Allowance for Credit Losses - Schedule of Non Accrual Loans (Detail) - Financial Asset Originated - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Financing Receivable, Past Due [Line Items]
Non accrual with no allowance for credit losses	$ 26,138	$ 21,703
Non accrual with no allowance for credit losses	26,817	22,390
Nonaccrual loans	28,790	26,864
Total non accrual	28,015	26,053
Loans Insured or Guaranteed by US Government Authorities
Financing Receivable, Past Due [Line Items]
Non accrual with no allowance for credit losses	679	687
Total non accrual	775	811
> 90 days
Financing Receivable, Past Due [Line Items]
Past due 90 days or more and still accruing	0	0
Commercial real estate
Financing Receivable, Past Due [Line Items]
Non accrual with no allowance for credit losses	18,298	7,689
Total non accrual	18,297	8,709
Commercial real estate | > 90 days
Financing Receivable, Past Due [Line Items]
Past due 90 days or more and still accruing	0	0
Consumer
Financing Receivable, Past Due [Line Items]
Non accrual with no allowance for credit losses	7,165	9,498
Total non accrual	7,951	11,408
Consumer | > 90 days
Financing Receivable, Past Due [Line Items]
Past due 90 days or more and still accruing	0	0
Commercial and industrial
Financing Receivable, Past Due [Line Items]
Non accrual with no allowance for credit losses	1,339	652
Total non accrual	2,407	2,183
Commercial and industrial | > 90 days
Financing Receivable, Past Due [Line Items]
Past due 90 days or more and still accruing	0	0
Construction
Financing Receivable, Past Due [Line Items]
Non accrual with no allowance for credit losses	15	4,546
Total non accrual	15	4,546
Construction | > 90 days
Financing Receivable, Past Due [Line Items]
Past due 90 days or more and still accruing	0	0
Agriculture production
Financing Receivable, Past Due [Line Items]
Non accrual with no allowance for credit losses	0	5
Total non accrual	120	18
Agriculture production | > 90 days
Financing Receivable, Past Due [Line Items]
Past due 90 days or more and still accruing	0	0
Leases
Financing Receivable, Past Due [Line Items]
Non accrual with no allowance for credit losses	0	0
Total non accrual	0	0
Leases | > 90 days
Financing Receivable, Past Due [Line Items]
Past due 90 days or more and still accruing	0	0
CRE non-owner occupied | Commercial real estate
Financing Receivable, Past Due [Line Items]
Non accrual with no allowance for credit losses	12,591	3,110
Total non accrual	7,713	3,110
CRE non-owner occupied | Commercial real estate | > 90 days
Financing Receivable, Past Due [Line Items]
Past due 90 days or more and still accruing	0	0
CRE owner occupied | Commercial real estate
Financing Receivable, Past Due [Line Items]
Non accrual with no allowance for credit losses	0	3,111
Total non accrual	4,877	4,061
CRE owner occupied | Commercial real estate | > 90 days
Financing Receivable, Past Due [Line Items]
Past due 90 days or more and still accruing	0	0
Multifamily | Commercial real estate
Financing Receivable, Past Due [Line Items]
Non accrual with no allowance for credit losses	4,560	0
Total non accrual	4,560	0
Multifamily | Commercial real estate | > 90 days
Financing Receivable, Past Due [Line Items]
Past due 90 days or more and still accruing	0	0
Farmland | Commercial real estate
Financing Receivable, Past Due [Line Items]
Non accrual with no allowance for credit losses	1,147	1,468
Total non accrual	1,147	1,538
Farmland | Commercial real estate | > 90 days
Financing Receivable, Past Due [Line Items]
Past due 90 days or more and still accruing	0	0
SFR 1-4 1st DT liens | Consumer
Financing Receivable, Past Due [Line Items]
Non accrual with no allowance for credit losses	3,831	4,950
Total non accrual	3,833	5,093
SFR 1-4 1st DT liens | Consumer | > 90 days
Financing Receivable, Past Due [Line Items]
Past due 90 days or more and still accruing	0	0
SFR HELOCs and junior liens | Consumer
Financing Receivable, Past Due [Line Items]
Non accrual with no allowance for credit losses	3,282	4,480
Total non accrual	4,034	6,148
SFR HELOCs and junior liens | Consumer | > 90 days
Financing Receivable, Past Due [Line Items]
Past due 90 days or more and still accruing	0	0
Other | Consumer
Financing Receivable, Past Due [Line Items]
Non accrual with no allowance for credit losses	52	68
Total non accrual	84	167
Other | Consumer | > 90 days
Financing Receivable, Past Due [Line Items]
Past due 90 days or more and still accruing	$ 0	$ 0