v3.26.1
Investment Securities - Additional Information (Detail)
 3 Months Ended
Mar. 31, 2026
USD ($)
Mar. 31, 2025
USD ($)
Dec. 31, 2025
USD ($)
Debt Securities, Held-to-maturity, Restricted $ 383,900,000   $ 349,200,000
Debt Securities, Available-for-sale, Restricted $ 598,400,000   624,000,000.0
Investment Securities in Unrealized Loss Position, Qualitative Disclosure, Number of Positions, Total 154    
Other Investments and Securities, at Cost $ 5,700,000   5,700,000
Federal Home Loan Bank Stock 23,200,000   32,600,000
Amortized Cost 1,129,910,000   1,096,232,000
Debt Securities, Available-for-Sale 1,042,399,000   1,014,194,000
Gain (Loss) on Equity Securities 0 $ 5,146,000  
Gain Losses Maturities And Impairment 229,000 (5,142,000)  
Residential real estate [Member] | Senior Lien      
Equity Securities Fair Value Gain Loss 5,100,000    
FCB Portfolio      
Book Value of Available-for-Sale Debt Securities Sold     53,700,000
Sales      
Gross Losses 0 5,142,000  
Gross Gains 0 0  
Gain Losses Maturities And Impairment $ 0 (5,142,000)  
US Government-sponsored Enterprises Debt Securities [Member]      
Percent of Unrealized Losses 98.00%    
Amortized Cost $ 1,000,000   1,000,000
Debt Securities, Available-for-Sale $ 991,000   $ 984,000
Corporate Debt Securities [Member]      
Investment Securities in Unrealized Loss Position, Qualitative Disclosure, Number of Positions, Total 5   7
Amortized Cost $ 42,250,000   $ 46,969,000
Debt Securities, Available-for-Sale 41,554,000   $ 46,531,000
Equity Securities [Member]      
Equity Securities without Readily Determinable Fair Value, Impairment Loss, Annual Amount $ 0 0  
Common Stock [Member]      
Equity Securities Fair Value Gain Loss   $ 5,700,000