Allowance for Credit Losses - Troubled Debt Restructurings (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) investmentSecurity	Dec. 31, 2020 USD ($) investmentSecurity	Dec. 31, 2019 USD ($) investmentSecurity
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number (in investments) | investmentSecurity	16	18	18
Pre-mod outstanding principal balance	$ 9,083	$ 6,010	$ 2,851
Post-mod outstanding principal balance	9,116	6,074	2,829
Financial impact due to TDR taken as additional provision	$ 2,521	$ 471	$ 59
Number that defaulted during the period (in investment securities) | investmentSecurity	5,000	8,000	1
Recorded investment of TDR's that defaulted during the period	$ 1,107	$ 2,862	$ 7
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions	$ (5)	$ (90)	$ 0
Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number (in investments) | investmentSecurity	8	10	2
Pre-mod outstanding principal balance	$ 6,407	$ 3,732	$ 60
Post-mod outstanding principal balance	6,401	3,827	67
Financial impact due to TDR taken as additional provision	$ 1,812	$ 381	$ 0
Number that defaulted during the period (in investment securities) | investmentSecurity	3,000	3,000	0
Recorded investment of TDR's that defaulted during the period	$ 847	$ 1,542	$ 0
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions	$ 0	$ 0	$ 0
Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number (in investments) | investmentSecurity	1	2	6
Pre-mod outstanding principal balance	$ 200	$ 172	$ 873
Post-mod outstanding principal balance	247	169	877
Financial impact due to TDR taken as additional provision	$ 0	$ 0	$ 59
Number that defaulted during the period (in investment securities) | investmentSecurity	0	5,000	0
Recorded investment of TDR's that defaulted during the period	$ 0	$ 1,320	$ 0
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions	$ 0	$ (90)	$ 0
Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number (in investments) | investmentSecurity	7	6	10
Pre-mod outstanding principal balance	$ 2,476	$ 2,106	$ 1,918
Post-mod outstanding principal balance	2,468	2,078	1,885
Financial impact due to TDR taken as additional provision	$ 709	$ 90	$ 0
Number that defaulted during the period (in investment securities) | investmentSecurity	2,000	0	1
Recorded investment of TDR's that defaulted during the period	$ 260	$ 0	$ 7
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions	$ (5)	$ 0	$ 0
Construction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number (in investments) | investmentSecurity	0	0	0
Pre-mod outstanding principal balance	$ 0	$ 0	$ 0
Post-mod outstanding principal balance	0	0	0
Financial impact due to TDR taken as additional provision	$ 0	$ 0	$ 0
Number that defaulted during the period (in investment securities) | investmentSecurity	0	0	0
Recorded investment of TDR's that defaulted during the period	$ 0	$ 0	$ 0
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions	$ 0	$ 0	$ 0
Agriculture production
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number (in investments) | investmentSecurity	0	0	0
Pre-mod outstanding principal balance	$ 0	$ 0	$ 0
Post-mod outstanding principal balance	0	0	0
Financial impact due to TDR taken as additional provision	$ 0	$ 0	$ 0
Number that defaulted during the period (in investment securities) | investmentSecurity	0	0	0
Recorded investment of TDR's that defaulted during the period	$ 0	$ 0	$ 0
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions	$ 0	$ 0	$ 0
Leases
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number (in investments) | investmentSecurity	0	0	0
Pre-mod outstanding principal balance	$ 0	$ 0	$ 0
Post-mod outstanding principal balance	0	0	0
Financial impact due to TDR taken as additional provision	$ 0	$ 0	$ 0
Number that defaulted during the period (in investment securities) | investmentSecurity	0	0	0
Recorded investment of TDR's that defaulted during the period	$ 0	$ 0	$ 0
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions	$ 0	$ 0	$ 0
CRE non-owner occupied | Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number (in investments) | investmentSecurity	5	1	0
Pre-mod outstanding principal balance	$ 4,966	$ 319	$ 0
Post-mod outstanding principal balance	4,956	314	0
Financial impact due to TDR taken as additional provision	$ 1,020	$ 314	$ 0
Number that defaulted during the period (in investment securities) | investmentSecurity	0	1,000	0
Recorded investment of TDR's that defaulted during the period	$ 0	$ 141	$ 0
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions	$ 0	$ 0	$ 0
CRE owner occupied | Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number (in investments) | investmentSecurity	1	4	2
Pre-mod outstanding principal balance	$ 740	$ 1,847	$ 60
Post-mod outstanding principal balance	742	1,877	67
Financial impact due to TDR taken as additional provision	$ 742	$ 67	$ 0
Number that defaulted during the period (in investment securities) | investmentSecurity	0	1,000	0
Recorded investment of TDR's that defaulted during the period	$ 0	$ 950	$ 0
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions	$ 0	$ 0	$ 0
Multifamily | Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number (in investments) | investmentSecurity	0	0	0
Pre-mod outstanding principal balance	$ 0	$ 0	$ 0
Post-mod outstanding principal balance	0	0	0
Financial impact due to TDR taken as additional provision	$ 0	$ 0	$ 0
Number that defaulted during the period (in investment securities) | investmentSecurity	0	0	0
Recorded investment of TDR's that defaulted during the period	$ 0	$ 0	$ 0
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions	$ 0	$ 0	$ 0
Farmland | Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number (in investments) | investmentSecurity	2	5	0
Pre-mod outstanding principal balance	$ 701	$ 1,566	$ 0
Post-mod outstanding principal balance	703	1,636	0
Financial impact due to TDR taken as additional provision	$ 50	$ 0	$ 0
Number that defaulted during the period (in investment securities) | investmentSecurity	3,000	1,000	0
Recorded investment of TDR's that defaulted during the period	$ 847	$ 451	$ 0
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions	$ 0	$ 0	$ 0
SFR 1-4 1st DT liens | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number (in investments) | investmentSecurity	0	0	3
Pre-mod outstanding principal balance	$ 0	$ 0	$ 659
Post-mod outstanding principal balance	0	0	662
Financial impact due to TDR taken as additional provision	$ 0	$ 0	$ 30
Number that defaulted during the period (in investment securities) | investmentSecurity	0	3,000	0
Recorded investment of TDR's that defaulted during the period	$ 0	$ 1,180	$ 0
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions	$ 0	$ 0	$ 0
SFR HELOCs and junior liens | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number (in investments) | investmentSecurity	1	2	3
Pre-mod outstanding principal balance	$ 200	$ 172	$ 214
Post-mod outstanding principal balance	247	169	215
Financial impact due to TDR taken as additional provision	$ 0	$ 0	$ 29
Number that defaulted during the period (in investment securities) | investmentSecurity	0	2,000	0
Recorded investment of TDR's that defaulted during the period	$ 0	$ 140	$ 0
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions	$ 0	$ (90)	$ 0
Other | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number (in investments) | investmentSecurity	0	0	0
Pre-mod outstanding principal balance	$ 0	$ 0	$ 0
Post-mod outstanding principal balance	0	0	0
Financial impact due to TDR taken as additional provision	$ 0	$ 0	$ 0
Number that defaulted during the period (in investment securities) | investmentSecurity	0	0	0
Recorded investment of TDR's that defaulted during the period	$ 0	$ 0	$ 0
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions	$ 0	$ 0	$ 0