Loans Held for Investment and Allowance for Loan Losses - Changes in Allowance for Loan Losses (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 75,834,000	$ 63,465,000
Provision for Loan and Lease Losses	4,707,000	3,747,000
Recoveries	565,000	360,000
Charge-offs	(288,000)	(659,000)
Ending balance	80,818,000	66,913,000
C&I [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	16,129,000	12,280,000
Provision for Loan and Lease Losses	(64,000)	3,455,000
Recoveries	52,000	156,000
Charge-offs	(34,000)	(154,000)
Ending balance	16,083,000	15,737,000
Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	1,026,000	348,000
Provision for Loan and Lease Losses	41,000	1,070,000
Recoveries	0	0
Charge-offs	0	0
Ending balance	1,067,000	1,418,000
Construction & Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	26,443,000	17,627,000
Provision for Loan and Lease Losses	2,084,000	360,000
Recoveries	100,000	0
Charge-offs	0	(100,000)
Ending balance	28,627,000	17,887,000
Farm [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	1,957,000	663,000
Provision for Loan and Lease Losses	20,000	210,000
Recoveries	0	0
Charge-offs	0	0
Ending balance	1,937,000	873,000
Non-Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	9,075,000	10,722,000
Provision for Loan and Lease Losses	(49,000)	(2,278,000)
Recoveries	25,000	55,000
Charge-offs	0	0
Ending balance	9,051,000	8,499,000
Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	9,928,000	10,828,000
Provision for Loan and Lease Losses	2,013,000	789,000
Recoveries	7,000	7,000
Charge-offs	0	(88,000)
Ending balance	11,948,000	11,536,000
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	9,075,000	8,133,000
Provision for Loan and Lease Losses	624,000	(163,000)
Recoveries	3,000	5,000
Charge-offs	0	(146,000)
Ending balance	9,702,000	7,829,000
Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	845,000	896,000
Provision for Loan and Lease Losses	70,000	(20,000)
Recoveries	132,000	66,000
Charge-offs	(190,000)	(73,000)
Ending balance	857,000	869,000
Non-Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	315,000	371,000
Provision for Loan and Lease Losses	36,000	35,000
Recoveries	45,000	46,000
Charge-offs	(64,000)	(98,000)
Ending balance	332,000	354,000
Agriculture [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	1,041,000	1,597,000
Provision for Loan and Lease Losses	28,000	289,000
Recoveries	201,000	25,000
Charge-offs	0	0
Ending balance	$ 1,214,000	$ 1,911,000