Loans Held for Investment and Allowance for Loan Losses - Changes in Allowance for Loan Losses (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 86,541,000	$ 71,932,000	$ 75,834,000	$ 63,465,000
Provision for Loan and Lease Losses	3,821,000	1,060,000	15,050,000	8,910,000
Recoveries	432,000	1,409,000	1,316,000	2,960,000
Charge-offs	(1,080,000)	(293,000)	(2,486,000)	(1,227,000)
Ending balance	89,714,000	74,108,000	89,714,000	74,108,000
C&I [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	16,530,000	18,589,000	16,129,000	12,280,000
Provision for Loan and Lease Losses	(64,000)	(2,378,000)	860,000	3,598,000
Recoveries	56,000	266,000	221,000	824,000
Charge-offs	(715,000)	(38,000)	(1,403,000)	(263,000)
Ending balance	15,807,000	16,439,000	15,807,000	16,439,000
Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	187,000	1,352,000	1,026,000	348,000
Provision for Loan and Lease Losses	(2,000)	(33,000)	(841,000)	971,000
Recoveries	0	0	0	0
Charge-offs	0	0	0	0
Ending balance	185,000	1,319,000	185,000	1,319,000
Construction & Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	28,966,000	21,085,000	26,443,000	17,627,000
Provision for Loan and Lease Losses	(696,000)	4,614,000	1,727,000	8,172,000
Recoveries	6,000	0	106,000	0
Charge-offs	0	0	0	(100,000)
Ending balance	28,276,000	25,699,000	28,276,000	25,699,000
Farm [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	2,804,000	1,006,000	1,957,000	663,000
Provision for Loan and Lease Losses	131,000	149,000	978,000	492,000
Recoveries	0	0	0	0
Charge-offs	0	0	0	0
Ending balance	2,935,000	1,155,000	2,935,000	1,155,000
Non-Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	13,471,000	8,410,000	9,075,000	10,722,000
Provision for Loan and Lease Losses	2,330,000	(498,000)	6,679,000	(3,352,000)
Recoveries	16,000	283,000	63,000	825,000
Charge-offs	0	0	0	0
Ending balance	15,817,000	8,195,000	15,817,000	8,195,000
Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	12,572,000	10,740,000	9,928,000	10,828,000
Provision for Loan and Lease Losses	767,000	(1,303,000)	3,390,000	(1,323,000)
Recoveries	187,000	649,000	208,000	669,000
Charge-offs	0	0	0	(88,000)
Ending balance	13,526,000	10,086,000	13,526,000	10,086,000
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	9,767,000	8,304,000	9,075,000	8,133,000
Provision for Loan and Lease Losses	1,035,000	557,000	1,826,000	860,000
Recoveries	3,000	93,000	18,000	110,000
Charge-offs	(7,000)	0	(121,000)	(149,000)
Ending balance	10,798,000	8,954,000	10,798,000	8,954,000
Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	829,000	912,000	845,000	896,000
Provision for Loan and Lease Losses	172,000	72,000	341,000	116,000
Recoveries	96,000	47,000	329,000	215,000
Charge-offs	(235,000)	(119,000)	(653,000)	(315,000)
Ending balance	862,000	912,000	862,000	912,000
Non-Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	333,000	372,000	315,000	371,000
Provision for Loan and Lease Losses	95,000	67,000	218,000	106,000
Recoveries	47,000	53,000	128,000	182,000
Charge-offs	(123,000)	(136,000)	(309,000)	(303,000)
Ending balance	352,000	356,000	352,000	356,000
Agriculture [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	1,082,000	1,162,000	1,041,000	1,597,000
Provision for Loan and Lease Losses	53,000	(187,000)	(128,000)	(730,000)
Recoveries	21,000	18,000	243,000	135,000
Charge-offs	0	0	0	(9,000)
Ending balance	$ 1,156,000	$ 993,000	$ 1,156,000	$ 993,000