Allowance for Credit Losses on Loans - Schedule of Non Accrual Loans (Detail) - Financial Asset Originated - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Past Due [Line Items]
Non accrual with no allowance for credit losses	$ 17,175	$ 13,909
Non accrual, no allowance including guaranteed loans	17,988	14,825
Non accrual including guaranteed loans	21,543	16,845
Total non accrual	20,730	15,855
Loans Insured or Guaranteed by US Government Authorities
Financing Receivable, Past Due [Line Items]
Non accrual with no allowance for credit losses	813	916
Total non accrual	813	990
Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Past due 90 days or more and still accruing	31	19
Commercial real estate
Financing Receivable, Past Due [Line Items]
Non accrual with no allowance for credit losses	6,786	5,316
Total non accrual	6,929	5,316
Commercial real estate | Financial Asset, Equal to or Greater than 90 Days Past Due
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	9,947	9,019
Total non accrual	12,489	9,441
Consumer | Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Past due 90 days or more and still accruing	1	19
Commercial and industrial
Financing Receivable, Past Due [Line Items]
Non accrual with no allowance for credit losses	973	476
Total non accrual	1,680	2,050
Commercial and industrial | Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Past due 90 days or more and still accruing	30	0
Construction
Financing Receivable, Past Due [Line Items]
Non accrual with no allowance for credit losses	0	0
Total non accrual	0	0
Construction | Financial Asset, Equal to or Greater than 90 Days Past Due
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	282	14
Total non accrual	445	38
Agriculture production | Financial Asset, Equal to or Greater than 90 Days Past Due
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
Total non accrual	0
Leases | Financial Asset, Equal to or Greater than 90 Days Past Due
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	677	639
Total non accrual	677	642
CRE non-owner occupied | Commercial real estate | Financial Asset, Equal to or Greater than 90 Days Past Due
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	2,266	1,411
Total non accrual	2,409	1,408
CRE owner occupied | Commercial real estate | Financial Asset, Equal to or Greater than 90 Days Past Due
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	2,024	2,024
Total non accrual	2,024	2,024
Multifamily | Commercial real estate | Financial Asset, Equal to or Greater than 90 Days Past Due
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	1,819	1,242
Total non accrual	1,819	1,242
Farmland | Commercial real estate | Financial Asset, Equal to or Greater than 90 Days Past Due
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	5,737	5,023
Total non accrual	6,719	5,192
SFR 1-4 1st DT Liens | Consumer | Financial Asset, Equal to or Greater than 90 Days Past Due
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	4,128	3,992
Total non accrual	5,665	4,217
SFR HELOCs and junior liens | Consumer | Financial Asset, Equal to or Greater than 90 Days Past Due
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	82	4
Total non accrual	105	32
Other | Consumer | Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Past due 90 days or more and still accruing	$ 1	$ 19