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, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 95,170,000	$ 86,541,000	$ 88,734,000	$ 75,834,000
Provision for loan losses	5,552,000	3,821,000	12,718,000	15,050,000
Recoveries	493,000	432,000	1,315,000	1,316,000
Charge-offs	(1,279,000)	(1,080,000)	(2,831,000)	(2,486,000)
Ending balance	99,936,000	89,714,000	99,936,000	89,714,000
C&I [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	15,251,000	16,530,000	15,698,000	16,129,000
Provision for loan losses	1,665,000	(64,000)	1,376,000	860,000
Recoveries	257,000	56,000	545,000	221,000
Charge-offs	(398,000)	(715,000)	(844,000)	(1,403,000)
Ending balance	16,775,000	15,807,000	16,775,000	15,807,000
Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	239,000	187,000	195,000	1,026,000
Provision for loan losses	(42,000)	(2,000)	2,000	(841,000)
Recoveries	0	0	0	0
Charge-offs	0	0	0	0
Ending balance	197,000	185,000	197,000	185,000
Agriculture [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	1,931,000	1,082,000	1,281,000	1,041,000
Provision for loan losses	294,000	53,000	952,000	(128,000)
Recoveries	8,000	21,000	59,000	243,000
Charge-offs	(8,000)	0	(67,000)	0
Ending balance	2,225,000	1,156,000	2,225,000	1,156,000
Construction & Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	23,511,000	28,966,000	28,553,000	26,443,000
Provision for loan losses	(3,164,000)	(696,000)	(8,173,000)	1,727,000
Recoveries	0	6,000	0	106,000
Charge-offs	0	0	(33,000)	0
Ending balance	20,347,000	28,276,000	20,347,000	28,276,000
Farm [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	2,902,000	2,804,000	2,914,000	1,957,000
Provision for loan losses	272,000	131,000	260,000	978,000
Recoveries	0	0	0	0
Charge-offs	0	0	0	0
Ending balance	3,174,000	2,935,000	3,174,000	2,935,000
Non-Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	13,028,000	13,471,000	13,425,000	9,075,000
Provision for loan losses	869,000	2,330,000	454,000	6,679,000
Recoveries	3,000	16,000	34,000	63,000
Charge-offs	0	0	(13,000)	0
Ending balance	13,900,000	15,817,000	13,900,000	15,817,000
Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	21,054,000	12,572,000	13,813,000	9,928,000
Provision for loan losses	1,827,000	767,000	8,988,000	3,390,000
Recoveries	38,000	187,000	118,000	208,000
Charge-offs	0	0	0	0
Ending balance	22,919,000	13,526,000	22,919,000	13,526,000
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	15,668,000	9,767,000	11,654,000	9,075,000
Provision for loan losses	3,243,000	1,035,000	7,168,000	1,826,000
Recoveries	0	3,000	100,000	18,000
Charge-offs	(174,000)	(7,000)	(185,000)	(121,000)
Ending balance	18,737,000	10,798,000	18,737,000	10,798,000
Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	1,073,000	829,000	810,000	845,000
Provision for loan losses	321,000	172,000	1,111,000	341,000
Recoveries	145,000	96,000	346,000	329,000
Charge-offs	(428,000)	(235,000)	(1,156,000)	(653,000)
Ending balance	1,111,000	862,000	1,111,000	862,000
Non-Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	513,000	333,000	391,000	315,000
Provision for loan losses	267,000	95,000	580,000	218,000
Recoveries	42,000	47,000	113,000	128,000
Charge-offs	(271,000)	(123,000)	(533,000)	(309,000)
Ending balance	$ 551,000	$ 352,000	$ 551,000	$ 352,000