Quarterly report [Sections 13 or 15(d)]

Derivatives and Hedging Activities - Schedule of Fair Value of Derivative Financial Instruments as well as their Classification on Consolidated Balance Sheets (Detail)

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Derivatives and Hedging Activities - Schedule of Fair Value of Derivative Financial Instruments as well as their Classification on Consolidated Balance Sheets (Detail) - USD ($)
Sep. 30, 2026
Dec. 31, 2025
Derivatives Fair Value [Line Items]    
Total derivative assets $ 4,397,000 $ 2,719,000
Not Designated as Hedging Instrument    
Derivatives Fair Value [Line Items]    
Total derivative assets 3,164,000 2,579,000
Total derivative liabilities 3,138,000 2,568,000
Not Designated as Hedging Instrument | Back-to-Back Interest Rate Swaps Related to Customer Loans    
Derivatives Fair Value [Line Items]    
Notional Amount 59,099,000 61,350,000
Total derivative assets 3,164,000 2,579,000
Total derivative liabilities 3,138,000 2,568,000
Designated as Hedging Instrument    
Derivatives Fair Value [Line Items]    
Total derivative assets 1,233,000 140,000
Designated as Hedging Instrument | Pay-Fixed Interest Rate Swap Related to State of California Time Deposits    
Derivatives Fair Value [Line Items]    
Notional Amount 180,000,000  
Total derivative assets 853,000  
Designated as Hedging Instrument | Interest Rate Cap Related to Trust Preferred Securities    
Derivatives Fair Value [Line Items]    
Notional Amount 26,000,000  
Total derivative assets $ 380,000  
Designated as Hedging Instrument | Pay-Fixed Interest Rate Swaps Related to Customer Loans    
Derivatives Fair Value [Line Items]    
Notional Amount   175,000,000
Total derivative assets   $ 140,000