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Summary of Significant Accounting Policies - Additional Information (Detail)
 12 Months Ended
Mar. 27, 2020
Dec. 31, 2021
USD ($)
Portfolio
Branch
Property
Dec. 31, 2020
USD ($)
Summary Of Significant Accounting Policies [Line Items]      
Number of branches | Branch   206  
Number of ATM | Property   203  
Wholly-owned trust subsidiaries | Property   11  
Held for sale securities, percentage of purchase price as condition for sale   15.00%  
Allowance for credit losses, held-to-maturity debt securities   $ 268,000 $ 326,000
Non-accrual status period   90 days  
Loans returned to accrual status, performance period   6 months  
Consumer loan TDR extended maturity period   6 months  
Number of categories of loan portfolio | Portfolio   3  
Indefinite - lived intangible assets   $ 0  
Period of interest rate lock commitments   60 days  
ASU 2019-12 Income Taxes (Topic 740)      
Summary Of Significant Accounting Policies [Line Items]      
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]   true  
Change in Accounting Principle, Accounting Standards Update, Adoption Date   Jan. 01, 2021  
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]   true  
Accounting Standard Update Extensible List   ASU 2019-12  
Land Improvements [Member]      
Summary Of Significant Accounting Policies [Line Items]      
Property, plant and equipment, Useful life   15 years  
Commercial [Member] | Hospitality Sector [Member]      
Summary Of Significant Accounting Policies [Line Items]      
Description of extension period for loan principal and interest payments under the plan   If a loan were to meet the criteria, they would be eligible to have twelve months of interest payments deferred or three months of principal and interest payments plus nine months of interest-only payments. There are predetermined contractual re-evaluation triggers reviewed throughout the deferred period to determine if a borrower should return to a normal amortization schedule prior to the completion of the twelve month period.  
CARES Act, Paycheck Protection Program [Member]      
Summary Of Significant Accounting Policies [Line Items]      
Loans receivable, Interest rate 1.00%    
Mortgage-Backed Securities and Collateralized Mortgage Obligations of Government Sponsored Entities and Agencies [Member]      
Summary Of Significant Accounting Policies [Line Items]      
Allowance for credit losses, held-to-maturity debt securities   $ 0  
Consumer Loan [Member]      
Summary Of Significant Accounting Policies [Line Items]      
Period of closed end loans loans charged down to net realizable value   120 days  
Home Equity [Member]      
Summary Of Significant Accounting Policies [Line Items]      
Period of closed end loans loans charged down to net realizable value   180 days  
Residential Real Estate Loans [Member]      
Summary Of Significant Accounting Policies [Line Items]      
Period of closed end loans loans charged down to net realizable value   180 days  
Minimum [Member]      
Summary Of Significant Accounting Policies [Line Items]      
Percentage of voting interest     50.00%
Forecast period to measure expected credit losses on loan portfolio   1 year  
Model reversion period to measure expected credit losses on loan portfolio   1 year  
Weighted-average estimated useful lives   10 years  
Non-compete agreements, amortization period   1 year  
Minimum [Member] | Furniture and Equipment [Member]      
Summary Of Significant Accounting Policies [Line Items]      
Property, plant and equipment, Useful life   3 years  
Minimum [Member] | Building and Building Improvements [Member]      
Summary Of Significant Accounting Policies [Line Items]      
Property, plant and equipment, Useful life   15 years  
Maximum [Member]      
Summary Of Significant Accounting Policies [Line Items]      
Forecast period to measure expected credit losses on loan portfolio   2 years  
Model reversion period to measure expected credit losses on loan portfolio   3 years  
Weighted-average estimated useful lives   16 years  
Non-compete agreements, amortization period   4 years  
Maximum [Member] | Furniture and Equipment [Member]      
Summary Of Significant Accounting Policies [Line Items]      
Property, plant and equipment, Useful life   10 years  
Maximum [Member] | Building and Building Improvements [Member]      
Summary Of Significant Accounting Policies [Line Items]      
Property, plant and equipment, Useful life   39 years  
Maximum [Member] | CARES Act, Paycheck Protection Program [Member]      
Summary Of Significant Accounting Policies [Line Items]      
Extension period for loan principal and interest payments   180 days  
Loans receivable, threshold period past due   30 days