XML 39 R33.htm IDEA: XBRL DOCUMENT v3.25.3
Summary of Significant Accounting Policies - Additional Information (Details)
 3 Months Ended 9 Months Ended
Mar. 31, 2025
USD ($)
Mar. 01, 2025
USD ($)
shares
Sep. 30, 2025
USD ($)
shares
Sep. 30, 2024
USD ($)
Sep. 30, 2025
USD ($)
Segment
shares
Sep. 30, 2024
USD ($)
Dec. 31, 2024
USD ($)
Apr. 30, 2021
shares
Significant Accounting Policies [Line Items]                
Stock repurchase program, number of shares authorized to be repurchased (in shares) | shares               375,388
Stock repurchase program, percent of stock outstanding               5.00%
Securities held to maturity, Accrued interest receivable     $ 2,300,000   $ 2,300,000   $ 2,000,000  
Shares issued for directors and employee stock plans     $ 245,000 $ 165,000 $ 678,000 $ 280,000    
Number of days individually evaluation         60 days      
Stock repurchased during period, shares (in shares) | shares         0      
Number of reportable segments | Segment         1      
ASU 2023-07                
Significant Accounting Policies [Line Items]                
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]     true   true      
Change in Accounting Principle, Accounting Standards Update, Adoption Date     Dec. 31, 2024   Dec. 31, 2024      
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]     true   true      
Fentura Financial, Inc. [Member]                
Significant Accounting Policies [Line Items]                
Shares issued for directors and employee stock plans (in shares) | shares   6,070,836            
Cash price $ 1,800,000              
Common stock purchased   $ 57,807            
Shares issued for directors and employee stock plans   $ 192,800,000            
Directors' Stock Purchase Plan [Member]                
Significant Accounting Policies [Line Items]                
Shares issued for directors and employee stock plans (in shares) | shares     6,136   16,442      
Shares issued for directors and employee stock plans     $ 176,000   $ 496,000      
Employee Stock Purchase Plan [Member]                
Significant Accounting Policies [Line Items]                
Shares issued for directors and employee stock plans (in shares) | shares     2,802   7,413      
Shares issued for directors and employee stock plans     $ 69,000   $ 182,000      
FETM Shares Retired [Member]                
Significant Accounting Policies [Line Items]                
Shares issued for directors and employee stock plans (in shares) | shares   6,750            
Shares issued for directors and employee stock plans $ 215,000