Allowance for Credit Losses - Schedule of allowance for credit losses on off-balance sheet credit exposures (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022
Financing Receivable Recorded Investment [Line Items]
Total allowance for credit losses	$ 35,280	$ 35,149	$ 28,511
Off-Balance Sheet Credit Exposures [Member]
Financing Receivable Recorded Investment [Line Items]
Total allowance for credit losses	3,981	3,851
Commercial and Agriculture [Member]
Financing Receivable Recorded Investment [Line Items]
Total allowance for credit losses	5,156	5,540	3,011
Commercial Real Estate Owner Occupied [Member]
Financing Receivable Recorded Investment [Line Items]
Total allowance for credit losses	5,481	5,531	4,565
Commercial Real Estate Non Owner Occupied [Member]
Financing Receivable Recorded Investment [Line Items]
Total allowance for credit losses	11,555	11,646	14,138
Real Estate Construction [Member]
Financing Receivable Recorded Investment [Line Items]
Total allowance for credit losses	3,739	3,447	2,293
Farm Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total allowance for credit losses	227	243	291
Lease Financing Receivables [Member]
Financing Receivable Recorded Investment [Line Items]
Total allowance for credit losses	1,832	1,947	429
Consumer and Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total allowance for credit losses	$ 248	$ 272	$ 98