Loans Held-for-Investment and Allowance for Credit Losses - Schedule of Loans Held-for-Investment by portfolio segment (Detail) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025
Loans and Leases Receivable Disclosure [Line Items]
Total Loans	$ 8,346,931	$ 8,158,276
Less-allowance for credit losses	(112,433)	(105,536)
Loans, net	8,234,498	8,052,740
Commercial [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total Loans	1,506,726	1,458,962
Commercial [Member] \| Commercial & Industrial [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total Loans	1,087,656	1,116,461
Commercial [Member] \| Municipal [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total Loans	419,070	342,501
Agriculture [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total Loans	81,786	95,776
Real Estate [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total Loans	5,833,587	5,724,744
Real Estate [Member] \| Construction & Development [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total Loans	1,191,082	1,157,865
Real Estate [Member] \| Farm [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total Loans	344,483	327,625
Real Estate [Member] \| Non-Owner Occupied CRE [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total Loans	831,929	832,816
Real Estate [Member] \| Owner Occupied CRE [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total Loans	1,144,093	1,120,608
Real Estate [Member] \| Residential [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total Loans	2,322,000	2,285,830
Consumer [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total Loans	924,832	878,794
Consumer [Member] \| Auto [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total Loans	776,433	732,351
Consumer [Member] \| Non-Auto [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total Loans	$ 148,399	$ 146,443