v3.25.2
Borrowings (Details) - USD ($)
$ in Millions
6 Months Ended
Jun. 30, 2025
Dec. 31, 2024
Federal Home Loan Bank, Advances [Line Items]    
Borrowed funds $ 0.0 $ 0.0
Federal Home Loan Bank    
Federal Home Loan Bank, Advances [Line Items]    
Available and unused borrowing capacity 47.6 47.6
Banker's Bank of Wisconsin | Unsecured Line of Credit    
Federal Home Loan Bank, Advances [Line Items]    
Available and unused borrowing capacity 4.0 4.0
United Banker's Bank | Unsecured Line of Credit    
Federal Home Loan Bank, Advances [Line Items]    
Available and unused borrowing capacity $ 5.0 $ 5.0
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%