v3.26.1
Borrowings (Details) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2026
Dec. 31, 2025
Federal Home Loan Bank, Advances [Line Items]    
Borrowed funds $ 0 $ 0
Federal Home Loan Bank    
Federal Home Loan Bank, Advances [Line Items]    
Available and unused borrowing capacity 51,100 50,400
Banker's Bank of Wisconsin | Unsecured Line of Credit    
Federal Home Loan Bank, Advances [Line Items]    
Available and unused borrowing capacity 4,000 4,000
United Banker's Bank | Unsecured Line of Credit    
Federal Home Loan Bank, Advances [Line Items]    
Available and unused borrowing capacity $ 5,000 $ 5,000
Minimum | Federal Home Loan Bank    
Federal Home Loan Bank, Advances [Line Items]    
Book value of the Bank's qualifying loans based on the pledged loan class (as a percent) 60.00%  
Investment securities pledged (as a percent) 90.00%  
Maximum | Federal Home Loan Bank    
Federal Home Loan Bank, Advances [Line Items]    
Book value of the Bank's qualifying loans based on the pledged loan class (as a percent) 80.00%  
Investment securities pledged (as a percent) 98.00%