v3.26.1
Investment Securities - Additional Information (Detail)
3 Months Ended 6 Months Ended
Jun. 30, 2026
USD ($)
investmentSecurity
securityLoan
Jun. 30, 2025
USD ($)
Jun. 30, 2026
USD ($)
investmentSecurity
securityLoan
Jun. 30, 2025
USD ($)
Dec. 31, 2025
USD ($)
Investment Securities [Line Items]          
Proceeds from the sale of investment securities $ 1,500,000 $ 700,000 $ 4,500,000 $ 30,700,000  
Gross realized gains (losses) from the sale of investment securities   $ 4,000.0 17,000.0 $ 1,100,000  
Securities pledged as collateral 792,700,000   792,700,000   $ 839,600,000
Residential real estate mortgage-backed securities 1,200,000,000   $ 1,200,000,000    
Life of mortgage-backed securities     5 years 8 months 12 days    
Allowance for credit loss $ 0   $ 0   $ 0
Obligations of U.S. government agencies          
Investment Securities [Line Items]          
Number of available for sale securities in unrealized loss position (in investment securities) | investmentSecurity 161   161    
Percentage of aggregate depreciation in unrealized losses 10.40%   10.40%    
Obligations of states and political subdivisions          
Investment Securities [Line Items]          
Number of available for sale securities in unrealized loss position (in investment securities) | investmentSecurity 142   142    
Percentage of aggregate depreciation in unrealized losses 9.00%   9.00%    
Corporate bonds          
Investment Securities [Line Items]          
Number of available for sale securities in unrealized loss position (in investment securities) | investmentSecurity 2   2    
Percentage of aggregate depreciation in unrealized losses 1.10%   1.10%    
Asset backed securities          
Investment Securities [Line Items]          
Number of available for sale securities in unrealized loss position (in investment securities) | investmentSecurity 18   18    
Percentage of aggregate depreciation in unrealized losses 1.10%   1.10%    
Non-agency collateralized mortgage obligations          
Investment Securities [Line Items]          
Number of available for sale securities in unrealized loss position (in investment securities) | securityLoan 14   14    
Percentage of aggregate depreciation in unrealized losses 13.40%   13.40%