v3.25.4
Document And Entity Information - USD ($)
12 Months Ended
Dec. 31, 2024
Mar. 10, 2025
Jun. 30, 2024
Document Information [Line Items]      
Entity Central Index Key 0001693577    
Entity Registrant Name MainStreet Bancshares, Inc.    
Amendment Flag true    
Current Fiscal Year End Date --12-31    
Document Fiscal Period Focus FY    
Document Fiscal Year Focus 2024    
Document Type 10-K/A    
Document Annual Report true    
Document Period End Date Dec. 31, 2024    
Document Transition Report false    
Entity File Number 001-38817    
Entity Incorporation, State or Country Code VA    
Entity Tax Identification Number 81-2871064    
Entity Address, Address Line One 10089 Fairfax Boulevard    
Entity Address, City or Town Fairfax    
Entity Address, State or Province VA    
Entity Address, Postal Zip Code 22030    
City Area Code 703    
Local Phone Number 481-4567    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Accelerated Filer    
Entity Small Business true    
Entity Emerging Growth Company false    
ICFR Auditor Attestation Flag true    
Document Financial Statement Error Correction [Flag] false    
Entity Shell Company false    
Entity Public Float     $ 134,721,919
Entity Common Stock, Shares Outstanding   7,728,106  
Amendment Description EXPLANATORY NOTE   MainStreet Bancshares, Inc. ("we" or the "Company") is filing this Amendment No. 3 on Form 10-K/A (the “Amendment”)  to its Annual Report on Form 10-K for the fiscal year ended December 31, 2024, as filed with the United States Securities and Exchange Commission on March 14, 2025 (the “Original Report").  Although referenced in the opinion of the Company’s independent auditors with respect to the financial statements, the full text of the opinion of the Company’s independent auditor with respect to its internal control over financial reporting was inadvertently omitted from the Original Report. Additionally, Item 9A of the Original Report is amended to disclose the opinion of the Company’s independent auditor with respect to its internal control over financial reporting.    Pursuant to Rule 12b-15 promulgated under the Securities and Exchange Act of 1934, as amended, we have included the entire text of Part II, Item 8 and Item 9A in this Form 10-K/A. Part IV, Item 15 includes the consent of Yount, Hyde & Barbour, P.C. and updated certifications of the Company’s Chief Executive Officer and Chief Financial Officer.   Except as expressly set forth herein, this Amendment does not reflect events occurring after the date of the Original Report or modify or update any of the other disclosures contained therein in any way other than as required to reflect the amendments referred to above. Accordingly, this Amendment should be read in conjunction with the Original Report and the Company's other filings with the SEC.      
Auditor Firm ID 613    
Auditor Name Yount, Hyde & Barbour, P.C.    
Auditor Location Winchester, Virginia, USA    
Depositary Shares [Member]      
Document Information [Line Items]      
Title of 12(b) Security Depositary Shares (each representing a 1/40th  interest in a share of 7.50% Series A Fixed-Rate Non-Cumulative Perpetual Preferred Stock)    
Trading Symbol MNSBP    
Security Exchange Name NASDAQ    
Common Stock [Member]      
Document Information [Line Items]      
Title of 12(b) Security Common Stock    
Trading Symbol MNSB    
Security Exchange Name NASDAQ