v3.26.1
Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)
 3 Months Ended 6 Months Ended
Mar. 31, 2025
Mar. 01, 2025
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Apr. 30, 2021
Significant Accounting Policies [Line Items]                
Stock repurchase program, number of shares authorized to be repurchased (in shares)               375,388
Stock repurchase program, percent of stock outstanding               5.00%
Securities held to maturity, Accrued interest receivable     $ 4,700,000   $ 4,700,000   $ 2,000,000  
Shares issued for directors and employee stock plans     $ 244,000 $ 261,000 $ 499,000 $ 433,000    
Shares repurchased     35,000   85,000      
Shares repurchased, cost     $ 1,075,000   $ 2,516,000      
Repurchases of common stock         $ 2,516,000 $ 0    
Shares remaining to purchase under repurchase plan     265,272   265,272      
Number of days individually evaluation         60 days      
Fentura Financial, Inc. [Member]                
Significant Accounting Policies [Line Items]                
Shares issued for directors and employee stock plans (in shares)   6,070,836            
Cash price $ 1,800,000              
Common stock purchased   $ 57,807            
Shares issued for directors and employee stock plans   $ 193,000,000            
Directors' Stock Purchase Plan [Member]                
Significant Accounting Policies [Line Items]                
Shares issued for directors and employee stock plans (in shares)     6,103 7,005 12,081 10,306    
Shares issued for directors and employee stock plans     $ 172,000 $ 203,000 $ 348,000 $ 320,000    
Employee Stock Purchase Plan [Member]                
Significant Accounting Policies [Line Items]                
Shares issued for directors and employee stock plans (in shares)     2,505 2,397 5,788 4,611    
Shares issued for directors and employee stock plans     $ 85,000 $ 58,000 $ 178,000 $ 113,000    
FETM Shares Retired [Member]                
Significant Accounting Policies [Line Items]                
Shares issued for directors and employee stock plans (in shares)   6,750            
Shares issued for directors and employee stock plans $ 215,000