Loans and ACL - Summary of Aging of amortized cost of loans held for investment by loan category (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Financing Receivable, Past Due [Line Items]
Days past due	$ 2,258,443	$ 2,430,117
Nonaccrual	23,671	60,026
Gross loans	2,258,443	2,430,117
Deferred loan fees, net of costs	836	830
Total	2,259,279	2,430,947
Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual	23,671	60,026
Nonaccrual loans with no allowance | Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual	557	4,088
Non accrual loans with an allowance | Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual	23,114	55,938
30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total	13,493	14,282
60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total	6,643	1,913
Greater than 90 Days Past Due & Accruing [Member]
Financing Receivable, Past Due [Line Items]
Total	3,127	3,037
Current Loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable Recorded Investments Current	2,212,345	2,351,689
Deferred loan fees, net of costs	836	830
Commercial and Industrial [Member]
Financing Receivable, Past Due [Line Items]
Days past due	401,589	508,944
Nonaccrual	10,285	39,429
Gross loans	401,589	508,944
Commercial and Industrial [Member] | Nonaccrual loans with no allowance
Financing Receivable, Past Due [Line Items]
Nonaccrual		1,487
Commercial and Industrial [Member] | Non accrual loans with an allowance
Financing Receivable, Past Due [Line Items]
Nonaccrual	10,285	37,942
Commercial and Industrial [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Days past due	2,150	2,235
Gross loans	2,150	2,235
Commercial and Industrial [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Days past due	1,526	632
Gross loans	1,526	632
Commercial and Industrial [Member] | Greater than 90 Days Past Due & Accruing [Member]
Financing Receivable, Past Due [Line Items]
Days past due	2,751	1,709
Gross loans	2,751	1,709
Commercial and Industrial [Member] | Current Loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable Recorded Investments Current	384,877	464,939
Construction, commercial [Member] | Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Days past due	135,517	180,052
Nonaccrual	320	383
Gross loans	135,517	180,052
Construction, commercial [Member] | Non accrual loans with an allowance | Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual	320	383
Construction, commercial [Member] | 30-59 Days Past Due [Member] | Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Days past due		2,016
Gross loans		2,016
Construction, commercial [Member] | 60-89 Days Past Due [Member] | Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Days past due	1,180
Gross loans	1,180
Construction, commercial [Member] | Current Loans [Member] | Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable Recorded Investments Current	134,017	177,653
Construction, Residential [Member] | Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Days past due	55,849	75,832
Gross loans	55,849	75,832
Construction, Residential [Member] | 30-59 Days Past Due [Member] | Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Days past due		523
Gross loans		523
Construction, Residential [Member] | Current Loans [Member] | Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable Recorded Investments Current	55,849	75,309
Commercial [Member] | Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Days past due	879,098	870,540
Nonaccrual	6,374	11,880
Gross loans	879,098	870,540
Commercial [Member] | Nonaccrual loans with no allowance | Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual	0	2,024
Commercial [Member] | Non accrual loans with an allowance | Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual	6,374	9,856
Commercial [Member] | 30-59 Days Past Due [Member] | Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Days past due	8,647	2,109
Gross loans	8,647	2,109
Commercial [Member] | 60-89 Days Past Due [Member] | Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Days past due	359	714
Gross loans	359	714
Commercial [Member] | Greater than 90 Days Past Due & Accruing [Member] | Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Days past due		574
Gross loans		574
Commercial [Member] | Current Loans [Member] | Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable Recorded Investments Current	863,718	855,263
Residential [Member] | Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Days past due	727,246	730,110
Nonaccrual	6,023	7,580
Gross loans	727,246	730,110
Residential [Member] | Nonaccrual loans with no allowance | Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual	557	577
Residential [Member] | Non accrual loans with an allowance | Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual	5,466	7,003
Residential [Member] | 30-59 Days Past Due [Member] | Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Days past due	501	5,101
Gross loans	501	5,101
Residential [Member] | 60-89 Days Past Due [Member] | Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Days past due	2,906	288
Gross loans	2,906	288
Residential [Member] | Current Loans [Member] | Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable Recorded Investments Current	717,816	717,141
Farmland [Member] | Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Days past due	5,717	5,470
Gross loans	5,717	5,470
Farmland [Member] | Current Loans [Member] | Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable Recorded Investments Current	5,717	5,470
Consumer [Member]
Financing Receivable, Past Due [Line Items]
Days past due	53,427	59,169
Nonaccrual	669	754
Gross loans	53,427	59,169
Consumer [Member] | Non accrual loans with an allowance
Financing Receivable, Past Due [Line Items]
Nonaccrual	669	754
Consumer [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Days past due	2,195	2,298
Gross loans	2,195	2,298
Consumer [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Days past due	672	279
Gross loans	672	279
Consumer [Member] | Greater than 90 Days Past Due & Accruing [Member]
Financing Receivable, Past Due [Line Items]
Days past due	376	754
Gross loans	376	754
Consumer [Member] | Current Loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable Recorded Investments Current	$ 49,515	$ 55,084