Loans Held-for-Investment and Allowance for Credit Losses - Schedule of Allowance for Loan Losses by Portfolio Segment (Detail) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024	Sep. 30, 2024
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	$ 26,381	$ 22,817	$ 24,892
Loans collectively evaluated for credit losses	79,577	75,508	75,044
Total allowance for loan losses	105,958	98,325	99,936
C&I [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	8,334	4,505	5,351
Loans collectively evaluated for credit losses	10,003	10,931	11,424
Total allowance for loan losses	18,337	15,436	16,775
Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	152	0	0
Loans collectively evaluated for credit losses	186	200	197
Total allowance for loan losses	338	200	197
Construction & Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	1,777	491	591
Loans collectively evaluated for credit losses	21,155	19,370	19,756
Total allowance for loan losses	22,932	19,861	20,347
Farm [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	237	450	989
Loans collectively evaluated for credit losses	2,453	2,421	2,185
Total allowance for loan losses	2,690	2,871	3,174
Non-Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	4,285	4,258	3,449
Loans collectively evaluated for credit losses	10,912	10,406	10,451
Total allowance for loan losses	15,197	14,664	13,900
Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	7,081	8,158	9,597
Loans collectively evaluated for credit losses	14,323	13,255	13,322
Total allowance for loan losses	21,404	21,413	22,919
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	3,993	3,660	3,017
Loans collectively evaluated for credit losses	18,069	16,828	15,720
Total allowance for loan losses	22,062	20,488	18,737
Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	8	6	5
Loans collectively evaluated for credit losses	1,590	1,180	1,106
Total allowance for loan losses	1,598	1,186	1,111
Non-Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	3	124	165
Loans collectively evaluated for credit losses	462	429	386
Total allowance for loan losses	465	553	551
Agriculture [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	511	1,165	1,728
Loans collectively evaluated for credit losses	424	488	497
Total allowance for loan losses	$ 935	$ 1,653	$ 2,225

Financing Receivable, Allowance for Credit Losses [Line Items]