Loans and Allowance for Credit Losses - Schedule of Allowance for Loan Losses by Portfolio Segment Allowance (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for Loan Losses, Beginning Balance	$ 44,449	$ 45,103	$ 43,520	$ 45,847
Provision for credit losses	265	298	1,265	(68)
Initial PCD on Acquired loans			596
Loans charged-off	(1,380)	(1,068)	(2,262)	(1,706)
Recoveries	153	211	368	471
Allowance for Loan Losses, Ending Balance	43,487	44,544	43,487	44,544
Commercial Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for Loan Losses, Beginning Balance	13,582	16,611	13,476	16,731
Provision for credit losses	888	(20)	1,004	(146)
Loans charged-off	(2)	(9)	(19)	(10)
Recoveries	24	70	31	77
Allowance for Loan Losses, Ending Balance	14,492	16,652	14,492	16,652
Commercial and Industrial [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for Loan Losses, Beginning Balance	17,651	15,620	17,954	14,951
Provision for credit losses	(87)	167	(20)	1,267
Initial PCD on Acquired loans			119
Loans charged-off	(1,211)	(640)	(1,842)	(1,075)
Recoveries	54	47	196	51
Allowance for Loan Losses, Ending Balance	16,407	15,194	16,407	15,194
Residential Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for Loan Losses, Beginning Balance	8,319	8,751	7,784	8,608
Provision for credit losses	(256)	114	112	246
Initial PCD on Acquired loans			184
Loans charged-off	(6)	(52)	(33)	(57)
Recoveries	9	42	19	58
Allowance for Loan Losses, Ending Balance	8,066	8,855	8,066	8,855
Agricultural Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for Loan Losses, Beginning Balance	1,688	586	1,718	819
Provision for credit losses	566	(6)	535	(239)
Loans charged-off	(1)		(1)
Recoveries	1	3	2	3
Allowance for Loan Losses, Ending Balance	2,254	583	2,254	583
Agricultural [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for Loan Losses, Beginning Balance	1,612	1,547	995	2,457
Provision for credit losses	(1,090)	(150)	(731)	(1,215)
Initial PCD on Acquired loans			284
Loans charged-off	(1)	(108)	(27)	(108)
Recoveries	1	0	1	155
Allowance for Loan Losses, Ending Balance	522	1,289	522	1,289
Consumer [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for Loan Losses, Beginning Balance	1,597	1,988	1,593	2,281
Provision for credit losses	244	193	365	19
Initial PCD on Acquired loans			9
Loans charged-off	(159)	(259)	(340)	(456)
Recoveries	64	49	119	127
Allowance for Loan Losses, Ending Balance	$ 1,746	$ 1,971	$ 1,746	$ 1,971