner Occupied [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	10	4
Commercial Real Estate Owner Occupied [Member] | 90 Days or Greater [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	575	102
Commercial Real Estate Owner Occupied [Member] | Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	292,140	278,307
Commercial Real Estate Non Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4	6
Total Loans	788,898	705,072
Commercial Real Estate Non Owner Occupied [Member] | 90 Days or Greater [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4	6
Commercial Real Estate Non Owner Occupied [Member] | Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	788,894	705,066
Residential Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,161	3,240
Total Loans	424,553	442,588
Residential Real Estate [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	147	1,059
Residential Real Estate [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	248	867
Residential Real Estate [Member] | 90 Days or Greater [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	766	1,314
Residential Real Estate [Member] | Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	423,096	438,960
Residential Real Estate [Member] | Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Purchased Credit-Impaired Loans	296	388
Real Estate Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	179,491	175,609
Real Estate Construction [Member] | Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	179,491	175,609
Farm Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		4
Total Loans	30,147	33,102
Farm Real Estate [Member] | 90 Days or Greater [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		4
Farm Real Estate [Member] | Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	30,147	33,098
Consumer and Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	100	76
Total Loans	12,259	12,842
Consumer and Other [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	87	59
Consumer and Other [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4	1
Consumer and Other [Member] | 90 Days or Greater [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	9	16
Consumer and Other [Member] | Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 12,159	$ 12,766