v3.26.3
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk (Details)
9 Months Ended 12 Months Ended
Sep. 30, 2026
USD ($)
item
Dec. 31, 2025
USD ($)
item
Sep. 30, 2025
USD ($)
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk      
Amount to be reclassified as an increase to interest expense during the next twelve months $ 483,000    
Two financial institutions      
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk      
Cash collateral pledged with financial institutions, dollars 0 $ 660,000  
Number of financial institutions in which cash collateral pledged   1  
Interest Rate Swap      
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk      
Cash collateral pledged with financial institutions, dollars $ 6,700,000 $ 3,500,000  
Number of financial institutions in which cash collateral pledged 2 1  
Carrying amount of securities secured $ 0   $ 0
Designated as Hedging Instrument      
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk      
Derivative assets designated as hedging instruments, fair value 4,977,000 $ 3,155,000  
Designated as Hedging Instrument | Interest Rate Products | Cash flow hedge of junior subordinated debentures and was executed to pay fixed and receive variable rate cash flows      
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk      
Notional amount 25,800,000 25,800,000  
Designated as Hedging Instrument | Interest Rate Products | OSBC Affiliates      
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk      
Notional amount $ 25,774,000 $ 25,774,000  
Derivative, number of transactions | item 1 1  
Derivative assets designated as hedging instruments, fair value $ 4,977,000 $ 3,155,000  
Designated as Hedging Instrument | Interest Rate Swap | Cash flow hedges of certain variable rate commercial and commercial real estate loan pools      
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk      
Notional amount 0 0  
Not Designated as Hedging Instrument      
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk      
Derivative assets designated as hedging instruments, fair value 2,032,000 1,197,000  
Derivative liabilities designated as hedging instruments, fair value 2,047,000 1,157,000  
Not Designated as Hedging Instrument | Interest Rate Products | Commercial Loan Customers      
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk      
Notional amount $ 90,280,000 $ 125,808,000  
Derivative, number of transactions | item 10 12  
Derivative assets designated as hedging instruments, fair value $ 2,025,000 $ 1,143,000  
Derivative liabilities designated as hedging instruments, fair value 2,025,000 1,143,000  
Not Designated as Hedging Instrument | Interest Rate Swap      
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk      
Notional amount 90,300,000 125,800,000  
Not Designated as Hedging Instrument | Commitments.      
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk      
Notional amount 13,600,000 14,800,000  
Not Designated as Hedging Instrument | Interest Rate Lock Commitments and Forward Contracts.      
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk      
Notional amount $ 13,624,000 $ 14,790,000  
Derivative, number of transactions | item 36 40  
Derivative assets designated as hedging instruments, fair value   $ 31,000  
Derivative liabilities designated as hedging instruments, fair value $ 20,000    
Not Designated as Hedging Instrument | Other Contracts      
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk      
Notional amount $ 46,996,000 $ 63,080,000  
Derivative, number of transactions | item 4 5  
Derivative assets designated as hedging instruments, fair value $ 7,000 $ 23,000  
Derivative liabilities designated as hedging instruments, fair value $ 2,000 $ 14,000