v3.26.1
Document And Entity Information - USD ($)
 12 Months Ended
Dec. 31, 2025
Feb. 28, 2026
Jun. 30, 2025
Document Information [Line Items]      
Document Type 10-K    
Document Annual Report true    
Document Period End Date Dec. 31, 2025    
Document Transition Report false    
Entity File Number 000-55756    
Entity Registrant Name Farmers and Merchants Bancshares, Inc.    
Entity Incorporation, State or Country Code MD    
Entity Tax Identification Number 81-3605835    
Entity Address, Address Line One 4510 Lower Beckleysville Road, Suite H    
Entity Address, City or Town Hampstead    
Entity Address, State or Province MD    
Entity Address, Postal Zip Code 21074    
City Area Code 410    
Local Phone Number 374-1510    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Non-accelerated Filer    
Entity Small Business true    
Entity Emerging Growth Company false    
ICFR Auditor Attestation Flag false    
Document Financial Statement Error Correction [Flag] false    
Entity Shell Company false    
Entity Public Float     $ 53,187,062
Entity Common Stock, Shares Outstanding (in shares)   3,235,707  
Auditor Firm ID 613    
Auditor Name YOUNT, HYDE & BARBOUR, P.C.    
Auditor Location Richmond, Virginia    
Entity Central Index Key 0001698022    
Current Fiscal Year End Date --12-31    
Document Fiscal Year Focus 2025    
Document Fiscal Period Focus FY    
Amendment Flag false    
Common Stock [Member]      
Document Information [Line Items]      
Title of 12(g) Security Common stock, par value $.01 per share    
Rights [Member]      
Document Information [Line Items]      
Title of 12(g) Security Common Stock Purchase Rights