Loans - Loan Balances (Detail) - USD ($) $ in Thousands	Jun. 30, 2026	Mar. 31, 2026	Dec. 31, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024
Accounts Notes And Loans Receivable [Line Items]
Total loans	$ 3,254,904		$ 3,270,046
Allowance for credit losses	(41,713)	$ (40,536)	(42,020)	$ (40,455)	$ (40,284)	$ (39,669)
Net loans	3,213,191		3,228,026
Loans Receivable [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans	3,254,904		3,270,046
Allowance for credit losses	(41,713)		(42,020)
Net loans	3,213,191		3,228,026
Commercial and Agriculture [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans	315,479		308,692
Allowance for credit losses	(7,324)	(4,996)	(5,153)	(6,057)	(6,194)	(6,586)
Commercial and Agriculture [Member] \| Loans Receivable [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans	315,479		308,692
Commercial Real Estate Owner Occupied [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans	389,434		385,547
Allowance for credit losses	(4,361)	(4,280)	(4,420)	(4,612)	(4,466)	(4,327)
Commercial Real Estate Owner Occupied [Member] \| Loans Receivable [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans	389,434		385,547
Commercial Real Estate Non Owner Occupied [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans	1,229,731		1,239,017
Allowance for credit losses	(10,665)	(11,789)	(12,118)	(11,321)	(11,412)	(11,404)
Commercial Real Estate Non Owner Occupied [Member] \| Loans Receivable [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans	1,229,731		1,239,017
Residential Real Estate [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans	957,960		944,328
Allowance for credit losses	(14,102)	(14,486)	(14,718)	(13,075)	(12,455)	(11,866)
Residential Real Estate [Member] \| Loans Receivable [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans	957,960		944,328
Real Estate Construction [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans	265,488		285,137
Allowance for credit losses	(3,840)	(3,502)	(3,842)	(3,695)	(4,017)	(3,708)
Real Estate Construction [Member] \| Loans Receivable [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans	265,488		285,137
Farm Real Estate [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans	32,440		37,775
Allowance for credit losses	(226)	(225)	(279)	(305)	(264)	(226)
Farm Real Estate [Member] \| Loans Receivable [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans	32,440		37,775
Lease Financing Receivable [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans	32,665		35,103
Allowance for credit losses	(959)	(1,008)	(1,169)	(1,214)	(1,277)	(1,361)
Lease Financing Receivable [Member] \| Loans Receivable [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans	32,665		35,103
Consumer and Other [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans	31,707		34,447
Allowance for credit losses	(236)	$ (250)	(321)	$ (176)	$ (199)	$ (191)
Consumer and Other [Member] \| Loans Receivable [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans	$ 31,707		$ 34,447