Loans Held-for-Investment and Allowance for Credit Losses - Changes in Allowance for Loan Losses (Detail) - USD ($)	3 Months Ended	9 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 102,792,000	$ 95,170,000	$ 98,325,000	$ 88,734,000
Provision for loan losses	25,506,000	5,552,000	30,929,000	12,718,000
Recoveries	272,000	493,000	1,451,000	1,315,000
Charge-offs	(22,612,000)	(1,279,000)	(24,747,000)	(2,831,000)
Ending balance	105,958,000	99,936,000	105,958,000	99,936,000
C&I [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	17,874,000	15,251,000	15,436,000	15,698,000
Provision for loan losses	18,051,000	(1,665,000)	20,707,000	(1,376,000)
Recoveries	(108,000)	257,000	301,000	545,000
Charge-offs	17,696,000	(398,000)	(18,107,000)	(844,000)
Ending balance	18,337,000	16,775,000	18,337,000	16,775,000
Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	361,000	239,000	200,000	195,000
Provision for loan losses	23,000	(42,000)	138,000	2,000
Recoveries	0	0	0	0
Charge-offs	0	0	0	0
Ending balance	338,000	197,000	338,000	197,000
Agriculture [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	937,000	1,931,000	1,653,000	1,281,000
Provision for loan losses	(2,000)	(294,000)	(792,000)	952,000
Recoveries	(0)	8,000	74,000	59,000
Charge-offs	0	(8,000)	0	(67,000)
Ending balance	935,000	2,225,000	935,000	2,225,000
Construction & Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	22,047,000	23,511,000	19,861,000	28,553,000
Provision for loan losses	881,000	(3,164,000)	3,105,000	(8,173,000)
Recoveries	4,000	0	6,000	0
Charge-offs	(0)	(0)	(40,000)	(33,000)
Ending balance	22,932,000	20,347,000	22,932,000	20,347,000
Farm [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	2,784,000	2,902,000	2,871,000	2,914,000
Provision for loan losses	(94,000)	272,000	(182,000)	(260,000)
Recoveries	(0)	0	1,000	0
Charge-offs	0	0	0	0
Ending balance	2,690,000	3,174,000	2,690,000	3,174,000
Non-Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	14,008,000	13,028,000	14,664,000	13,425,000
Provision for loan losses	(1,175,000)	(869,000)	(761,000)	(454,000)
Recoveries	14,000	3,000	22,000	34,000
Charge-offs	(0)	(0)	(250,000)	(13,000)
Ending balance	15,197,000	13,900,000	15,197,000	13,900,000
Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	21,258,000	21,054,000	21,413,000	13,813,000
Provision for loan losses	(4,371,000)	1,827,000	(4,084,000)	8,988,000
Recoveries	5,000	38,000	312,000	118,000
Charge-offs	4,230,000	0	(4,405,000)	0
Ending balance	21,404,000	22,919,000	21,404,000	22,919,000
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	21,477,000	15,668,000	20,488,000	11,654,000
Provision for loan losses	(713,000)	3,243,000	2,081,000	7,168,000
Recoveries	35,000	0	60,000	100,000
Charge-offs	(163,000)	(174,000)	(567,000)	(185,000)
Ending balance	22,062,000	18,737,000	22,062,000	18,737,000
Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	1,546,000	1,073,000	1,186,000	810,000
Provision for loan losses	333,000	321,000	982,000	1,111,000
Recoveries	103,000	145,000	430,000	346,000
Charge-offs	(384,000)	(428,000)	(1,000,000)	(1,156,000)
Ending balance	1,598,000	1,111,000	1,598,000	1,111,000
Non-Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	500,000	513,000	553,000	391,000
Provision for loan losses	(101,000)	267,000	(45,000)	580,000
Recoveries	3,000	42,000	245,000	113,000
Charge-offs	(139,000)	(271,000)	(378,000)	(533,000)
Ending balance	$ 465,000	$ 551,000	$ 465,000	$ 551,000