Loans Held-for-Investment and Allowance for Credit Losses - Schedule of Allowance for Loan Losses by Portfolio Segment (Detail) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2024
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	$ 24,009	$ 22,817	$ 19,077
Loans collectively evaluated for credit losses	77,071	75,508	70,485
Total allowance for loan losses	101,080	98,325	89,562
C&I [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	4,815	4,505	5,711
Loans collectively evaluated for credit losses	10,777	10,931	10,395
Total allowance for loan losses	15,592	15,436	16,106
Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	172
Loans collectively evaluated for credit losses	188	200	195
Total allowance for loan losses	360	200	195
Construction & Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	498	491	2,243
Loans collectively evaluated for credit losses	19,219	19,370	22,568
Total allowance for loan losses	19,717	19,861	24,811
Farm [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	348	450	758
Loans collectively evaluated for credit losses	2,571	2,421	1,759
Total allowance for loan losses	2,919	2,871	2,517
Non-Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	5,628	4,258	3,007
Loans collectively evaluated for credit losses	10,081	10,406	11,961
Total allowance for loan losses	15,709	14,664	14,968
Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	7,322	8,158	2,238
Loans collectively evaluated for credit losses	14,170	13,255	10,518
Total allowance for loan losses	21,492	21,413	12,756
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	4,106	3,660	2,256
Loans collectively evaluated for credit losses	17,633	16,828	11,309
Total allowance for loan losses	21,739	20,488	13,565
Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	7	6	5
Loans collectively evaluated for credit losses	1,488	1,180	902
Total allowance for loan losses	1,495	1,186	907
Non-Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	3	124	129
Loans collectively evaluated for credit losses	490	429	365
Total allowance for loan losses	493	553	494
Agriculture [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	1,110	1,165	2,730
Loans collectively evaluated for credit losses	454	488	513
Total allowance for loan losses	$ 1,564	$ 1,653	$ 3,243