Loans Held-for-Investment and Allowance for Credit Losses - Changes in Allowance for Loan Losses (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 98,325,000	$ 88,734,000
Provision for loan losses	2,991,000	1,256,000
Recoveries	710,000	422,000
Charge-offs	(946,000)	(850,000)
Ending balance	101,080,000	89,562,000
C&I [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	15,436,000	15,698,000
Provision for loan losses	154,000	501,000
Recoveries	93,000	111,000
Charge-offs	(91,000)	(204,000)
Ending balance	15,592,000	16,106,000
Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	200,000	195,000
Provision for loan losses	160,000	0
Recoveries	0	0
Charge-offs	0	0
Ending balance	360,000	195,000
Agriculture [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	1,653,000	1,281,000
Provision for loan losses	(125,000)	2,017,000
Recoveries	36,000	5,000
Charge-offs	0	(60,000)
Ending balance	1,564,000	3,243,000
Construction & Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	19,861,000	28,553,000
Provision for loan losses	(144,000)	(3,709,000)
Recoveries	0	0
Charge-offs	0	(33,000)
Ending balance	19,717,000	24,811,000
Farm [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	2,871,000	2,914,000
Provision for loan losses	47,000	(397,000)
Recoveries	1,000	0
Charge-offs	0	0
Ending balance	2,919,000	2,517,000
Non-Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	14,664,000	13,425,000
Provision for loan losses	1,042,000	1,536,000
Recoveries	3,000	7,000
Charge-offs	0	0
Ending balance	15,709,000	14,968,000
Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	21,413,000	13,813,000
Provision for loan losses	(48,000)	(1,099,000)
Recoveries	302,000	42,000
Charge-offs	(175,000)	0
Ending balance	21,492,000	12,756,000
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	20,488,000	11,654,000
Provision for loan losses	1,498,000	1,813,000
Recoveries	3,000	98,000
Charge-offs	(250,000)	0
Ending balance	21,739,000	13,565,000
Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	1,186,000	810,000
Provision for loan losses	450,000	384,000
Recoveries	198,000	112,000
Charge-offs	(339,000)	(399,000)
Ending balance	1,495,000	907,000
Non-Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	553,000	391,000
Provision for loan losses	(43,000)	210,000
Recoveries	74,000	47,000
Charge-offs	(91,000)	(154,000)
Ending balance	$ 493,000	$ 494,000