v3.26.1
Short and Long-Term Borrowings - Schedule of Junior Subordinated Debentures and Subordinated Notes (Details) - USD ($)
6 Months Ended
Jun. 30, 2026
Dec. 31, 2025
Jul. 31, 2021
Debt Instrument [Line Items]      
Carrying Value $ 92,750,000 $ 134,860,000  
Junior subordinated debentures      
Debt Instrument [Line Items]      
Par 0    
Unamortized premium /(discount) / debt issue costs 0    
Carrying Value $ 0 $ 42,215,000  
Junior subordinated debentures | 2005 Mid-Wisconsin Financial Services, Inc.      
Debt Instrument [Line Items]      
Interest Rate 0.00% 5.41%  
Par $ 0    
Unamortized premium /(discount) / debt issue costs 0    
Carrying Value $ 0 $ 8,333,000  
Floating interest rate basis spread 1.43%    
Junior subordinated debentures | 2006 Baylake Corp.      
Debt Instrument [Line Items]      
Interest Rate 0.00% 5.30%  
Par $ 0    
Unamortized premium /(discount) / debt issue costs 0    
Carrying Value $ 0 $ 14,133,000  
Floating interest rate basis spread 1.35%    
Junior subordinated debentures | 2004 First Menasha Bancshares, Inc.      
Debt Instrument [Line Items]      
Interest Rate 0.00% 6.76%  
Par $ 0    
Unamortized premium /(discount) / debt issue costs 0    
Carrying Value $ 0 $ 4,799,000  
Floating interest rate basis spread 2.79%    
Junior subordinated debentures | County Bancorp Statutory Trust II      
Debt Instrument [Line Items]      
Interest Rate 0.00% 5.51%  
Par $ 0    
Unamortized premium /(discount) / debt issue costs 0    
Carrying Value $ 0 $ 5,741,000  
Floating interest rate basis spread 1.53%    
Junior subordinated debentures | County Bancorp Statutory Trust III      
Debt Instrument [Line Items]      
Interest Rate 0.00% 5.67%  
Par $ 0    
Unamortized premium /(discount) / debt issue costs 0    
Carrying Value $ 0 $ 5,683,000  
Floating interest rate basis spread 1.69%    
Junior subordinated debentures | Fox River Valley Capital Trust      
Debt Instrument [Line Items]      
Interest Rate 0.00% 7.89%  
Par $ 0    
Unamortized premium /(discount) / debt issue costs 0    
Carrying Value $ 0 $ 3,526,000  
Floating interest rate basis spread 3.40%    
Junior subordinated debentures | ATBancorp Statutory Trust I      
Debt Instrument [Line Items]      
Interest Rate 0.00% 0.00%  
Par $ 0    
Unamortized premium /(discount) / debt issue costs 0    
Carrying Value $ 0 $ 0  
Floating interest rate basis spread 1.68%    
Junior subordinated debentures | ATBancorp Statutory Trust II      
Debt Instrument [Line Items]      
Interest Rate 0.00% 0.00%  
Par $ 0    
Unamortized premium /(discount) / debt issue costs 0    
Carrying Value $ 0 $ 0  
Floating interest rate basis spread 1.65%    
Junior subordinated debentures | Barron Ivestment Capital Trust I      
Debt Instrument [Line Items]      
Interest Rate 0.00% 0.00%  
Par $ 0    
Unamortized premium /(discount) / debt issue costs 0    
Carrying Value $ 0 $ 0  
Floating interest rate basis spread 2.15%    
Junior subordinated debentures | Central Bancshares Capital Trust II      
Debt Instrument [Line Items]      
Interest Rate 0.00% 0.00%  
Par $ 0    
Unamortized premium /(discount) / debt issue costs 0    
Carrying Value $ 0 $ 0  
Floating interest rate basis spread 3.50%    
Junior subordinated debentures | MidWestOne Statutory Trust II      
Debt Instrument [Line Items]      
Interest Rate 0.00% 0.00%  
Par $ 0    
Unamortized premium /(discount) / debt issue costs 0    
Carrying Value $ 0 $ 0  
Floating interest rate basis spread 1.59%    
Subordinated notes      
Debt Instrument [Line Items]      
Carrying Value $ 92,750,000 $ 92,645,000  
Subordinated notes | Subordinated Notes due 2031      
Debt Instrument [Line Items]      
Interest Rate 3.13% 3.13%  
Par $ 92,750,000   $ 100,000,000
Unamortized premium /(discount) / debt issue costs 0    
Carrying Value $ 92,750,000 $ 92,645,000