v3.26.1
Note 1 - Significant Accounting Policies (Details Textual)
$ in Thousands
 3 Months Ended 6 Months Ended
Dec. 31, 2025
USD ($)
Jun. 30, 2026
USD ($)
shares
Jun. 30, 2025
USD ($)
shares
Jun. 30, 2026
USD ($)
shares
Jun. 30, 2025
USD ($)
shares
Number of Unconsolidated Business Trusts Formed to Issue Trust Preferred Securities   5   5  
Debt Securities, Available-for-Sale, Allowance for Credit Loss $ 0 $ 0   $ 0  
Financing Receivable, Unamortized Loan Cost (Fee) 1,300 1,100   1,100  
Investment Income, Net, Amortization of Discount and Premium       $ 300  
Interest Income on Commercial and Mortgage Loans Discontinued Period (Day)       90 days  
Maximum Delinquency Period for Consumer and Credit Card Loans to be Charged Off (Day)       120 days  
Loan, Mortgage, Held-for-Sale, Fair Value Disclosure 17,300 31,800   $ 31,800  
Financing Receivable, Credit Loss, Expense (Reversal)   (1,800) $ 1,600 (3,600) $ 3,700
Financing Receivable, Accrued Interest, after Allowance for Credit Loss 17,500 17,400   17,400  
Continuing Involvement with Transferred Financial Assets, Principal Amount Outstanding 1,690,000 1,710,000   1,710,000  
Servicing Asset at Amortized Cost 13,600 13,700   13,700  
Servicing Asset at Fair Value, Amount 21,400 $ 23,400   $ 23,400  
Restricted Stock [Member]          
Incremental Common Shares Attributable to Participating Nonvested Shares with Non-forfeitable Dividend Rights (in shares) | shares   256,000 277,000 256,000 277,000
Eastern Michigan Financial Corp. [Member]          
Business Combination, Recognized Asset Acquired, Asset Including Goodwill $ 572,000        
Business Combination Branches Acquired 11        
Business Combination, Recognized Asset Acquired, Financing Receivable, Unamortized Purchase Premium (Discount) $ (1,500)        
Goodwill, Acquired During Period $ 24,200