v3.26.1
Description of Plan - Contributions (Details) - Bank First Retirement Plan - USD ($)
12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Description of Plan    
Automatic deferral rate 6.00%  
Automatic yearly increases of deferral rate 1.00%  
Maximum deferral rate 15.00%  
Discretionary match 60.00% 60.00%
Participants' eligible compensation for matching contribution 6.00% 6.00%
Matching contributions $ 1,505,060 $ 1,414,061
Profit-sharing contribution $ 0 $ 0