Loans Held for Investment and Allowance for Loan Losses - Changes in Allowance for Loan Losses (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 88,734,000	$ 75,834,000
Provision for Loan and Lease Losses	1,256,000	4,707,000
Recoveries	422,000	565,000
Charge-offs	(850,000)	(288,000)
Ending balance	89,562,000	80,818,000
C&I [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	15,698,000	16,129,000
Provision for Loan and Lease Losses	501,000	(64,000)
Recoveries	111,000	52,000
Charge-offs	(204,000)	(34,000)
Ending balance	16,106,000	16,083,000
Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	195,000	1,026,000
Provision for Loan and Lease Losses	(0)	41,000
Recoveries	0	0
Charge-offs	0	0
Ending balance	195,000	1,067,000
Construction & Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	28,553,000	26,443,000
Provision for Loan and Lease Losses	(3,709,000)	2,084,000
Recoveries	0	100,000
Charge-offs	(33,000)	0
Ending balance	24,811,000	28,627,000
Farm [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	2,914,000	1,957,000
Provision for Loan and Lease Losses	(397,000)	(20,000)
Recoveries	0	0
Charge-offs	0	0
Ending balance	2,517,000	1,937,000
Non-Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	13,425,000	9,075,000
Provision for Loan and Lease Losses	1,536,000	(49,000)
Recoveries	7,000	25,000
Charge-offs	0	0
Ending balance	14,968,000	9,051,000
Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	13,813,000	9,928,000
Provision for Loan and Lease Losses	(1,099,000)	2,013,000
Recoveries	42,000	7,000
Charge-offs	0	0
Ending balance	12,756,000	11,948,000
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	11,654,000	9,075,000
Provision for Loan and Lease Losses	1,813,000	624,000
Recoveries	98,000	3,000
Charge-offs	(0)	0
Ending balance	13,565,000	9,702,000
Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	810,000	845,000
Provision for Loan and Lease Losses	384,000	70,000
Recoveries	112,000	132,000
Charge-offs	(399,000)	(190,000)
Ending balance	907,000	857,000
Non-Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	391,000	315,000
Provision for Loan and Lease Losses	210,000	36,000
Recoveries	47,000	45,000
Charge-offs	(154,000)	(64,000)
Ending balance	494,000	332,000
Agriculture [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	1,281,000	1,041,000
Provision for Loan and Lease Losses	2,017,000	(28,000)
Recoveries	5,000	201,000
Charge-offs	(60,000)	0
Ending balance	$ 3,243,000	$ 1,214,000