Quarterly report pursuant to Section 13 or 15(d)

Note 1 - Summary of Significant Accounting Policies (Details Textual)

v3.24.1.u1
Note 1 - Summary of Significant Accounting Policies (Details Textual)
 3 Months Ended
Apr. 15, 2024
USD ($)
$ / shares
shares
Mar. 31, 2024
USD ($)
Dec. 31, 2023
USD ($)
Mar. 31, 2023
USD ($)
Jan. 01, 2023
USD ($)
Dec. 31, 2022
USD ($)
Number Of Full Service Branch Offices   26        
Financing Receivable, Allowance for Credit Loss   $ 17,440,000 $ 17,442,000 $ 16,794,000   $ 15,285,000
Retained Earnings (Accumulated Deficit)   96,471,000 89,760,000      
Deferred Income Tax Assets, Net   7,385,000 7,202,000      
Interest Receivable   10,266,000 8,976,000      
Increase (Decrease) in Loan, Held-for-Sale   0        
Collateralized Mortgage-Backed Securities [Member]            
Credit Risk Derivatives, at Fair Value, Net   $ 1,000,000 (17,000,000)      
Interest Rate Swap [Member]            
Derivative, Number of Instruments Held   2        
Derivative Asset, Notional Amount   $ 105,700,000 108,200,000      
Derivative Asset, Subject to Master Netting Arrangement, before Offset   5,600,000 4,900,000      
Derivative Asset, Subject to Master Netting Arrangement, Liability Offset   5,600,000 4,900,000      
Loans and Finance Receivables [Member]            
Interest Receivable   4,800,000 5,300,000      
Debt Securities [Member]            
Interest Receivable   4,400,000 3,400,000      
Interest Rate Lock Commitments [Member]            
Credit Risk Derivatives, at Fair Value, Net   (2,000,000) $ 1,000,000      
Cumulative Effect, Period of Adoption, Adjustment [Member]            
Financing Receivable, Allowance for Credit Loss           $ 1,476,000
Accounting Standards Update 2016-13 [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]            
Financing Receivable, Allowance for Credit Loss         $ 1,500,000  
Off-Balance-Sheet, Credit Loss, Liability         62,000  
Retained Earnings (Accumulated Deficit)         1,200,000  
Deferred Income Tax Assets, Net         $ 323,000  
Minimum [Member]            
Peer Group Assets   1,000,000,000        
Maximum [Member]            
Peer Group Assets   $ 3,000,000,000        
Wintrust Financial Corporation [Member] | Subsequent Event [Member]            
Business Combination, Consideration Transferred $ 510,300,000          
Business Acquisition, Share Price (in dollars per share) | $ / shares $ 14.85          
Business Acquisition, Exchange Ratio, Collar (in dollars per share) | $ / shares 12          
Business Acquisition, Exchange Ratio, Reference Price (in dollars per share) | $ / shares $ 101.03          
Wintrust Financial Corporation [Member] | Subsequent Event [Member] | Exchange Scenario 2 [Member]            
Business Acquisition, Exchange Ratio, Shares Received Per Shares Owned (in shares) | shares 0.1668          
Wintrust Financial Corporation [Member] | Subsequent Event [Member] | Exchange Scenario 3 [Member]            
Business Acquisition, Exchange Ratio, Shares Received Per Shares Owned (in shares) | shares 0.1314          
Wintrust Financial Corporation [Member] | Subsequent Event [Member] | Minimum [Member] | Exchange Scenario 1 [Member]            
Business Acquisition, Exchange Ratio, Closing Price (in dollars per share) | $ / shares $ 89.03          
Business Acquisition, Exchange Ratio, Shares Received Per Shares Owned (in shares) | shares 0.1314          
Wintrust Financial Corporation [Member] | Subsequent Event [Member] | Minimum [Member] | Exchange Scenario 3 [Member]            
Business Acquisition, Exchange Ratio, Closing Price (in dollars per share) | $ / shares $ 113.03          
Wintrust Financial Corporation [Member] | Subsequent Event [Member] | Maximum [Member] | Exchange Scenario 1 [Member]            
Business Acquisition, Exchange Ratio, Closing Price (in dollars per share) | $ / shares $ 113.03          
Business Acquisition, Exchange Ratio, Shares Received Per Shares Owned (in shares) | shares 0.1668          
Wintrust Financial Corporation [Member] | Subsequent Event [Member] | Maximum [Member] | Exchange Scenario 2 [Member]            
Business Acquisition, Exchange Ratio, Closing Price (in dollars per share) | $ / shares $ 89.03